WorldWideScience

Sample records for subcooled liquid nitrogen

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

    International Nuclear Information System (INIS)

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

    2011-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Y.F. [Chinese Academy of Sciences, Beijing (China). Technical Institute of Physics and Chemistry; Graduate School of Chinese Academy of Sciences, Beijing (China); Gong, L.H.; Xu, X.D.; Li, L.F.; Zhang, L. [Chinese Academy of Sciences, Beijing (China). Technical Institute of Physics and Chemistry; Xiao, L.Y. [Chinese Academy of Sciences, Beijing (China). Institute of Electrical Engineering

    2005-04-01

    A 10 m long, three-phase AC high-temperature superconducting (HTS) power cable had been fabricated and tested in China August 2003. The sub-cooled liquid nitrogen (LN{sub 2}) was used to cool the HTS cable. The sub-cooled LN{sub 2} circulation was built by means of a centrifugal pump through a heat exchanger in the sub-cooler, the three-phase HTS cable cryostats and a LN{sub 2} gas-liquid separator. The LN{sub 2} was cooled down to 65 K by means of decompressing, and the maximum cooling capacity was about 3.3 kW and the amount of consumed LN{sub 2} was about 72 L/h at 1500 A. Cryogenic system design, test and some experimental results would be presented in this paper. (author)

  3. Critical Current Properties of HTS Twisted Stacked-Tape Cable in Subcooled- and Pressurized-Liquid Nitrogen

    International Nuclear Information System (INIS)

    Tomita, M; Suzuki, K; Fukumoto, Y; Ishihara, A; Akasaka, T; Kobayashi, Y; Maeda, A; Takayasu, M

    2015-01-01

    A 2 m length Twisted Stacked-Tape Cable (TSTC) conductor which was fabricated by 32-YBCO-tapes (4 mm width) with a 200 mm twist pitch was investigated at various temperatures near 77 K in subcooled- and pressurized-liquid nitrogen. The critical current of the TSTC cable which was 1.45 kA at 77 K measured from 64 K to 85 K by controlling the equilibrium vapor pressure of nitrogen bath and were varied from 3.65 kA at 64 K to 0.42 kA at 85 K. The temperature dependence of cables’ critical current agrees with that of the 4 mm width YBCO tape. These results are encouraging for applications of a compact Twisted Stacked-Tape Cable application in railway systems. (paper)

  4. Effects of Parallel Channel Interactions, Steam Flow, Liquid Subcool ...

    African Journals Online (AJOL)

    Tests were performed to examine the effects of parallel channel interactions, steam flow, liquid subcool and channel heat addition on the delivery of liquid from the upper plenum into the channels and lower plenum of Boiling Water Nuclear Power Reactors during reflood transients. Early liquid delivery into the channels, ...

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

    Science.gov (United States)

    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 μm 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. Vapour phase motion in cryogenic systems containing superheated and subcooled liquids

    Science.gov (United States)

    Kirichenko, Yu. A.; Chernyakov, P. S.; Seregin, V. E.

    The development of vent pipelines, and venting storage tanks for cryogenic liquids requires the knowledge of the law of motion as well as regularities of vapour content variation in the liquid and heat dissipation by the vapour phase. This is a theoretical study of the effect of superheating (subcooling) of the liquid, relative acceleration and reduced pressure upon the size and velocity of noninteracting vapour bubbles, moving in the liquid, and upon their resistance and heat transfer coefficients.

  7. Thermodynamic study of the injection of steam bubbles in a subcooled liquid

    International Nuclear Information System (INIS)

    Besset, Jacqueline.

    1980-10-01

    The behaviour of steam bubbles injected in a subcooled liquid has been studied. Water was the fluid chosen for this experiment for the steam and the liquid. The experiment was carried out at atmospheric pressure and the variable parameters were the ΔT subcooling (difference between the saturation temperature at the pressure under consideration and that of the liquid around the bubbles) and the steam output. We first studied the formation of the bubbles in a wide subcooling range (7 0 C 0 C). In this study a straight correlation was obtained giving the volume of the bubbles formed at the injector outlet, which is valid for a wide range of variables. The implosion of free bubbles in the liquid after they separated from the injector was then studied. In these experiments the significant implosion parameters are the Jakob Ja number, that measures the possibility of the liquid to absorb the heat given off by the condensation, and the Peclet Pe(RO) number, that defines the relative participation of conduction and convection in the heat exchanges. These numbers vary in the areas: 35 [fr

  8. Effect of liquid subcooling on acoustic characteristics during the condensation process of vapor bubbles in a subcooled pool

    International Nuclear Information System (INIS)

    Tang, Jiguo; Yan, Changqi; Sun, Licheng; Li, Ya; Wang, Kaiyuan

    2015-01-01

    Highlights: • Deviations of signals increase first and then decrease with increase in subcooling. • Two typical waveforms are observed and correspond to bubble split-up and collapse. • Dominant frequency in low frequency region is found for all condensation regimes. • Peaks in high frequency region were only found in capillary wave regime. • Bubble collapse frequency is close to frequency of first peak in amplitude spectra. - Abstract: Sound characteristics of direct contact condensation of vapor bubbles in a subcooled pool were investigated experimentally with a hydrophone and a high-speed video camera. Three different condensation modes were observed, which were referred to as shape oscillation regime, transition regime and capillary wave regime in the paper. Time domain analysis indicated that the acoustic signals were boosted in their maximum amplitude with increase in subcooling, while their standard and average absolute deviations shifted to decrease after reaching a peak value. In addition, two different waveforms were found, possible sources of which were split-up and collapse of bubbles, respectively. From the amplitude spectra obtained by FFT, the first dominant frequency was found at frequency of 150–300 Hz for all condensation regimes, whereas some peaks in high frequency region were observed only for the capillary wave regime. The first dominant frequency was the result of the periodic variation in the vapor bubble volume, and the peaks in high frequency region were due to the high-frequency oscillation of water in pressure caused by sudden bubble collapse. The frequency of first peak was considered to be resulted from the periodic bubble collapse or split-up and thus was close to the bubble collapse frequency obtained from snapshots of bubble condensation. Moreover, according to results of short-time Fourier transform (STFT), the time intervals in which a certain process of bubble condensing occurred could be well known.

  9. Demonstrating Paramagnetism Using Liquid Nitrogen.

    Science.gov (United States)

    Simmonds, Ray; And Others

    1994-01-01

    Describes how liquid nitrogen is attracted to the poles of neodymium magnets. Nitrogen is not paramagnetic, so the attraction suggests that the liquid nitrogen contains a small amount of oxygen, which causes the paramagnetism. (MVL)

  10. Replaceable liquid nitrogen piping

    International Nuclear Information System (INIS)

    Yasujima, Yasuo; Sato, Kiyoshi; Sato, Masataka; Hongo, Toshio

    1982-01-01

    This liquid nitrogen piping with total length of about 50 m was made and installed to supply the liquid nitrogen for heat insulating shield to three superconducting magnets for deflection and large super-conducting magnet for detection in the π-meson beam line used for high energy physics experiment in the National Laboratory for High Energy Physics. The points considered in the design and manufacture stages are reported. In order to minimize the consumption of liquid nitrogen during transport, vacuum heat insulation method was adopted. The construction period and cost were reduced by the standardization of the components, the improvement of welding works and the elimination of ineffective works. For simplifying the maintenance, spare parts are always prepared. The construction and the procedure of assembling of the liquid nitrogen piping are described. The piping is of double-walled construction, and its low temperature part was made of SUS 316L. The super-insulation by aluminum vacuum evaporation and active carbon were attached on the external surface of the internal pipe. The final leak test and the heating degassing were performed. The tests on evacuation, transport capacity and heat entry are reported. By making the internal pipe into smaller size, the piping may be more efficient. (Kako, I.)

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

    Science.gov (United States)

    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.

  12. Thermodynamic analysis of a novel energy-efficient refrigeration system subcooled by liquid desiccant dehumidification and evaporation

    International Nuclear Information System (INIS)

    She, Xiaohui; Yin, Yonggao; Zhang, Xiaosong

    2014-01-01

    Highlights: • An energy-efficient refrigeration system with a novel subcooling method is proposed. • Thermodynamic analysis is conducted to discuss the effects of operation parameters. • Two different utilization ways of condensation heat are compared. • The system achieves much higher COP, even higher than reverse Carnot cycle. • Suggested mass concentration for LiCl–H 2 O is around 32% at a typical case. - Abstract: A new energy-efficient refrigeration system subcooled by liquid desiccant dehumidification and evaporation was proposed in this paper. In the system, liquid desiccant system could produce very dry air for an indirect evaporative cooler, which would subcool the vapor compression refrigeration system to get higher COP than conventional refrigeration system. The desiccant cooling system can use the condensation heat for the desiccant regeneration. Thermodynamic analysis is made to discuss the effects of operation parameters (condensing temperature, liquid desiccant concentration, ambient air temperature and relative humidity) on the system performance. Results show that the proposed hybrid vapor compression refrigeration system achieves significantly higher COP than conventional vapor compression refrigeration system, and even higher than the reverse Carnot cycle at the same operation conditions. The maximum COPs of the hybrid systems using hot air and ambient air are 18.8% and 16.3% higher than that of the conventional vapor compression refrigeration system under varied conditions, respectively

  13. Mechanism of subcooled water flow boiling critical heat flux in a circular tube at high liquid Reynolds number

    International Nuclear Information System (INIS)

    Hata, K.; Fukuda, K.; Masuzaki, S.

    2014-01-01

    The subcooled boiling heat transfer and the steady state critical heat flux (CHF) in a vertical circular tube for the flow velocities (u=3.95 to 30.80 m/s) are systematically measured by the experimental water loop comprised of a multistage canned-type circulation pump with high pump head. The SUS304 test tube of inner diameter (d=6 mm) and heated length (L=59.5 mm) is used in this work. The outer surface temperatures of the SUS304 test tube with heating are observed by an infrared thermal imaging camera and a video camera. The subcooled boiling heat transfers for SUS304 test tube are compared with the values calculated by other workers' correlations for the subcooled boiling heat transfer. The influence of flow velocity on the subcooled boiling heat transfer and the CHF is investigated into details based on the experimental data. Nucleate boiling surface superheats at the CHF are close to the lower limit of the heterogeneous spontaneous nucleation temperature and the homogeneous spontaneous nucleation temperature. The dominant mechanism of the subcooled flow boiling CHF on the SUS304 circular tube is discussed at high liquid Reynolds number. On the other hand, theoretical equations for k-ε turbulence model in a circular tube of a 3 mm in diameter and a 526 mm long are numerically solved for heating of water on heated section of a 3 mm in diameter and a 67 mm long with various thicknesses of conductive sub-layer by using PHOENICS code under the same conditions as the experimental ones previously obtained considering the temperature dependence of thermo-physical properties concerned. The Platinum (Pt) test tube of inner diameter (d=3 mm) and heated length (L=66.5 mm) was used in this experiment. The thicknesses of conductive sub-layer from non-boiling regime to CHF are clarified. The thicknesses of conductive sub-layer at the CHF point are evaluated for various flow velocities. The experimental values of the CHF are also compared with the corresponding

  14. Peak pool boiling heat flux from horizontal cylinders in subcooled liquids

    International Nuclear Information System (INIS)

    Elkassabgi, Y.

    1986-01-01

    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 120 0 C. Photographs, and the data themselves, reveal that there are three distinct burnout mechanisms at different levels of subcooling. Three interpretive models provide the basis for accurate correlations of the present data, and data from the literature, in each of the three regimes. Burnout is dictated by condensation on the walls of the vapor jets and columns at low subcooling. In the intermediate regime, burnout is limited by natural convection which becomes very effective as vapor near the heater reduces boundary layer resistance. Burnout in the high-subcooling regime is independent of the level of subcoooling and is limited by the process of molecular effusion

  15. A computation method for mass flowrate predictions in critical flows of initially subcooled liquid in long channels

    International Nuclear Information System (INIS)

    Celata, G.P.; D'Annibale, F.; Farello, G.E.

    1985-01-01

    It is suggested a fast and accurate computation method for the prediction of mass flowrate in critical flows initially subcooled liquid from ''long'' discharge channels (high LID values). Starting from a previous very simple correlation proposed by the authors, further improvements in the model enable to widen the method reliability up to initial saturation conditions. A comparison of computed values with 145 experimental data regarding several investigations carried out at the Heat Transfer Laboratory (TERM/ISP, ENEA Casaccia) shows an excellent agreement. The computed data shifting from experimental ones is within ±10% for almost all data, with a slight increase towards low inlet subcoolings. The average error, for all the considered data, is 4,6%

  16. Swivel Joint For Liquid Nitrogen

    Science.gov (United States)

    Milner, James F.

    1988-01-01

    Swivel joint allows liquid-nitrogen pipe to rotate through angle of 100 degree with respect to mating pipe. Functions without cracking hard foam insulation on lines. Pipe joint rotates on disks so mechanical stress not transmitted to thick insulation on pipes. Inner disks ride on fixed outer disks. Disks help to seal pressurized liquid nitrogen flowing through joint.

  17. Automatic liquid nitrogen feeding device

    International Nuclear Information System (INIS)

    Gillardeau, J.; Bona, F.; Dejachy, G.

    1963-01-01

    An automatic liquid nitrogen feeding device has been developed (and used) in the framework of corrosion tests realized with constantly renewed uranium hexafluoride. The issue was to feed liquid nitrogen to a large capacity metallic trap in order to condensate uranium hexafluoride at the exit of the corrosion chambers. After having studied various available devices, a feeding device has been specifically designed to be robust, secure and autonomous, as well as ensuring a high liquid nitrogen flowrate and a highly elevated feeding frequency. The device, made of standard material, has been used during 4000 hours without any problem [fr

  18. Numerical Simulation of Liquid Nitrogen Chilldown of a Vertical Tube

    Science.gov (United States)

    Darr, Samuel; Hu, Hong; Schaeffer, Reid; Chung, Jacob; Hartwig, Jason; Majumdar, Alok

    2015-01-01

    This paper presents the results of a one-dimensional numerical simulation of the transient chilldown of a vertical stainless steel tube with liquid nitrogen. The direction of flow is downward (with gravity) through the tube. Heat transfer correlations for film, transition, and nucleate boiling, as well as critical heat flux, rewetting temperature, and the temperature at the onset of nucleate boiling were used to model the convection to the tube wall. Chilldown curves from the simulations were compared with data from 55 recent liquid nitrogen chilldown experiments. With these new correlations the simulation is able to predict the time to rewetting temperature and time to onset of nucleate boiling to within 25% for mass fluxes ranging from 61.2 to 1150 kg/(sq m s), inlet pressures from 175 to 817 kPa, and subcooled inlet temperatures from 0 to 14 K below the saturation temperature.

  19. Test of a cryogenic set-up for a 10 meter long liquid nitrogen cooled superconducting power cable

    DEFF Research Database (Denmark)

    Træholt, Chresten; Rasmussen, Carsten; Kühle (fratrådt), Anders Van Der Aa

    2000-01-01

    High temperature superconducting power cables may be cooled by a forced flow of sub-cooled liquid nitrogen. One way to do this is to circulate the liquid nitrogen (LN2) by means of a mechanical pump through the core of the cable and through a sub-cooler.Besides the cooling station, the cryogenics...... cable. We report on our experimental set-up for testing a 10 meter long high temperature superconducting cable with a critical current of 3.2 kA at 77K. The set-up consists of a custom designed cable end termination, current lead, coolant feed-through, liquid nitrogen closed loop circulation system...

  20. Experimental and theoretical studies on subcooled flow boiling of pure liquids and multicomponent mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Jamialahmadi, M.; Abdollahi, H.; Shariati, A. [The University of Petroleum Industry, Ahwaz (Iran); Mueller-Steinhagen, H. [Institute of Technical Thermodynamics, German Aerospace Center (Germany); Institute of Thermodynamics and Thermal Engineering, University of Stuttgart (Germany)

    2008-05-15

    To improve the design of modern industrial reboilers, accurate knowledge of boiling heat transfer coefficients is essential. In this study flow boiling heat transfer coefficients for binary and ternary mixtures of acetone, isopropanol and water were measured over a wide range of heat flux, subcooling, flow velocity and composition. The measurements cover the regimes of convective heat transfer, transitional boiling and fully developed subcooled flow boiling. Two models are presented for the prediction of flow boiling heat transfer coefficients. The first model is the combination of the Chen model with the Gorenflo correlation and the Schluender model for single and multicomponent boiling, respectively. This model predicts flow boiling heat transfer coefficients with acceptable accuracy, but fails to predict the nucleate boiling fraction NBF reasonably well. The second model is based on the asymptotic addition of forced convective and nucleate boiling heat transfer coefficients. The benefit of this model is a further improvement in the accuracy of flow boiling heat transfer coefficient over the Chen type model, simplicity and the more realistic prediction of the nucleate boiling fraction NBF. (author)

  1. Subcooled boiling heat transfer correlation to calculate the effects of dissolved gas in a liquid

    International Nuclear Information System (INIS)

    Zarkasi, Amin S.; Chao, W.W.; Kunze, Jay F.

    2004-01-01

    The water coolant in most operating power reactor systems is kept free of dissolved gas, so as to minimize corrosion. However, in most research reactors, which operate at temperatures below 70 deg. C, and between 1 and 5 atm. pressure, the dissolved gas remains present in the water coolant system during operation. This dissolved gas can have a significant effect during accident conditions (i.e. a LOCA), when the fluid quickly reaches boiling, coincident with flow stagnation and subsequent flow reversal. A benchmark experiment was conducted, with an electrically heated, closed loop channel, modeling a research reactor fuel coolant channels (2 mm thick). The results showed 'boiling (bubble) noise' occurring before wall temperatures reached saturation, and a significant increase (up to 50%) in the heat transfer coefficient in the subcooled boiling region when in the presence of dissolved gas, compared to degassed water. Since power reactors do not involve dissolved gas, the RELAP safety analysis code does not include any provisions for the effect of dissolved gas on heat transfer. In this work, the effects of the dissolved gas are evaluated for inclusion in the RELAP code, including provision for initiating 'nucleate boiling' at a lower temperature, and a provision for enhancing the heat transfer coefficient during the subcooled boiling region. Instead of relying on Chen's correlation alone, a modification of the superposition method of Bjorge was adopted. (author)

  2. The Joys of Liquid Nitrogen.

    Science.gov (United States)

    Nolan, William T.; Gish, Thaddeus J.

    1996-01-01

    Presents 6 short experiments with liquid nitrogen that 12- and 13-year-old students can safely perform under close supervision. Helps the students in learning a number of basic chemical principles while spurring their curiosity and showing them how much fun chemistry can be. (JRH)

  3. Subcooled boiling effect on dissolved gases behaviour

    International Nuclear Information System (INIS)

    Zmitko, M.; Sinkule, J.; Linek, V.

    1999-01-01

    A model describing dissolved gasses (hydrogen, nitrogen) and ammonia behaviour in subcooled boiling conditions of WWERs was developed. Main objective of the study was to analyse conditions and mechanisms leading to formation of a zone with different concentration of dissolved gases, eg. a zone depleted in dissolved hydrogen in relation to the bulk of coolant. Both, an equilibrium and dynamic approaches were used to describe a depletion of the liquid surrounding a steam bubble in the gas components. The obtained results show that locally different water chemistry conditions can be met in the subcooled boiling conditions, especially, in the developed subcooled boiling regime. For example, a 70% hydrogen depletion in relation to the bulk of coolant takes about 1 ms and concerns a liquid layer of 1 μn surrounding the steam bubble. The locally different concentration of dissolved gases can influence physic-chemical and radiolytic processes in the reactor system, eg. Zr cladding corrosion, radioactivity transport and determination of the critical hydrogen concentration. (author)

  4. Calculation of Steam Volume Fraction in Subcooled Boiling

    Energy Technology Data Exchange (ETDEWEB)

    Rouhani, S Z

    1967-06-15

    An analysis of subcooled boiling is presented. It is assumed that heat is removed by vapor generation, heating of the liquid that replaces the detached bubbles, and to some extent by single phase heat transfer. Two regions of subcooled boiling are considered and a criterion is provided for obtaining the limiting value of subcooling between the two regions. Condensation of vapor in the subcooled liquid is analysed and the relative velocity of vapor with respect to the liquid is neglected in these regions. The theoretical arguments result in some equations for the calculation of steam volume fraction and true liquid subcooling.

  5. Liquid nitrogen ingestion followed by gastric perforation.

    Science.gov (United States)

    Berrizbeitia, Luis D; Calello, Diane P; Dhir, Nisha; O'Reilly, Colin; Marcus, Steven

    2010-01-01

    Ingestion of liquid nitrogen is rare but carries catastrophic complications related to barotrauma to the gastrointestinal tract. We describe a case of ingestion of liquid nitrogen followed by gastric perforation and respiratory insufficiency and discuss the mechanism of injury and management of this condition. Liquid nitrogen is widely available and is frequently used in classroom settings, in gastronomy, and for recreational purposes. Given the potentially lethal complications of ingestion, regulation of its use, acquisition, and storage may be appropriate.

  6. Levitation of Liquid Microdroplets Above A Solid Surface Subcooled to the Leidenfrost Temperature

    Directory of Open Access Journals (Sweden)

    Kirichenko D. P.

    2016-01-01

    Full Text Available Evaporation of liquid microdroplets that fall on a solid surface with the temperature of below the Leidenfrost temperature is studied. It has been found out that sufficiently small liquid droplets of about 10 microns can suspend at some distance from the surface (levitate and do not reach the surface; at that, the rate of droplet evaporation is reduced by an order as compared to microdroplets, which touch the surface. It is determined that in contrast to microdroplets, which touch the surface, the specific evaporation rate of levitating droplets is constant in time.

  7. Characteristic evaluation of cooling technique using liquid nitrogen and metal porous media

    International Nuclear Information System (INIS)

    Tanno, Yusuke; Ito, Satoshi; Hashizume, Hidetoshi

    2014-01-01

    A remountable high-temperature superconducting magnet, whose segments can be mounted and demounted repeatedly, has been proposed for construction and maintenance of superconducting magnet and inner reactor components of a fusion reactor. One of the issues in this design is that the performance of the magnet deteriorates by a local temperature rise due to Joule heating in jointing regions. In order to prevent local temperature rise, a cooling system using a cryogenic coolant and metal porous media was proposed and experimental studies have been carried out using liquid nitrogen. In this study, flow and heat transfer characteristics of cooling system using subcooled liquid nitrogen and bronze particle sintered porous media are evaluated through experiments in which the inlet degree of subcooling and flow rate of the liquid nitrogen. The flow characteristics without heat input were coincided with Ergun’s equation expressing single-phase flow in porous materials. The obtained boiling curve was categorized into three conditions; convection region, nucleate boiling region and mixed region with nucleate and film boiling. Wall superheat did not increase drastically with porous media after departure from nucleate boiling point, which is different from a situation of usual boiling curve in a smooth tube. The fact is important characteristic to cooling superconducting magnet to avoid its quench. Heat transfer coefficient with bronze particle sintered porous media was at least twice larger than that without the porous media. It was also indicated qualitatively that departure from nucleate boiling point and heat transfer coefficient depends on degree of subcooling and mass flow rate. The quantitative evaluation of them and further discussion for the cooling system will be performed as future tasks

  8. Numerical Simulation and Analysis on Liquid Nitrogen Spray Heat Exchanger

    OpenAIRE

    Wenjing Ding; Weiwei Shan; Zijuan; Wang; Chao He

    2017-01-01

    Liquid spray heat exchanger is the critical equipment of temperature regulating system by gaseous nitrogen which realizes the environment temperature in the range of -180 ℃~+180 ℃. Liquid nitrogen is atomized into smaller liquid drops through liquid nitrogen sprayer and then contacts with gaseous nitrogen to be cooled. By adjusting the pressure of liquid nitrogen and gaseous nitrogen, the flowrate of liquid nitrogen is changed to realize the required outlet temperature of heat exchanger. The ...

  9. Subcooled boiling heat transfer in a short vertical SUS304-tube at liquid Reynolds number range 5.19 x 104 to 7.43 x 105

    International Nuclear Information System (INIS)

    Hata, Koichi; Masuzaki, Suguru

    2009-01-01

    The subcooled boiling heat transfer and the steady-state critical heat fluxes (CHFs) in a short vertical SUS304-tube for the flow velocities (u = 17.28-40.20 m/s), the inlet liquid temperatures (T in = 293.30-362.49 K), the inlet pressures (P in = 842.90-1467.93 kPa) and the exponentially increasing heat input (Q = Q 0 exp(t/τ), τ = 8.5 s) are systematically measured by the experimental water loop comprised of a multistage canned-type circulation pump with high pump head. The SUS304 test tubes of inner diameters (d = 3 and 6 mm), heated lengths (L = 33 and 59.5 mm), effective lengths (L eff = 23.3 and 49.1 mm), L/d (=11 and 9.92), L eff /d (=7.77 and 8.18), and wall thickness (δ = 0.5 mm) with average surface roughness (Ra = 3.18 μm) are used in this work. The inner surface temperature and the heat flux from non-boiling to CHF are clarified. The subcooled boiling heat transfer for SUS304 test tube is compared with our Platinum test tube data and the values calculated by other workers' correlations for the subcooled boiling heat transfer. The influence of flow velocity on the subcooled boiling heat transfer and the CHF is investigated into details and the widely and precisely predictable correlation of the subcooled boiling heat transfer for turbulent flow of water in a short vertical SUS304-tube is given based on the experimental data. The correlation can describe the subcooled boiling heat transfer obtained in this work within 15% difference. Nucleate boiling surface superheats for the SUS304 test tube become very high. Those at the high flow velocity are close to the lower limit of Heterogeneous Spontaneous Nucleation Temperature. The dominant mechanisms of the flow boiling CHF in a short vertical SUS304-tube are discussed.

  10. The boiling crisis in a subcooled liquid flowing in a vertical annular channel

    International Nuclear Information System (INIS)

    Passos, J.C.

    1989-01-01

    Experimental results concerning the critical heat flux density for a variety of forced flow conditions of Freon 113 in a circular annular channel of 3 mm width and 107 mm length when the inside wall is heated are presented. The flow configurations were also visualized prior and during the boiling crisis. For inlet liquid velocities equal or larger than 0.041 m/s, the correlated dimensionless data extends the range of validity of those of Katto for relatively much longer tubes. A simple balance of forces over a bubble attached to the wall shows that, for smaller velocities, the gravity effect has to be taken into account in the establishment of a more general correlation. (author)

  11. Development of liquid nitrogen Centrifugal Pump

    International Nuclear Information System (INIS)

    Abe, M; Sagiyama, R; Tsuchiya, H; Takayama, T; Torii, Y; Nakamura, M; Hoshino, Y; Odashima, Y

    2009-01-01

    Usually liquid nitrogen (LN 2 ) transfer from a container to a laboratory equipment takes place by applying pressure to the container to push out liquid or pouring liquid into the cryostat directly by lifting the container. In order to overcome inconvenience of pressuring or lifting containers, we have been developing the Liquid Nitrogen Centrifugal Pump of a small electric turbine pump. Significant advantages that both reducing time to fill LN 2 and controlling the flow rate of liquid into the cryostat are obtained by introducing this pump. We have achieved the lift of about 800mm with the vessel's opening diameter of 28mm.

  12. Determination of Meteorite Porosity Using Liquid Nitrogen

    Science.gov (United States)

    Kohout, T.; Kletetschka, G.; Pesonen, L. J.; Wasilewski, P. J.

    2005-01-01

    We introduce a new harmless method for porosity measurement suitable for meteorite samples. The method is a modification of the traditional Archimedean method based on immersion of the samples in a liquid medium like water or organic liquids. In our case we used liquid nitrogen for its chemically inert characteristics.

  13. The Bevatron liquid nitrogen circulation system

    International Nuclear Information System (INIS)

    Hunt, D.; Stover, G.

    1987-03-01

    A nitrogen liquefier and computer controlled valving system have been added to the Bevatron cryoliner vacuum system to cut operating costs by reducing liquid nitrogen consumption. The computer and interface electronic systems, which control the temperatures of twenty-eight liquid nitrogen circuits, have been chosen and designed to operate in the Bevatron's pulsating magnetic field. The nitrogen exhaust is routed back to a liquefier, of about five kilowatt capacity, liquefied, and rerouted through the cooling circuits. A description of the system and operating results are presented

  14. Automatic Transmission Of Liquid Nitrogen

    Directory of Open Access Journals (Sweden)

    Sumedh Mhatre

    2015-08-01

    Full Text Available Liquid Nitrogen is one of the major substance used as a chiller in industry such as Ice cream factory Milk Diary Storage of blood sample Blood Bank etc. It helps to maintain the required product at a lower temperature for preservation purpose. We cannot fully utilise the LN2 so practically if we are using 3.75 litre LN2 for a single day then around 12 of LN2 450 ml is wasted due to vaporisation. A pressure relief valve is provided to create a pressure difference. If there is no pressure difference between the cylinder carrying LN2 and its surrounding it will results in damage of container as well as wastage of LN2.Transmission of LN2 from TA55 to BA3 is carried manually .So care must be taken for the transmission of LN2 in order to avoid its wastage. With the help of this project concept the transmission of LN2 will be carried automatically so as to reduce the wastage of LN2 in case of manual operation.

  15. Specific cooling capacity of liquid nitrogen

    Science.gov (United States)

    Kilgore, R. A.; Adcock, J. B.

    1977-01-01

    The assumed cooling process and the method used to calculate the specific cooling capacity of liquid nitrogen are described, and the simple equation fitted to the calculated specific cooling capacity data, together with the graphical form calculated values of the specific cooling capacity of nitrogen for stagnation temperatures from saturation to 350 K and stagnation pressures from 1 to 10 atmospheres, are given.

  16. Liquid nitrogen cryotherapy of superior limbic keratoconjunctivitis.

    Science.gov (United States)

    Fraunfelder, Frederick W

    2009-02-01

    To evaluate the effects of liquid nitrogen cryotherapy on superior limbic keratoconjunctivitis (SLK). Interventional case series. In this clinical practice case series, the effects of liquid nitrogen cryotherapy on SLK were observed. Liquid nitrogen cryotherapy was performed using a Brymill E tip spray (0.013-inch aperture) with a double freeze-thaw technique. All subjects were outpatients who had local anesthesia with a single drop of topical proparacaine. The main outcome measure was the resolution of the disease process after treatment. Four female patients (average age, 64 +/- 13 years) and seven eyes with SLK were treated with liquid nitrogen cryotherapy. Resolution of signs and symptoms occurred within two weeks. Disease recurred in two patients and three of seven eyes, although repeat cryotherapy eradicated SLK in all cases. The repeat cryotherapy was performed at three months postoperatively. There were no adverse ocular events. Liquid nitrogen cryotherapy appears to be an effective alternative treatment for SLK as all subjects studied achieved long-term cures. Repeat cryotherapy may be necessary in some instances and may be performed three months after the first treatment.

  17. DNB heat flux on inner side of a vertical pipe in forced flow of liquid hydrogen and liquid nitrogen

    Science.gov (United States)

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

    2018-06-01

    Heat transfer from inner side of a heated vertical pipe to liquid hydrogen flowing upward was measured at the pressures of 0.4, 0.7 and 1.1 MPa for wide ranges of flow rate and liquid temperature. Nine test heaters with different inner diameters of 3, 4, 6 and 9 mm and the lengths of 50, 100, 150, 200, 250 and 300 mm were used. The DNB (departure from nucleate boiling) heat fluxes in forced flow of liquid hydrogen were measured for various subcoolings and flow velocities at pressures of 0.4, 0.7 and 1.1 MPa. Effect of L/d (ratio of heater length to diameter) was clarified for the range of L / d ⩽ 50 . A new correlation of DNB heat flux was presented based on a simple model and the experimental data. Similar experiments were performed for liquid nitrogen at pressures of 0.5 MPa and 1.0 MPa by using the same experimental system and some of the test heaters. It was confirmed that the new correlation can describe not only the hydrogen data, but also the data of liquid nitrogen.

  18. Liquid nitrogen dewar for protein crystal growth

    Science.gov (United States)

    2001-01-01

    Gaseous Nitrogen Dewar apparatus developed by Dr. Alex McPherson of the University of California, Irvine for use aboard Mir and the International Space Station allows large quantities of protein samples to be crystallized in orbit. The specimens are contained either in plastic tubing (heat-sealed at each end). Biological samples are prepared with a precipitating agent in either a batch or liquid-liquid diffusion configuration. The samples are then flash-frozen in liquid nitrogen before crystallization can start. On orbit, the Dewar is placed in a quiet area of the station and the nitrogen slowly boils off (it is taken up by the environmental control system), allowing the proteins to thaw to begin crystallization. The Dewar is returned to Earth after one to four months on orbit, depending on Shuttle flight opportunities. The tubes then are analyzed for crystal presence and quality

  19. Ceramic packages for liquid-nitrogen operation

    International Nuclear Information System (INIS)

    Tong, H.M.; Yeh, H.L.; Goldblatt, R.D.

    1989-01-01

    To evaluate their compatibility for use in a liquid-nitrogen computer, metallized ceramic packages with test chips joined using IBM controlled-collapse solder (Pb-Sn) technology have been cycled between 30 0 C and liquid-nitrogen temperature. Room-temperature electrical resistance measurements were made at regular intervals of cycles to determine whether solder failure accompanied by a significant resistance increase had occurred. For the failed solder joints characterized by the highest thermal shear strain amplitude of 3.3 percent, the authors were able to estimate the number of liquid-nitrogen cycles needed to produce the corresponding failure rate using a room-temperature solder lifetime model. Cross-sectional examination of the failed solder joints using scanning electron microscopy and energy dispersive X-ray analysis indicated solder cracking occurring at the solder-ceramic interface. Chip pull tests on cycled packages yielded strengths far exceeding the minimal requirement. Mechanisms involving the formation of intermetallics were proposed to account for the observed solder fracture modes after liquid-nitrogen cycling and after chip pull. Furthermore, scanning electron microscopic examination of pulled chips in cycled packages showed no apparent sign of cracking in quartz and polyimide for chip insulation

  20. Liquid-Nitrogen Test for Blocked Tubes

    Science.gov (United States)

    Wagner, W. R.

    1984-01-01

    Nondestructive test identifies obstructed tube in array of parallel tubes. Trickle of liquid nitrogen allowed to flow through tube array until array accumulates substantial formation of frost from moisture in air. Flow stopped and warm air introduced into inlet manifold to heat tubes in array. Tubes still frosted after others defrosted identified as obstructed tubes. Applications include inspection of flow systems having parallel legs.

  1. Evaluation of the dependence of heat transfer coefficient on the particle diameter of a metal porous medium in a heat removal system using liquid nitrogen

    International Nuclear Information System (INIS)

    Sasaki, Shunsuke; Ito, Satoshi; Hashizume, Hidetoshi

    2015-01-01

    Cryogenic cooling system using a bronze-particle-sintered porous medium has been studied for a re mountable high-temperature superconducting magnet. This study evaluates boiling curve of subcooled liquid nitrogen as flowing in a bronze porous medium as a function of the particle diameter of the medium. We obtained Departure from Nuclear Boiling (Dnb) point from the boiling curve and discussed growth of nitrogen vapor bubble inferred from measured pressure drop. The pressure drop decreased significantly at wall superheat before reaching the DNB point whereas that slightly decreased after reaching the DNB point compared to the smallest wall superheat. This result could consider DNB rises with an increase in the particle diameter because larger particle makes vapor to move easily from the heated pore region. The influence of the particle diameter on the heat transfer performance is larger than that of coolant's degree of subcooling. (author)

  2. Vitrification and levitation of a liquid droplet on liquid nitrogen.

    Science.gov (United States)

    Song, Young S; Adler, Douglas; Xu, Feng; Kayaalp, Emre; Nureddin, Aida; Anchan, Raymond M; Maas, Richard L; Demirci, Utkan

    2010-03-09

    The vitrification of a liquid occurs when ice crystal formation is prevented in the cryogenic environment through ultrarapid cooling. In general, vitrification entails a large temperature difference between the liquid and its surrounding medium. In our droplet vitrification experiments, we observed that such vitrification events are accompanied by a Leidenfrost phenomenon, which impedes the heat transfer to cool the liquid, when the liquid droplet comes into direct contact with liquid nitrogen. This is distinct from the more generally observed Leidenfrost phenomenon that occurs when a liquid droplet is self-vaporized on a hot plate. In the case of rapid cooling, the phase transition from liquid to vitrified solid (i.e., vitrification) and the levitation of droplets on liquid nitrogen (i.e., Leidenfrost phenomenon) take place simultaneously. Here, we investigate these two simultaneous physical events by using a theoretical model containing three dimensionless parameters (i.e., Stefan, Biot, and Fourier numbers). We explain theoretically and observe experimentally a threshold droplet radius during the vitrification of a cryoprotectant droplet in the presence of the Leidenfrost effect.

  3. Liquid Nitrogen Zero Boiloff Testing

    Science.gov (United States)

    Plachta, David; Feller, Jeffrey; Johnson, Wesley; Robinson, Craig

    2017-01-01

    Cryogenic propellants such as liquid hydrogen (LH2) and liquid oxygen (LO2) are a part of NASAs future space exploration due to their high specific impulse for rocket motors of upper stages suitable for transporting 10s to 100s of metric tons of payload mass to destinations outside of low earth orbit and for their return. However, the low storage temperatures of LH2 and LO2 cause substantial boil-off losses for missions with durations greater than several months. These losses can be eliminated by incorporating high performance cryocooler technology to intercept heat load to the propellant tanks and modulating the cryocooler to control tank pressure. The active thermal control technology being developed by NASA is the reverse turbo-Brayton cycle cryocooler and its integration to the propellant tank through a distributed cooling tubing network coupled to the tank wall. This configuration was recently tested at NASA Glenn Research Center, in a vacuum chamber and cryo-shroud that simulated the essential thermal aspects of low Earth orbit, its vacuum and temperature. Testing consisted of three passive tests with the active cryo-cooler system off, and 7 active tests, with the cryocooler powered up. The test matrix included zero boil-off tests performed at 90 full and 25 full, and several demonstrations at excess cooling capacity and reduced cooling capacity. From this, the tank pressure response with varied cryocooler power inputs was determined. This test series established that the active cooling system integrated with the propellant tank eliminated boil-off and robustly controlled tank pressure.

  4. Condensation of vapor bubble in subcooled pool

    Science.gov (United States)

    Horiuchi, K.; Koiwa, Y.; Kaneko, T.; Ueno, I.

    2017-02-01

    We focus on condensation process of vapor bubble exposed to a pooled liquid of subcooled conditions. Two different geometries are employed in the present research; one is the evaporation on the heated surface, that is, subcooled pool boiling, and the other the injection of vapor into the subcooled pool. The test fluid is water, and all series of the experiments are conducted under the atmospheric pressure condition. The degree of subcooling is ranged from 10 to 40 K. Through the boiling experiment, unique phenomenon known as microbubble emission boiling (MEB) is introduced; this phenomenon realizes heat flux about 10 times higher than the critical heat flux. Condensation of the vapor bubble is the key phenomenon to supply ambient cold liquid to the heated surface. In order to understand the condensing process in the MEB, we prepare vapor in the vapor generator instead of the evaporation on the heated surface, and inject the vapor to expose the vapor bubble to the subcooled liquid. Special attention is paid to the dynamics of the vapor bubble detected by the high-speed video camera, and on the enhancement of the heat transfer due to the variation of interface area driven by the condensation.

  5. A visual study of radial inward choked flow of liquid nitrogen.

    Science.gov (United States)

    Hendricks, R. C.; Simoneau, R. J.; Hsu, Y. Y.

    1973-01-01

    Data and high speed movies were acquired on pressurized subcooled liquid nitrogen flowing radially inward through a 0.0076 cm gap. The stagnation pressure ranged from 0.7 to 4 MN/sq m. Steady radial inward choked flow appears equivalent to steady choked flow through axisymmetric nozzles. Transient choked flows through the radial gap are not uniform and the discharge pattern appears as nonuniform impinging jets. The critical mass flow rate data for the transient case appear different from those for the steady case. On the mass flow rate vs pressure map, the slope and separation of the isotherms appear to be less for transient than for steady radial choked flow.

  6. Correlation of Helium Solubility in Liquid Nitrogen

    Science.gov (United States)

    VanDresar, Neil T.; Zimmerli, Gregory A.

    2012-01-01

    A correlation has been developed for the equilibrium mole fraction of soluble gaseous helium in liquid nitrogen as a function of temperature and pressure. Experimental solubility data was compiled and provided by National Institute of Standards and Technology (NIST). Data from six sources was used to develop a correlation within the range of 0.5 to 9.9 MPa and 72.0 to 119.6 K. The relative standard deviation of the correlation is 6.9 percent.

  7. Ice plugging of pipes using liquid nitrogen

    International Nuclear Information System (INIS)

    Twigg, R.J.

    1987-03-01

    This report presents a study on the ice plugging of pipe using liquid nitrogen, and is based on a literature review and on discussions with individuals who use the technique. Emphasis is placed on ferritic alloys, primarily carbon steels, in pipe sized up to 60 cm in diameter and on austenitic stainless steels in pipe sizes up to 30 cm in diameter. This technique is frequently used for leak testing in nuclear facilities

  8. Foil bearing performance in liquid nitrogen and liquid oxygen

    Science.gov (United States)

    Genge, Gary G.; Saville, Marshall; Gu, Alston

    1993-01-01

    Space transfer vehicles and other power and propulsion systems require long-life turbopumps. Rolling-element bearings used in current turbopumps do not have sufficient life for these applications. Process fluid foil bearings have established long life, with exceptional reliability, over a wide range of temperatures and fluids in many high-speed turbomachinery applications. However, actual data on bearing performance in cryogenic fluids has been minimal. The National Aeronautics and Space Administration (NASA) and AlliedSignal Aerospace Systems and Equipment (ASE) have attempted to characterize the leaf-type compliant foil bearing in oxygen and nitrogen. The work performed under a joint internal research and development program between Marshall Space Flight Center (MSFC) and ASE demonstrated that the foil bearing has load capacities of at least 266 psi in liquid oxygen and 352 psi in liquid nitrogen. In addition, the bearing demonstrated a direct damping coefficient of 40 to 50 lb-sec/in. with a damping ratio of .7 to 1.4 in. liquid nitrogen using a bearing sized for upper-stage turbopumps. With the results from this testing and the years of successful use in air cycle machines and other applications, leaf-type compliant foil bearings are ready for testing in liquid oxygen turbopumps.

  9. Liquid nitrogen fire extinguishing system test report

    International Nuclear Information System (INIS)

    Beidelman, J.A.

    1972-01-01

    The objective of this test series was to demonstrate the feasibility of using liquid nitrogen as a fire-extinguishing agent for certain types of metal fires. It was intended to provide data and experience appropriate to the design of a second series which will test the applicability of this technique to plutonium fires and which will develop more detailed operating information and permit more precise measurement of test parameters-oxygen depletion rates and equilibrium concentrations, temperature effects, and nitrogen pressures, flow rates, spray methods and patterns, etc. The test series was directed specifically toward extinguishment of metal fires occurring in well-confined areas and was not intended to be representative of any larger classification. Fires of several types were tested, e.g., magnesium, mixed magnesium and zirconium, sodium and cerium

  10. Sorption Properties of Aerogel in Liquid Nitrogen

    Science.gov (United States)

    Johnson, Wesley L.

    2006-01-01

    Aerogel products are now available as insulation materials of the future. The Cryogenics Test Laboratory at the NASA Kennedy Space Center is developing aerogel-based thermal insulation systems for space launch applications. Aerogel beads (Cabot Nanogel ) and aerogel blankets (Aspen Aerogels Spaceloft ) have outstanding ambient pressure thermal performance that makes them useful for applications where sealing is not possible. Aerogel beads are open-celled silicone dioxide and have tiny pores that run throughout the body of the bead. It has also recently been discovered that aerogel beads can be used as a filtering device for aqueous compounds at room temperature. With their hydrophobic covering, the beads absorb any non-polar substance and they can be chemically altered to absorb hot gases. The combination of the absorption and cryogenic insulating properties of aerogel beads have never been studied together. For future cryogenic insulation applications, it is crucial to know how the beads react while immersed in cryogenic liquids, most notably liquid nitrogen. Aerogel beads in loose-fill situation and aerogel blankets with composite fiber structure have been tested for absorption properties. Depending on the type of aerogel used and the preparation, preliminary results show the material can absorb up to seven times its own weight of liquid nitrogen, corresponding to a volumetric ratio of 0.70 (unit volume nitrogen per unit volume aerogel). These tests allow for an estimate on how much insulation is needed in certain situations. The theory behind the different processes of sorption is necessary for a better understanding of the preparation of the beads before they are used in an insulation system.

  11. Liquid Nitrogen Removal of Critical Aerospace Materials

    Science.gov (United States)

    Noah, Donald E.; Merrick, Jason; Hayes, Paul W.

    2005-01-01

    Identification of innovative solutions to unique materials problems is an every-day quest for members of the aerospace community. Finding a technique that will minimize costs, maximize throughput, and generate quality results is always the target. United Space Alliance Materials Engineers recently conducted such a search in their drive to return the Space Shuttle fleet to operational status. The removal of high performance thermal coatings from solid rocket motors represents a formidable task during post flight disassembly on reusable expended hardware. The removal of these coatings from unfired motors increases the complexity and safety requirements while reducing the available facilities and approved processes. A temporary solution to this problem was identified, tested and approved during the Solid Rocket Booster (SRB) return to flight activities. Utilization of ultra high-pressure liquid nitrogen (LN2) to strip the protective coating from assembled space shuttle hardware marked the first such use of the technology in the aerospace industry. This process provides a configurable stream of liquid nitrogen (LN2) at pressures of up to 55,000 psig. The performance of a one-time certification for the removal of thermal ablatives from SRB hardware involved extensive testing to ensure adequate material removal without causing undesirable damage to the residual materials or aluminum substrates. Testing to establish appropriate process parameters such as flow, temperature and pressures of the liquid nitrogen stream provided an initial benchmark for process testing. Equipped with these initial parameters engineers were then able to establish more detailed test criteria that set the process limits. Quantifying the potential for aluminum hardware damage represented the greatest hurdle for satisfying engineers as to the safety of this process. Extensive testing for aluminum erosion, surface profiling, and substrate weight loss was performed. This successful project clearly

  12. Excitation of cavitation bubbles in low-temperature liquid nitrogen

    Science.gov (United States)

    Sasaki, Koichi; Harada, Shingo

    2017-06-01

    We excited a cavitation bubble by irradiating a Nd:YAG laser pulse onto a titanium target that was installed in liquid nitrogen at a temperature below the boiling point. To our knowledge, this is the first experiment in which a cavitation bubble has been successfully excited in liquid nitrogen. We compared the cavitation bubble in liquid nitrogen with that in water on the basis of an equation reported by Florschuetz and Chao [J. Heat Transfer 87, 209 (1965)].

  13. Bubble behaviour and mean diameter in subcooled flow boiling

    Energy Technology Data Exchange (ETDEWEB)

    Zeitoun, O.; Shoukri, M. [McMaster Univ., Hamilton, Ontario (Canada)

    1995-09-01

    Bubble behaviour and mean bubble diameter in subcooled upward flow boiling in a vertical annular channel were investigated under low pressure and mass flux conditions. A high speed video system was used to visualize the subcooled flow boiling phenomenon. The high speed photographic results indicated that, contrary to the common understanding, bubbles tend to detach from the heating surface upstream of the net vapour generation point. Digital image processing technique was used to measure the mean bubble diameter along the subcooled flow boiling region. Data on the axial area-averaged void fraction distributions were also obtained using a single beam gamma densitometer. Effects of the liquid subcooling, applied heat flux and mass flux on the mean bubble size were investigated. A correlation for the mean bubble diameter as a function of the local subcooling, heat flux and mass flux was obtained.

  14. Vapor Explosions with Subcooled Freon

    International Nuclear Information System (INIS)

    Henry, R.E.; Fauske, Hans K.; McUmber, L.M.

    1976-01-01

    resulting from the poor wetting between Freon and water. However, the experimental data do demonstrate a definite threshold behavior at a water temperature of approximately 45 deg. C, and this value has been observed by other experimenters with the same fluids. 6 The Freon-mineral systems exhibited excellent agreement with the interface temperature model where the spontaneous nucleation behavior was assumed to be homogeneous because of the affinity between Freons and oils. The applicability of the interface temperature model was investigated by varying the initial subcooling of the Freon in a Freon-22 and water system. The intent of these experiments was to change the interface temperature with the subcooling of the Freon and observe the resulting changes in the explosive behavior of the system. The conclusion of these experiments was that the explosive behavior did not change with increasing Freon subcooling and hence with changing interface temperature. This particular system has two inherent disadvantages which tend to cloud the experimental results. The first is that the excellent thermal properties of the water, compared to those of the Freon, significantly reduce the sensitivity of the interface temperature to Freon subcooling, and the second is that since one is already dealing with a poorly wetted system, the wetting characteristics can be altered by changing the interface temperature which in turn changes the heterogeneous nucleation temperature. To provide a more definitive test of the interface temperature representation by subcooling the cold liquid, a system of Freon-22 and mineral oil, which presents a well-wetted system, is utilized in this set of experiments. In addition to the better wetting characteristics, the thermal conductivity, density, and specific heat of the mineral oil are less than those of the water which results in a greater sensitivity of this particular system to changes in the initial subcooling of the Freon. Also, the better wetting in this

  15. Removing Spilled Oil With Liquid Nitrogen

    Science.gov (United States)

    Snow, Daniel B.

    1991-01-01

    Technique proposed to reduce more quickly, contain, clean up, and remove petroleum products and such other pollutants as raw sewage and chemicals without damage to humans, animals, plants, or the environment. Unique and primary aspect of new technique is use of cryogenic fluid to solidify spill so it can be carried away in solid chunks. Liquid nitrogen (LN2), with boiling point at -320 degrees F (-196 degrees C), offers probably best tradeoff among extreme cold, cost, availability, and lack of impact on environment among various cryogenic fluids available. Other applications include extinguishing fires at such locations as oil derricks or platforms and at tank farms containing such petroleum products as gasoline, diesel fuel, and kerosene.

  16. The automatic liquid nitrogen filling system for GDA detectors

    Indian Academy of Sciences (India)

    . Abstract. An indigenously developed automatic liquid nitrogen (LN2) filling system has been installed in gamma detector array (GDA) facility at Nuclear Science Centre. Electro-pneumatic valves are used for filling the liquid nitrogen into the ...

  17. Mount makes liquid nitrogen-cooled gamma ray detector portable

    Science.gov (United States)

    Fessler, T. E.

    1966-01-01

    Liquid nitrogen-cooled gamma ray detector system is made portable by attaching the detector to a fixture which provides a good thermal conductive path between the detector and the liquid nitrogen in a dewar flask and a low heat leak path between the detector and the external environment.

  18. Liquid nitrogen cryotherapy for surface eye disease (an AOS thesis).

    Science.gov (United States)

    Fraunfelder, Frederick Web

    2008-01-01

    To evaluate the effects of new treatments with liquid nitrogen cryotherapy on some external eye conditions. In this retrospective case study, 6 separate series from a single tertiary care referral center practice are described. Liquid nitrogen cryotherapy was used to treat conjunctival amyloidosis, primary pterygia, recurrent pterygia, advancing wavelike epitheliopathy (AWLE), superior limbic keratoconjunctivitis (SLK), and palpebral vernal keratoconjunctivitis (VKC). The main outcome measure was the resolution of the disease process after treatment. Four patients with primary localized conjunctival amyloidosis were treated with liquid nitrogen cryotherapy. Two of them had recurrence of the amyloidosis, which cleared with subsequent treatment. Eighteen patients with primary pterygia had excision and cryotherapy with 1 recurrence. Of 6 subjects who presented with recurrent pterygia, 4 had a second recurrence after excision and cryotherapy. In 5 patients with AWLE, the condition resolved within 2 weeks without recurrence or the need for subsequent cryotherapy. Four patients with SLK were treated with liquid nitrogen cryotherapy. Disease recurred in 2 patients and 3 of 7 eyes, although subsequent cryotherapy eradicated SLK in all cases. Two patients and 3 eyelids with palpebral VKC were treated with liquid nitrogen cryotherapy. VKC recurred in all cases. Liquid nitrogen cryotherapy to the surface of the eye is effective in treating AWLE, and SLK. Excision followed by cryotherapy is successful in treating conjunctival amyloidosis and primary pterygia Liquid nitrogen cryotherapy is unsuccessful in the treatment of recurrent pterygia and VKC.

  19. Study on onset of nucleate boiling and net vapor generation point in subcooled flow boiling

    International Nuclear Information System (INIS)

    Ohtake, Hiroyasu; Wada, Noriyoshi; Koizumi, Yasuo

    2002-01-01

    The onset of nucleate boiling (ONB) and the point of net vapor generation on subcooled flow boiling, focusing on liquid subcooling and liquid velocity were investigated experimentally and analytically. Experiments were conducted using a copper thin-film (35μm) and subcooled water in a range of the liquid velocity from 0.27 to 4.6 m/s at 0.10MPa. The liquid subcoolings were 20, 30 and 40K, respectively. Temperatures at the onset of nucleate boiling obtained in the experiments increased with the liquid subcoolings and the liquid velocities. The increases in the temperature of ONB were represented with the classical stability theory of preexisting nuclei. The measured results of the net vapor generation agreed well with the results of correlation by Saha and Zuber in the range of the present experiments. (J.P.N.)

  20. Performance enhancement of a subcooled cold storage air conditioning system

    International Nuclear Information System (INIS)

    Hsiao, M.-J.; Cheng, C.-H.; Huang, M.-C.; Chen, S.-L.

    2009-01-01

    This article experimentally investigates the enhancement of thermal performance for an air conditioning system utilizing a cold storage unit as a subcooler. The cold storage unit is composed of an energy storage tank, liquid-side heat exchanger, suction-side heat exchanger and energy storage material (ESM), water. When the cooling load is lower than the nominal cooling capacity of the system, the cold storage unit can store extra cold energy of the system to subcool the condenser outlet refrigerant. Hence, both the cooling capacity and coefficient of performance (COP) of the system will be increased. This experiment tests the two operation modes: subcooled mode with energy storage and non-subcooled mode without energy storage. The results show that for fixed cooling loads at 3.05 kW, 3.5 kW and 3.95 kW, the COP of the subcooled mode are 16.0%, 15.6% and 14.1% higher than those of the non-subcooled mode, respectively. In the varied cooling load experiments, the COP of the subcooled cold storage air conditioning system is 15.3% higher than the conventional system.

  1. Control of nitrogen concentration in liquid lithium by hot trapping

    International Nuclear Information System (INIS)

    Sakurai, Toshiharu; Yoneoka, Toshiaki; Tanaka, Satoru; Suzuki, Akihiro; Muroga, Takeo

    2002-01-01

    Nitrogen concentration in liquid lithium was controlled by the method of hot trapping. V-Ti alloy and chromium were used as nitrogen gettering materials. Chromium is known to form ternary nitride with lithium. Gettering experiments were conducted at 823 K for 0.8-2.2 Ms. Under high nitrogen concentration in liquid lithium, above 10 -2 mass%, nitrogen gettering effect of chromium was found to be larger than that of V-10at.% Ti alloy. Nitrogen gettering by chromium at 823 K reached a limit at about 6.5x10 -3 mass% of nitrogen concentration in liquid lithium. Instability of ternary nitride of chromium and lithium below this nitrogen concentration in liquid lithium was considered to be the reason for this limit. The composition of the ternary nitride that was formed in this study was considered to be Li 6 Cr(III) 3 N 5 . In addition, immersion experiments of yttrium with V-10at.% Ti alloy were performed. It was found that nitriding of yttrium in liquid lithium is controlled by nitrogen gettering effect of V-10at.% Ti alloy

  2. Explosion hazard in liquid nitrogen cooled fusion systems

    International Nuclear Information System (INIS)

    Brereton, S.J.

    1988-01-01

    The explosion hazard associated with the use of liquid nitrogen in a radiation environment in fusion facilities has been investigated. The principal product of irradiating liquid nitrogen is thought to be ozone, resulting from the action of radiation on oxygen impurity. Ozone is a very unstable material, and explosions may occur as it rapidly decomposes to oxygen. Occurrences of this problem in irradiated liquid nitrogen systems are reviewed. An empirical expression, from early experiments, for the yield of ozone in liquid nitrogen-oxygen mixtures exposed to gamma radiation is employed to assess the degree of ozone explosion hazard expected at fusion facilities. The problem is investigated for the Compact Ignition Tokamak (CIT) as a particular example. 16 refs., 5 figs., 1 tab

  3. Electronic circuit provides automatic level control for liquid nitrogen traps

    Science.gov (United States)

    Turvy, R. R.

    1968-01-01

    Electronic circuit, based on the principle of increased thermistor resistance corresponding to decreases in temperature provides an automatic level control for liquid nitrogen cold traps. The electronically controlled apparatus is practically service-free, requiring only occasional reliability checks.

  4. Complete equation of state for shocked liquid nitrogen: Analytical developments

    International Nuclear Information System (INIS)

    Winey, J. M.; Gupta, Y. M.

    2016-01-01

    The thermodynamic response of liquid nitrogen has been studied extensively, in part, due to the long-standing interest in the high pressure and high temperature dissociation of shocked molecular nitrogen. Previous equation of state (EOS) developments regarding shocked liquid nitrogen have focused mainly on the use of intermolecular pair potentials in atomistic calculations. Here, we present EOS developments for liquid nitrogen, incorporating analytical models, for use in continuum calculations of the shock compression response. The analytical models, together with available Hugoniot data, were used to extrapolate a low pressure reference EOS for molecular nitrogen [Span, et al., J. Phys. Chem. Ref. Data 29, 1361 (2000)] to high pressures and high temperatures. Using the EOS presented here, the calculated pressures and temperatures for single shock, double shock, and multiple shock compression of liquid nitrogen provide a good match to the measured results over a broad range of P-T space. Our calculations provide the first comparison of EOS developments with recently-measured P-T states under multiple shock compression. The present EOS developments are general and are expected to be useful for other liquids that have low pressure reference EOS information available.

  5. Vitrification and levitation of a liquid droplet on liquid nitrogen

    OpenAIRE

    Song, Young S.; Adler, Douglas; Xu, Feng; Kayaalp, Emre; Nureddin, Aida; Anchan, Raymond M.; Maas, Richard L.; Demirci, Utkan

    2010-01-01

    The vitrification of a liquid occurs when ice crystal formation is prevented in the cryogenic environment through ultrarapid cooling. In general, vitrification entails a large temperature difference between the liquid and its surrounding medium. In our droplet vitrification experiments, we observed that such vitrification events are accompanied by a Leidenfrost phenomenon, which impedes the heat transfer to cool the liquid, when the liquid droplet comes into direct contact with liquid nitroge...

  6. Modeling of subcooled boiling in the vertical flow

    International Nuclear Information System (INIS)

    Koncar, B.; Mavko, B.

    1999-01-01

    A two-dimensional model of subcooled boiling in a vertical channel was developed. Its basic idea is that the vapor phase generation has a similar effect on the flow field as a hypothetical liquid phase generation. The bubble volume, generated due to evaporation process, was filled with liquid and included as a source term in the continuity equation for the liquid phase. Thus, the single-phase from of transport equations was preserved and bubbles were retained in the boundary layer near the heated surface. Time development of subcooled boiling was simulated and effects of governing physical mechanisms (evaporation, condensation, vapor-phase convection, vapor-phase diffusion) on the flow field and pressure drop were analyzed. The Results of the proposed two-dimensional model were compared with experimental data and RELAP5/MOD3.2 calculations. The presented model represents a contribution to the two-dimensional simulation of the subcooled boiling phenomenon.(author)

  7. Liquid to gas leak ratios with liquid nitrogen and liquid helium

    International Nuclear Information System (INIS)

    Batzer, T.H.; Call, W.R.

    1985-01-01

    To predict the leak rates of liquid helium and liquid nitrogen containers at operating conditions we need to know how small leaks (10 -8 to 10 -5 atm-cm 3 air/s), measured at standard conditions, behave when flooded with these cryogens. Two small leaks were measured at ambient conditions (approx.750 Torr and 295 K), at the normal boiling points of LN 2 and LHe, and at elevated pressures above the liquids. The ratios of the leak rates of the liquids at ambient pressure to the gases (G) at ambient pressure and room temperature were: GN 2 (1), LN 2 (18), GHe(1), and LHe(172). The leak rate ratio of LN 2 at elevated pressure was linear with pressure. The leak rate ratio of LHe at elevated pressure was also linear with pressure

  8. Liquid to gas leak ratios with liquid nitrogen and liquid helium

    International Nuclear Information System (INIS)

    Batzer, T.H.; Call, W.R.

    1985-01-01

    To predict the leak rates of liquid helium and liquid nitrogen containers at operating conditions we need to know how small leaks (10 -8 to 10 -5 atm-cm 3 air/s), measured at standard conditions, behave when flooded with these cryogens. Two small leaks were measured at ambient conditions (about 750 Torr and 295 K), at the normal boiling points of LN 2 and LHe, and at elevated pressures above the liquids. The ratios of the leak rates of the liquids at ambient pressure to the gases at ambient pressure and room temperature are presented. The leak rate ratio of LN 2 at elevated pressure was linear with pressure. The leak rate ratio of LHe at elevated pressure was also linear with pressure

  9. Experimental study of nitrogen oxide absorption by a liquid nitrogen tetroxide flow

    International Nuclear Information System (INIS)

    Verzhinskaya, A.B.; Saskovets, V.V.; Borovik, T.F.

    1984-01-01

    The system of N 2 O 4 based coolant regeneration needs productive and efficient absorbers, providing effective production of nitrogen oxide, decreasing upon NPP operation at the expense of radiation-thermal decomposition. The experimental istallation flowsheet for studying the nitrogen oxide absorbtion by liquid nitrogen tetroxide is given. The experiments have been carried out in removable test sections, looked like helical tubes with internal steam-and-liquid mixture flow and external water cooling. Six test sections with variable geometry factors have been manufactured. The plotted results of the experiments are given as dependences of extraction level and mass transfer volumetric coefficients on the geometry factor, pressure and Froude number

  10. Design Optimization of Liquid Nitrogen Based IQF Tunnel

    Science.gov (United States)

    Datye, A. B.; Narayankhedkar, K. G.; Sharma, G. K.

    2006-04-01

    A design methodology for an Individual Quick Freezing (IQF) tunnel using liquid nitrogen is developed and the design based on this methodology is validated using the data of commercial tunnels. The design takes care of heat gains due to the conveyor belt which is exposed to atmosphere at the infeed and outfeed ends. The design also considers the heat gains through the insulation as well as due to circulating fans located within the tunnel. For minimum liquid nitrogen consumption, the ratio of the length of the belt, L (from infeed to out feed) to the width of the belt, W can be considered as a parameter. The comparison of predicted and reported liquid nitrogen (experimental data) consumption shows good agreement and is within 10 %.

  11. Fast Conversion of Ionic Liquids and Poly(Ionic Liquid)s into Porous Nitrogen-Doped Carbons in Air.

    Science.gov (United States)

    Men, Yongjun; Ambrogi, Martina; Han, Baohang; Yuan, Jiayin

    2016-04-08

    Ionic liquids and poly(ionic liquid)s have been successfully converted into nitrogen-doped porous carbons with tunable surface area up to 1200 m²/g at high temperatures in air. Compared to conventional carbonization process conducted under inert gas to produce nitrogen-doped carbons, the new production method was completed in a rather shorter time without noble gas protection.

  12. Observation and modeling of 222Rn daughters in liquid nitrogen

    International Nuclear Information System (INIS)

    Frodyma, N.; Pelczar, K.; Wójcik, M.

    2014-01-01

    The results of alpha spectrometric measurements of the activity of 222 Rn daughters dissolved in liquefied nitrogen are presented. A direct detection method of ionized alpha-emitters from the 222 Rn decay chain ( 214 Po and 218 Po) in a cryogenic liquid in the presence of an external electric field is shown. Properties of the radioactive ions are derived from a proposed model of ion production and transport in the cryogenic liquid. Ionic life-time of the ions was found to be on the order of 10 s in liquid nitrogen (4.0 purity class). The presence of positive and negative ions was observed. - Highlights: • A direct detection method of the alpha-emitters in a cryogenic liquid is shown. • We examine electrostatic drifting of the radioactive ions in liquid nitrogen. • The ions belong to the Radon-222 decay chain; Radon-222 is dissolved in the liquid. • The model of the ions production and behaviour in the liquid is proposed. • The ion production significantly depends on the nuclear decay type (alpha or beta)

  13. Behaviour of uranium dioxide in liquid nitrogen tetraoxide

    International Nuclear Information System (INIS)

    Kobets, L.V.; Klavsut', G.N.; Dolgov, V.M.

    1983-01-01

    Interaction kinetics of uranium dioxide with liquid nitrogen tetroxide at 25-150 deg C has been studied. It is shown that in the temperature range studied NO[UO 2 (NO 3 ) 3 ] is the final product of the reaction. With the increase of specific surface of uranium dioxide and with the temperature increase the degree of oxide transformation increases. Uranium dioxide-liquid N 2 O 4 interaction proceeds in the diffusion region. Seeming activation energies and rate constants of the mentioned processes are calculated. Effect of nitrogen trioxide additions on transformation kinetics is considered

  14. Electrical conductivity measurements in shock compressed liquid nitrogen

    International Nuclear Information System (INIS)

    Hamilton, D.C.; Mitchell, A.C.; Nellis, W.J.

    1985-06-01

    The electrical conductivity of shock compressed liquid nitrogen was measured in the pressure range 20 to 50 GPa using a two-stage light-gas gun. The conductivities covered a range 4 x 10 -2 to 1 x 10 2 ohm -1 cm -1 . The data are discussed in terms of a liquid semiconductor model below the onset of the dissociative phase transition at 30 GPa. 15 refs., 1 fig

  15. Absorption and oxidation of nitrogen oxide in ionic liquids

    DEFF Research Database (Denmark)

    Kunov-Kruse, Andreas Jonas; Thomassen, Peter Langelund; Riisager, Anders

    2016-01-01

    A new strategy for capturing nitrogen oxide, NO, from the gas phase is presented. Dilute NO gas is removed from the gas phase by ionic liquids under ambient conditions. The nitrate anion of the ionic liquid catalyzes the oxidation of NO to nitric acid by atmospheric oxygen in the presence of water....... The nitric acid is absorbed in the ionic liquid up to approximately one mole HNO3 per mole of the ionic liquid due to the formation of hydrogen bonds. The nitric acid can be desorbed by heating, thereby regenerating the ionic liquid with excellent reproducibility. Here, time-resolved in-situ spectroscopic...... investigations of the reaction and products are presented. The procedure reveals a new vision for removing the pollutant NO by absorption into a non-volatile liquid and converting it into a useful bulk chemical, that is, HNO3....

  16. Effectiveness of liquid organic-nitrogen fertilizer in enhancing ...

    African Journals Online (AJOL)

    The ever increasing price of nitrogenous (N) fertilizers coupled with the deleterious effects of imbalanced N fertilizers on the environment necessitates the enhancement of N use efficiency of plants. The objectives of this study were to: (1) Evaluate the uptake of selected nutrients due to application of liquid organic-N ...

  17. Effect of liquid nitrogen storage time on the survival and ...

    African Journals Online (AJOL)

    Investigations were undertaken on the effect of liquid nitrogen (LN) storage time on survival and regeneration of somatic embryos of cocoa (Theobroma cacao l.). Somatic embryos from different cocoa genotypes (AMAZ 3-2, AMAZ 10-1, AMAZ 12, SIAL 93, and IMC 14) at 15.45% moisture content were cryopreserved in LN ...

  18. Isolating silkworm genomic DNA without liquid nitrogen suitable for ...

    African Journals Online (AJOL)

    Genomic DNA was isolated from posterior silk gland of silkworms, Antheraea assama. Absolute alcohol was used as tissue fixing solution instead of grinding in liquid nitrogen, which yielded high molecular weight DNA (>40 kb). Samples yielded similar amount of DNA when fixed in absolute alcohol (400 μmg/g of silk gland ...

  19. The investigation of rf-squids at liquid nitrogen temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Polushkin, V N; Vasiliev, B V [Joint Inst. for Nuclear Research, Dubna (USSR)

    1989-12-01

    One- and two-hole YBCO ceramic rf-squids operating at liquid nitrogen temperatures have been developed. The main squid parameters: self-inductance, white noise level and magnetic flux resolution were measured. The directly measured external field sensitivity for one-hole squid was at the level of 100 fT/{radical}Hz. (orig.).

  20. Liquid Nitrogen Dewar Loading at KSC for STS-71 Flight

    Science.gov (United States)

    1995-01-01

    Liquid nitrogen dewar loading at Kennedy Space Center for STS-71 flight with Stan Koszelak (right), University of California at Riverside, adn Tamara Chinareva (left), Russian Spacecraft Coporation-Energia. The picture shows Koszelak removing the insert from the transportation dewar.

  1. A high Tc superconducting liquid nitrogen level sensor

    International Nuclear Information System (INIS)

    Jin, J. X.; Liu, H. K.; Dou, S. X.; Grantham, C.; Beer, J.

    1996-01-01

    Full text: The dramatic resistance change in the superconducting-normal transition temperature range enables a high T c superconductor to be considered for designing a liquid nitrogen level sensor. A (Bi,Pb) 2 Sr 2 Ca 2 Cu 3 O 10+x Ag clad superconducting wire is selected and tested as a continuous liquid nitrogen level sensor to investigate the possibility for this application. The (Bi,Pb) 2 Sr 2 Ca 2 Cu 3 O 10+x Ag clad superconducting wire has approximately 110 K critical temperature, with more flexible and stable properties compared with bulk shape ceramic high T c superconductors. The voltage drops across the sensor are tested with different immersion lengths in liquid nitrogen. The accuracy of the HTS sensor is analysed with its dR/dT in the superconducting-normal transition range. The voltage signal is sensitive to liquid nitrogen level change, and this signal can be optimized by controlling the transport current. The problems of the Ag clad superconductor are that the Ag sheath thermal conductivity is very high, and the sensor normal resistance is low. These are the main disadvantages for using such a wire as a continuous level sensor. However, a satisfactory accuracy can be achieved by control of the transport current. A different configuration of the wire sensor is also designed to avoid this thermal influence

  2. Electrically and Thermally Insulated Joint for Liquid Nitrogen Transfer

    DEFF Research Database (Denmark)

    Rasmussen, Carsten; Jensen, Kim Høj; Holbøll, Joachim T.

    1999-01-01

    A prototype of a superconducting cable is currently under construction. The cable conductor is cooled by liquid nitrogen in order to obtain superconductivity. The peripheral cooling circuit is kept at ground potential. This requires a joint which insulates both electrically and thermally...

  3. Polystyrene cryostat facilitates testing tensile specimens under liquid nitrogen

    Science.gov (United States)

    Shogan, R. P.; Skalka, R. J.

    1967-01-01

    Lightweight cryostat made of expanded polystyrene reduces eccentricity in a tensile system being tested under liquid nitrogen. The cryostat is attached directly to the tensile system by a special seal, reducing misalignment effects due to cryostat weight, and facilitates viewing and loading of the specimens.

  4. The Effect of Liquid Nitrogen on Bone Graft Survival.

    Science.gov (United States)

    Sirinoglu, Hakan; Çilingir, Özlem Tuğçe; Çelebiler, Ozhan; Ercan, Feriha; Numanoglu, Ayhan

    2015-08-01

    Liquid nitrogen is used in medicine for cancer treatment and tissue preservation; however, bone viability after its application is controversial. This study aims to evaluate both the tissue viability and the clinical and histopathologic findings following liquid nitrogen application with different thawing techniques in rats. Mandibular bone grafts were taken from 45 Wistar rats and freezed in liquid nitrogen for 20 minutes. In the rapid-thawing technique (Rapid Thawing-1, Rapid Thawing-2), the grafts were held for 20 minutes in room temperature; in the slow-thawing technique (Slow Thawing-1, Slow Thawing-2), 20 minutes in -20°C, 20 minutes in +4°C, and 20 minutes in room temperature, respectively. In Rapid Thawing-2 and Slow Thawing-2 groups, autografts were implanted to their origin for 3 weeks and bone staining with India ink was performed and samples taken for histologic examination. The amount of cells and blood vessels and the density of bone canaliculi were significantly reduced in Rapid Thawing-1 and Slow Thawing-1 groups comparing to the Control group. However, the reduction rate was more significant in the Slow Thawing-1 group. Histomorphometric evaluation of the healing autografts after 3 weeks revealed that the decreased amounts of canaliculi were not changed in Slow Thawing-2 group. The study results demonstrated that bone tissue survives after liquid nitrogen treatment regardless of the performed thawing technique; however, slow thawing causes more tissue damage and metabolism impairment. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  5. Liquid nitrogen cryotherapy for conjunctival lymphangiectasia: a case series.

    Science.gov (United States)

    Fraunfelder, Frederick W

    2009-12-01

    To report a case series of conjunctival lymphangiectasia treated with liquid nitrogen cryotherapy. A 1.5-mm Brymill cryoprobe was applied in a double freeze-thaw method after an incisional biopsy of a portion of the conjunctiva in patients with conjunctival lymphangiectasia. Freeze times were 1 to 2 seconds with thawing of 5 to 10 seconds between treatments. Patients were reexamined at 1 day, 2 weeks, 3 months, 6 months, and yearly following cryotherapy. Five eyes of 4 patients (3 male and 1 female) with biopsy-proven conjunctival lymphangiectasia underwent liquid nitrogen cryotherapy. The average patient age was 53 years. Ocular examination revealed large lymphatic vessels that were translucent and without conjunctival injection. Subjective symptoms included epiphora, ocular irritation, eye redness, and occasional blurred vision. After treatment with liquid nitrogen cryotherapy, the patients' symptoms and signs resolved within 2 weeks. Lymphangiectasia recurred twice in one patient, at 1 and 3 years postoperatively. In another patient, lymphangiectasia recurred at 6 months. The average time to recurrence in these 3 eyes was 18 months. Average length of follow-up was 24.5 months for all subjects. Liquid nitrogen cryotherapy may be an effective surgical alternative in the treatment of conjunctival lymphangiectasia. Cryotherapy may need to be repeated in some instances.

  6. Liquid-vapour surface sensors for liquid nitrogen and hydrogen

    Science.gov (United States)

    Siegwarth, J. D.; Voth, R. O.; Snyder, S. M.

    1992-01-01

    The present paper identifies devices to serve as liquid-vapor detectors in zero gravity. The testing in LH2 was done in a sealed glass Dewar system to eliminate any chance of mixing H2 and air. Most of the tests were performed with the leads to the sensor horizontal. Some results of rapid cycle testing of LVDG in LH2 are presented. Findings of rapid-cycle testing of LVDG in LH2 are discussed. The sensor crossed the liquid surface when the position sensor registered 1.9 V, which occurred at about 0.4075 s. The delay time was about 1.5 ms. From the estimated slope of the position sensor curve at 1.9 V, the velocity of the sensor through the liquid surface is over 3 m/s. Results of tests of optical sensors are presented as well.

  7. Liquid nitrogen - water interaction experiments for fusion reactor accident scenarios

    International Nuclear Information System (INIS)

    Duckworth, R.; Murphy, J.; Pfotenhauer, J.; Corradini, M.

    2001-01-01

    With the implementation of superconducting magnets in fusion reactors, the possibility exists for the interaction between water and cryogenic systems. The interaction between liquid nitrogen and water was investigated experimentally and numerically. The rate of pressurization and peak pressure were found to be driven thermodynamically by the expansion of the water and the boil-off of the liquid nitrogen and did not have a vapor explosion nature. Since the peak pressure was small in comparison to previous work with stratified geometries, the role of the geometry of the interacting fluids has been shown to be significant. Comparisons of the peak pressure and the rate of pressurization with respect to the ratio of the liquid nitrogen mass to water mass reveal no functional dependence as was observed in the liquid helium-water experiments. A simple thermodynamic model provides a fairly good description of the pressure rise data. From the data, the model will allow one to extract the interaction area of the water. As with previous liquid helium-water interaction experiments, more extensive investigation of the mass ratio and interaction geometry is needed to define boundaries between explosive and non-explosive conditions. (authors)

  8. Successful vitrification of bovine immature oocyte using liquid helium instead of liquid nitrogen as cryogenic liquid.

    Science.gov (United States)

    Yu, Xue-Li; Xu, Ya-Kun; Wu, Hua; Guo, Xian-Fei; Li, Xiao-Xia; Han, Wen-Xia; Li, Ying-Hua

    2016-04-01

    The objectives of this study were to compare the effectiveness of liquid helium (LHe) and liquid nitrogen (LN2) as cryogenic liquid for vitrification of bovine immature oocytes with open-pulled straw (OPS) system and determine the optimal cryoprotectant concentration of LHe vitrification. Cumulus oocyte complexes were divided into three groups, namely, untreated group (control), LN2 vitrified with OPS group, and LHe vitrified with OPS group. Oocyte survival was assessed by morphology, nuclear maturation, and developmental capability. Results indicated that the rates of normal morphology, maturation, cleavage, and blastocyst (89.3%, 52.8%, 42.7%, and 10.1%, respectively) in the LHe-vitrified group were all higher than those (79.3%, 43.4%, 34.1%, and 4.7%) in the LN2-vitrified group (P 0.05). The maturation rate of the EDS35 group (65.0%) was higher than those of the EDS30 (51.3%), EDS40 (50.1%), EDS45 (52.1%), and EDS50 groups (36.9%; P liquid for vitrification of bovine immature oocytes, and it is more efficient than LN2-vitrified oocytes in terms of blastocyst production. EDS35 was the optimal cryoprotectant agent combination for LHe vitrification in this study. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. Study on the effect of subcooling on vapor film collapse on high temperature particle surface

    International Nuclear Information System (INIS)

    Abe, Yutaka; Tochio, Daisuke; Yanagida, Hiroshi

    2000-01-01

    Thermal detonation model is proposed to describe vapor explosion. According to this model, vapor film on pre-mixed high temperature droplet surface is needed to be collapsed for the trigger of the vapor explosion. It is pointed out that the vapor film collapse behavior is significantly affected by the subcooling of low temperature liquid. However, the effect of subcooling on micro-mechanism of vapor film collapse behavior is not experimentally well identified. The objective of the present research is to experimentally investigate the effect of subcooling on micro-mechanism of film boiling collapse behavior. As the results, it is experimentally clarified that the vapor film collapse behavior in low subcooling condition is qualitatively different from the vapor film collapse behavior in high subcooling condition. In case of vapor film collapse by pressure pulse, homogeneous vapor generation occurred all over the surface of steel particle in low subcooling condition. On the other hand, heterogeneous vapor generation was observed for higher subcooling condition. In case of vapor film collapse spontaneously, fluctuation of the gas-liquid interface after quenching propagated from bottom to top of the steel particle heterogeneously in low subcooling condition. On the other hand, simultaneous vapor generation occurred for higher subcooling condition. And the time transient of pressure, particle surface temperature, water temperature and visual information were simultaneously measured in the vapor film collapse experiment by external pressure pulse. Film thickness was estimated by visual data processing technique with the pictures taken by the high-speed video camera. Temperature and heat flux at the vapor-liquid interface were estimated by solving the heat condition equation with the measured pressure, liquid temperature and vapor film thickness as boundary conditions. Movement of the vapor-liquid interface were estimated with the PIV technique with the visual observation

  10. Liquid nitrogen cooling for the compact ignition tokamak

    International Nuclear Information System (INIS)

    Fleming, R.B.; Martin, G.D.; Lyon, R.E.

    1989-01-01

    The Compact Ignition Tokamak (CIT), which is currently being designed, will have toroidal and poloidal magnetic field coils pre-cooled by liquid nitrogen to a temperature near 80 degree K prior to each plasma pulse. The purpose is to gain the advantage of lower copper resistivity at reduced temperature. To maintain this temperature, the field coils, vacuum vessel, and surrounding structure will be enclosed within a cryostat. During a full-power D-T pulse, nuclear and resistive heating will impart a heat load of 11.0 GJ to the coils, which will raise the temperature of certain areas of the coils to near room temperature. The cryogenic system will supply 60,000 kg (19,500 gallons) of liquid nitrogen to remove this heat within a 60-minute cool-down period between pulses. A primary design consideration is that the nitrogen gas within the cryostat during a pulse will be activated by neutrons, producing nitrogen-13, which has a half-life of 10 minutes. This gas cannot be released into the environment without a sufficient decay period. The coolant nitrogen will therefore be contained within a closed (primary) circuit, and will be condensed in a heat exchanger. Liquid nitrogen from the supply dewars will be evaporated on the other side of the exchanger (the secondary side), and released to the atmosphere via a roof vent. Other operating modes (standby operation and initial cool-down from room temperature) are described in the paper. A safety analysis indicates that the cryogenic system will meet all applicable environmental requirements. 1 ref., 1 fig., 1 tab

  11. Experimental study of nitrogen oxide absorption by a liquid nitrogen tetroxide flow

    Energy Technology Data Exchange (ETDEWEB)

    Verzhinskaya, A B; Saskovets, V V; Borovik, T F

    1984-01-01

    The system of N/sub 2/O/sub 4/ based coolant regeneration needs productive and efficient absorbers, providing effective production of nitrogen oxide, decreasing upon NPP operation at the expense of radiation-thermal decomposition. The experimental istallation flowsheet for studying the nitrogen oxide absorbtion by liquid nitrogen tetroxide is given. The experiments have been carried out in removable test sections, looked like helical tubes with internal steam-and-liquid mixture flow and external water cooling. Six test sections with variable geometry factors have been manufactured. The plotted results of the experiments are given as dependences of extraction level and mass transfer volumetric coefficients on the geometry factor, pressure and Froude number.

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

    International Nuclear Information System (INIS)

    Hu, Lin-Wen; Pan, Chin

    1995-01-01

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

  13. Corrosion of ferrous alloys in nitrogen contaminated liquid lithium

    International Nuclear Information System (INIS)

    Olson, D.L.; Bradley, W.L.

    1976-01-01

    Liquid lithium penetration of 304L stainless steel and Armco iron grain boundaries has been studied. The penetration kinetics for the 304L stainless steel was found to be diffusion controlled. The measured temperature dependent delay time has been associated with the initial formation of the corrosion product at the grain boundary. Nitrogen in the stainless steel or the liquid lithium has been found to accelerate the rate of attack without changing the apparent activation energy. Grain boundary grooving of Armco iron in liquid lithium indicates that the controlling mass transport is also through a corrosion product present as a surface film. Stresses as small as 12 MPa have been found to give rise to a fifty-fold increase in the rate of penetration of Armco iron by liquid lithium

  14. Removal of nitrogen compounds from Brazilian petroleum samples by oxidation followed by liquid-liquid extraction

    Energy Technology Data Exchange (ETDEWEB)

    Conceicao, L.; Pergher, S.B.C. [Universidade Regional Integrada do Alto Uruguai e das Misses (URI), Erechim, RS (Brazil). Dept. de Quimica], E-mail: pergher@uricer.edu.br; Oliveira, J.V. [Universidade Regional Integrada do Alto Uruguai e das Misses (URI), Erechim, RS (Brazil). Dept. de Engenharia dos Alimentos; Souza, W.F. [Petroleo Brasileiro S.A. (CENPES/PETROBRAS), Rio de Janeiro, RJ (Brazil). Centro de Pesquisas

    2009-10-15

    This work reports liquid-liquid extraction of nitrogen compounds from oxidized and non-oxidized Brazilian petroleum samples. The experiments were accomplished in a laboratory-scale liquid-liquid apparatus in the temperature range of 303 K-323 K, using methanol, n-methyl-2-pyrrolidone (NMP) and N,Ndimethylformamide (DMF), and their mixtures as extraction solvents, employing solvent to sample volume ratios of 1:2, 1:1 and 2:1, exploring up to three separation stages. Results show that an increase in temperature, solvent to oil ratio, and number of equilibrium stages greatly improves the nitrogen removal from the oxidized sample (from 2600 to 200 ppm). The employed oxidation scheme is thus demonstrated to be an essential and efficient step of sample preparation for the selective liquid-liquid removal of nitrogen compounds. It is shown that the use of mixtures of DMF and NMP as well their use as co-solvents with methanol did not prove to be useful for selective nitrogen extraction since great oil losses were observed in the final process. (author)

  15. Polymerization, shock cooling and ionization of liquid nitrogen

    International Nuclear Information System (INIS)

    Ross, M; Rogers, F

    2005-01-01

    The trajectory of thermodynamic states passed through by the nitrogen Hugoniot starting from the liquid and up to 10 6 GPa has been studied. An earlier report of cooling in the doubly shocked liquid, near 50 to 100 GPa and 7500 K, is revisited in light of the recent discovery of solid polymeric nitrogen. It is found that cooling occurs when the doubly shocked liquid is driven into a volume near the molecular to polymer transition and raising the possibility of a liquid-liquid phase transition (LLPT). By increasing the shock pressure and temperature by an order of magnitude, theoretical calculations predict thermal ionization of the L shell drives the compression maxima to 5-6 fold compression at 10 Mbar (T ∼ 3.5 10 5 K) and at 400 Mbar (T ∼ 2.3 10 6 K) from K shell ionization. Near a pressure of 10 6 GPa the K shell ionizes completely and the Hugoniot approaches the classical ideal gas compression fourfold limit

  16. Liquid Nitrogen (Oxygen Simulent) Thermodynamic Venting System Test Data Analysis

    Science.gov (United States)

    Hedayat, A.; Nelson, S. L.; Hastings, L. J.; Flachbart, R. H.; Tucker, S. P.

    2005-01-01

    In designing systems for the long-term storage of cryogens in low gravity space environments, one must consider the effects of thermal stratification on excessive tank pressure that will occur due to environmental heat leakage. During low gravity operations, a Thermodynamic Venting System (TVS) concept is expected to maintain tank pressure without propellant resettling. The TVS consists of a recirculation pump, Joule-Thomson (J-T) expansion valve, and a parallel flow concentric tube heat exchanger combined with a longitudinal spray bar. Using a small amount of liquid extracted by the pump and passing it though the J-T valve, then through the heat exchanger, the bulk liquid and ullage are cooled, resulting in lower tank pressure. A series of TVS tests were conducted at the Marshall Space Flight Center using liquid nitrogen as a liquid oxygen simulant. The tests were performed at fill levels of 90%, 50%, and 25% with gaseous nitrogen and helium pressurants, and with a tank pressure control band of 7 kPa. A transient one-dimensional model of the TVS is used to analyze the data. The code is comprised of four models for the heat exchanger, the spray manifold and injector tubes, the recirculation pump, and the tank. The TVS model predicted ullage pressure and temperature and bulk liquid saturation pressure and temperature are compared with data. Details of predictions and comparisons with test data regarding pressure rise and collapse rates will be presented in the final paper.

  17. Polymerization, shock cooling and ionization of liquid nitrogen

    Energy Technology Data Exchange (ETDEWEB)

    Ross, M; Rogers, F

    2005-07-21

    The trajectory of thermodynamic states passed through by the nitrogen Hugoniot starting from the liquid and up to 10{sup 6} GPa has been studied. An earlier report of cooling in the doubly shocked liquid, near 50 to 100 GPa and 7500 K, is revisited in light of the recent discovery of solid polymeric nitrogen. It is found that cooling occurs when the doubly shocked liquid is driven into a volume near the molecular to polymer transition and raising the possibility of a liquid-liquid phase transition (LLPT). By increasing the shock pressure and temperature by an order of magnitude, theoretical calculations predict thermal ionization of the L shell drives the compression maxima to 5-6 fold compression at 10 Mbar (T {approx} 3.5 10{sup 5} K) and at 400 Mbar (T {approx} 2.3 10{sup 6} K) from K shell ionization. Near a pressure of 10{sup 6} GPa the K shell ionizes completely and the Hugoniot approaches the classical ideal gas compression fourfold limit.

  18. A lethal cocktail: gastric perforation following liquid nitrogen ingestion.

    Science.gov (United States)

    Pollard, James Scott; Simpson, Joanne Elizabeth; Bukhari, Moatasiem Idris

    2013-01-07

    We report a case of gastric perforation in an 18-year-old girl as a result of ingesting an alcoholic drink containing liquid nitrogen. The drink was purchased in licensed premises. The extent of the injury necessitated total gastrectomy with Roux-en Y reconstruction. We review the literature, discuss the mechanism of injury and consider the implications for medical services. The authors believe this case is of educational interest to professionals working in emergency medicine, general surgery and public health fields. It raises awareness of a rare injury, but one that may be more commonly encountered because of developing social trends. It informs surgeons confronted with this type of injury that trauma to the gastrointestinal tract can be extensive and preoperative contact with oesophago-gastric colleagues is advisable. Public health bodies must be aware of, and monitor, the use of liquid nitrogen in this way and consider regulation to prevent further injuries.

  19. Liquid nitrogen enhancement of alpha particle tracks in a polycarbonate detector

    International Nuclear Information System (INIS)

    Pilione, L.J.

    1977-01-01

    Makrofol-E polycarbonate detectors were exposed to 1 to 3 MeV alpha particles and subsequently immersed in liquid nitrogen for various periods of time. The influence of the liquid nitrogen on the track recording properties of the detector has been found by measuring the track densities and diameters. Track densities increase with immersion time with a maximum gain of approximately 9% after 1200 min in liquid nitrogen. Track enhancement decreases with waiting time between the end of alpha particle exposure and the beginning of liquid nitrogen immersion. Track diameters decrease with time after passage of the particles and this process is accelerated by immersion in liquid nitrogen. (author)

  20. A liquid nitrogen cooled polyethylene moderator for the Harwell Linac

    International Nuclear Information System (INIS)

    Boland, B.C.; Hey, P.D.; Houzego, P.J.; Mack, B.; Mildner, D.F.R.; Sinclair, R.N.

    1978-09-01

    A 40 mm thick polyethylene block has been maintained at a temperature close to 80 K by using a liquid nitrogen cryostat, and used to moderate neutrons from pulsed source. The assembly has been tested with a dummy heat load of 400W. The cryostat and cooling system was installed on the Harwell 45 MeV electron linac, and enabled the production of sharper pulses in the thermal neutron energy range. The design, safety considerations and performance are described. (author)

  1. Acoustic velocity investigation and density calculation in liquid nitrogen tetroxide

    International Nuclear Information System (INIS)

    Belyaeva, O.V.; Nikolaev, V.A.; Timofeev, B.D.

    1979-01-01

    Acoustic velocity in liquid nitrogen tetroxide was investigated on an ultrasonic interferometer, which represents a tube with the 30x2.5 mm diameter, at the ends of which ultrasonic sensors are located. The sensors and the interferometer tube are fabricated of the Kh18N9T stainless steel. The calibration tests were carried out on twice-distilled water at the pressure from 1 to 80 bar in the operational range of temperatures from 283 to 360 K. The relative mean square error in experimental data on the acoustic velocity in liquid nitrogen tetroxide is 0.17%. The experimental data are described by the interpolation polynom in the investigated range of state parameters. On the basis of experimental data on the density of liquid nitrogen tetroxide near the saturation line and the experimental values of acoustic velocity, an interpolation equation is suggested to calculate the substance density under investigation in the range of 290-360 K from pressures corresponding to the saturation line, to 300 bar

  2. Liquid Nitrogen (Oxygen Simulant) Thermodynamic Vent System Test Data Analysis

    Science.gov (United States)

    Hedayat, A.; Nelson, S. L.; Hastings, L. J.; Flachbart, R. H.; Tucker, S. P.

    2005-01-01

    In designing systems for the long-term storage of cryogens in low-gravity (space) environments, one must consider the effects of thermal stratification on tank pressure that will occur due to environmental heat leaks. During low-gravity operations, a Thermodynamic Vent System (TVS) concept is expected to maintain tank pressure without propellant resettling. A series of TVS tests was conducted at NASA Marshall Space Flight Center (MSFC) using liquid nitrogen (LN2) as a liquid oxygen (LO2) simulant. The tests were performed at tank til1 levels of 90%, 50%, and 25%, and with a specified tank pressure control band. A transient one-dimensional TVS performance program is used to analyze and correlate the test data for all three fill levels. Predictions and comparisons of ullage pressure and temperature and bulk liquid saturation pressure and temperature with test data are presented.

  3. Kinetics of liquid lithium reaction with oxygen-nitrogen mixtures

    International Nuclear Information System (INIS)

    Gil, T.K.; Kazimi, M.S.

    1986-01-01

    A series of experiments have been conducted in order to characterize the kinetics of lithium chemical reaction with a mixture of oxygen and nitrogen. Three mixed gas compositions were used; 80% N 2 and 20% O 2 , 90% N 2 and 10% O 2 , and 95% N 2 and 5% O 2 . The reaction rate was obtained as a function of lithium temperature and the oxygen fraction. Liquid lithium temperature varied from 400 to 1100 0 C. By varying the composition, the degree of inhibition of the lithium-nitrogen reaction rate due to the presence of oxygen was observed. The results indicate that the lithium-nitrogen reaction rate depended on both the fraction of oxygen present and lithium temperature. The lithium nitride layer formed from the reaction also had a significant inhibition effect on the lithium-nitrogen reaction rate while the lithium-oxygen reaction rate was not as greatly hindered. LITFIRE, a computer code which simulates temperature and pressure history in a containment building following lithium spills, was modified by including (1) an improved model for the lithium-nitrogen reaction rate and (2) a model for the lithium-CO 2 reaction. LITFIRE was used to simulate HEDL's LC-2 and LA-5 experiments, and the predicted temperatures and pressures were in a reasonable agreement. Furthermore, LITFIRE was applied to a prototypical fusion reactor containment in order to simulate the consequences of a lithium spill accident. The result indicated that if nitrogen was used as containment building gas during the accident, the consequences of the accident would be less severe than those with air. The pressure rise in the building was found to be reduced by 50% and the maximum temperature of the combustion zone was limited to 900 0 C instead of 1200 0 C in the case of air

  4. Production of liquid nitrogen using liquefied natural gas as sole refrigerant

    International Nuclear Information System (INIS)

    Agrawal, R.; Ayres, C.L.

    1992-01-01

    This patent describes a process for the liquefaction of a nitrogen stream produced by a cryogenic air separation unit having at least one distillation column. It comprises compressing the nitrogen stream to a pressure of at least 350 psi in a multi-stage compressor wherein interstage cooling is provided by heat exchange against vaporizing liquefied natural gas; condensing the compressed nitrogen stream by heat exchange against vaporizing liquefied natural gas; reducing the pressure of the condensed, compressed nitrogen stream thereby producing a two phase nitrogen stream; phase separating the two phase nitrogen stream into a liquid nitrogen stream and a nitrogen vapor stream; and warming the nitrogen vapor stream to recover refrigeration

  5. The solubility of carbon in low-nitrogen liquid lithium

    International Nuclear Information System (INIS)

    Yonco, R.M.; Homa, M.I.

    1986-01-01

    The solubility of carbon in liquid lithium containing 0 C and compared with the solubility in lithium containing proportional 2600 wppm nitrogen in that same temperature range. A direct sampling method was employed in which filtered samples of the saturated solution were taken at randomly selected temperatures. The entire sample was analyzed for carbon by the acetylene evolution method. The analytical method was examined critically and it was found that (1) all of the carbon in solution, including carbon introduced as lithium cyanamide is detected and (2) ethylene and ethane must also be measured and included with the acetylene to get complete recovery of the carbon content of the sample. The solubility of carbon in low-nitrogen lithium can be expressed by the equations ln S=6.731-8617T -1 and log Ssup(*)=7.459-3740T -1 , where S is the mole percent Li 2 C 2 and Ssup(*) is in weight parts per million carbon. The presence of proportional 2600 wppm nitrogen does not affect the solubility of carbon in lithium at temperatures above proportional 350 0 C, but at lower temperatures it increased the solubility by as much as an order of magnitude compared to the solubility in low-nitrogen lithium. (orig.)

  6. Visualization of bubble behaviors in forced convective subcooled flow boiling

    International Nuclear Information System (INIS)

    Inaba, Noriaki; Matsuzaki, Mitsuo; Kikura, Hiroshige; Aritomi, Masanori; Komeno, Toshihiro

    2007-01-01

    Condensation characteristics of vapor bubble after the departure from a heated section in forced convective subcooled flow boiling were studied visually by using a high speed camera. The purpose of the present study was to measure two-phase flow parameters in subcooled flow boiling. These two-phase flow parameters are void fraction, interfacial area concentration and Sauter mean diameter, which express bubble interface behaviors. The experimental set-up was designed to measure the two-phase flow parameters necessary for developing composite equations for the two fluid models in subcooled flow boiling. In the present experiments, the mass flux, liquid subcooling and the heater were varied within 100-1000kg/m 2 s, 2-10K and 100-300kW/m 2 respectively. Under these experimental conditions, the bubble images were obtained by a high-speed camera, and analyzed paying attention to the condensation of vapor bubbles. These two-phase parameters were obtained by the experimental data, such as the bubble parameter, the bubble volume and the bubble surface. In the calculation process of the two phase flow parameters, it was confirmed that these parameters are related to the void fraction. (author)

  7. Extending cavitation models to subcooled and superheated nozzle flow

    International Nuclear Information System (INIS)

    Schmidt, D.P.; Corradini, M.L.

    1997-01-01

    Existing models for cavitating flow are extended to apply to discharge of hot liquid through nozzles. Two types of models are considered: an analytical model and a two-dimensional numerical model. The analytical model of cavitating nozzle flow is reviewed and shown to apply to critical nozzle flow where the liquid is subcooled with respect to the downstream conditions. In this model the liquid and vapor are assumed to be in thermodynamic equilibrium. The success of this analytical model suggests that hydrodynamic effects dominate the subcooled nozzle flow. For more detailed predictions an existing multi-dimensional cavitation model based on hydrodynamic non-equilibrium is modified to apply to discharge of hot liquid. Non-equilibrium rate data from experimental measurements are used to close the equations. The governing equations are solved numerically in time and in two spatial dimensions on a boundary fitted grid. Results are shown for flow through sharp nozzles, and the coefficient of discharge is found to agree with experimental measurements for both subcooled and flashing fluid. (author)

  8. Liquid nitrogen cooling considerations of the compact ignition tokamak

    International Nuclear Information System (INIS)

    Dabiri, A.E.

    1986-01-01

    An analytical procedure was developed to estimate the cooldown time between pulses of the Compact Ignition Tokamak (CIT) utilizing liquid nitrogen. Fairly good agreement was obtained between the analysis results and those measured in the early fusion experimental devices. The cooldown time between pulses in the CIT is controlled by the energy disposition in the inner leg of the TF coil. A cooldown time of less than one hour is feasible for the CIT if fins are used in the cooling channels. An R and D experimental program is proposed to determine the actual cooldown time between pulses since this would be considered an issue in the conceptual design of the CIT

  9. Automatic dispensing of liquid nitrogen in submilliliter doses

    Science.gov (United States)

    Milner, C. J.

    1984-10-01

    Well-controlled doses of 0.2 to 0.5 ml of liquid nitrogen are delivered, on electrical signal (not more than once per 5 s), as fills of a miniature bucket raised by an automatic hoist. The bucket is lifted, brimming, from the storage flask and then moved sideways until over the receiver. At this point, a steel ball, which has been resting in and sealing a drain hole in the bucket, is lifted from its seat by a magnet fixed alongside the (now descending) bucket. Design features are outlined: some alternative designs, valving liquid through a short drain tube fixed in the storage flask, are briefly reviewed. In tests the device delivered 74 g (approx. 260 doses) during 63 min, the loss by evaporation meanwhile being 11 g from the bucket, implying a transfer efficiency of 87%. An indirect measure indicated the dose sizes as 354±10 μl approximately.

  10. Downward transfer of a sub-cooled cryoliquid

    CERN Document Server

    Wertelaers, P

    2016-01-01

    An alternative is proposed to the traditional transfer of a cryo fluid in gaseous -- and warm -- form, a method of low productivity and high energy cost. In order to prevent the much-feared geysering, focus is on sub-cooling of the liquid, and the safe maintaining of such state all along the journey. A cryogenic transfer line of simplest construction is proposed, and the difficulties with such line extending over a transfer depth of the order of the kilometre, are discussed.

  11. Thermodynamic processes associated with frostbite in the handling of liquid nitrogen

    Science.gov (United States)

    Johnson, W. L.; Cook, C. R.

    2014-01-01

    It is often taught that exposure to liquid nitrogen will cause frostbite or more severe damage to exposed skin tissue. However, it is also demonstrated that a full hand can be briefly immersed in liquid nitrogen without damage. To better understand and possibly visualize the effects of human tissue exposure to liquid nitrogen, a series of tests were conducted using simulated hands and arms composed of molded gelatin forms. The simulated hands and arms were immersed, sprayed, or splashed with liquid nitrogen both with and without state of the art personal protective equipment. Thermocouples were located within the test articles to allow for thermal mapping during the freezing process. The study is aimed to help understand frostbite hazards and the time constants involved with the handling of liquid nitrogen to improve future safety protocols for the safe handling of cryogenic fluids. Results of the testing also show the limits to handling liquid nitrogen while using various means of protection.

  12. Thermodynamic processes associated with frostbite in the handling of liquid nitrogen

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, W. L. [Cryogenics Test Laboratory, NASA Kennedy Space Center, Kennedy Space Center, FL, 32899 (United States); Cook, C. R. [Dept. Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL, 32611 (United States)

    2014-01-29

    It is often taught that exposure to liquid nitrogen will cause frostbite or more severe damage to exposed skin tissue. However, it is also demonstrated that a full hand can be briefly immersed in liquid nitrogen without damage. To better understand and possibly visualize the effects of human tissue exposure to liquid nitrogen, a series of tests were conducted using simulated hands and arms composed of molded gelatin forms. The simulated hands and arms were immersed, sprayed, or splashed with liquid nitrogen both with and without state of the art personal protective equipment. Thermocouples were located within the test articles to allow for thermal mapping during the freezing process. The study is aimed to help understand frostbite hazards and the time constants involved with the handling of liquid nitrogen to improve future safety protocols for the safe handling of cryogenic fluids. Results of the testing also show the limits to handling liquid nitrogen while using various means of protection.

  13. Thermodynamic processes associated with frostbite in the handling of liquid nitrogen

    International Nuclear Information System (INIS)

    Johnson, W. L.; Cook, C. R.

    2014-01-01

    It is often taught that exposure to liquid nitrogen will cause frostbite or more severe damage to exposed skin tissue. However, it is also demonstrated that a full hand can be briefly immersed in liquid nitrogen without damage. To better understand and possibly visualize the effects of human tissue exposure to liquid nitrogen, a series of tests were conducted using simulated hands and arms composed of molded gelatin forms. The simulated hands and arms were immersed, sprayed, or splashed with liquid nitrogen both with and without state of the art personal protective equipment. Thermocouples were located within the test articles to allow for thermal mapping during the freezing process. The study is aimed to help understand frostbite hazards and the time constants involved with the handling of liquid nitrogen to improve future safety protocols for the safe handling of cryogenic fluids. Results of the testing also show the limits to handling liquid nitrogen while using various means of protection

  14. Trial manufacture of liquid nitrogen cooling High Temperature Superconductivity Motor

    International Nuclear Information System (INIS)

    Sugimoto, H; Nishikawa, T; Tsuda, T; Hondou, Y; Akita, Y; Takeda, T; Okazaki, T; Ohashi, S; Yoshida, Y

    2006-01-01

    We present a new high temperature superconductivity (HTS) synchronous motor using the liquid nitrogen as the refrigerant in this paper. This motor is designed to be used as the propulsion motor in ship. Because we use the liquid nitrogen as the refrigerant, it is possible to simplify the cooling equipments in the motor. And in our design, we apply the axial flux type of motor to simplify the cryostat of the HTS wires used to make the field coils. Here, the fields using the bismuth HTS wire for the HTS coils are fixed. Moreover, the cores used in the fields are separated from cryostat, and the armature applies the core-less structure. According to various the electromagnetic field analysis results, the new motor was designed and produced. The diameter of the motor is 650mm, and the width of the motor is 360mm. The motor's rated output is 8.8kW at 100rpm, while the overload output is 44kW, and the maximum efficiency is 97.7%. Also, in order to further miniaturize the motor, other magnetic field analysis have been done when the high-current-density type HTS wire was used and the permendur was used instead of magnetic steel plates. In this case, the motor's rated output is 12kW, and the overload output is 60kW

  15. Contamination of liquid oxygen by pressurized gaseous nitrogen

    Science.gov (United States)

    Zuckerwar, Allan J.; King, Tracy K.; Ngo, Kim Chi

    1989-01-01

    The penetration of pressurized gaseous nitrogen (GN2) into liquid oxygen (LOX) was investigated experimentally in the 7-inch High Temperature Tunnel, the pilot tunnel for the 8-foot High Temperature Tunnel (8'HTT) at Langley Research Center. A preliminary test using a nuclear monitor revealed the extent of the liquid nitrogen (LN2) build-up at the LOX interface as a function of GN2 pressure. Then an adaptation of the differential flash vaporization technique was used to determine the binary diffusivity of the LOX-LN2 system at a temperature of 90.2 K. The measured value D equals 0.000086 sq cm/s + or - 25 percent together with two prior measurements at lower temperatures revealed an excellent fit to the Arrhenius equation, yielding a pre-exponential factor D sub 0 equals 0.0452 sq cm/s and an activation enthalpy H equals 1.08 kcal/mol. At a pressure of 1700 psi and holding time of 15 min, the penetration of LN2 into LOX (to a 1 percent contamination level) was found to be 0.9 cm, indicating but minimal impact upon 8'HTT operations.

  16. High Energy Cutting and Stripping Utilizing Liquid Nitrogen

    Science.gov (United States)

    Hume, Howard; Noah, Donald E.; Hayes, Paul W.

    2005-01-01

    The Aerospace Industry has endeavored for decades to develop hybrid materials that withstand the rigors of mechanized flight both within our atmosphere and beyond. The development of these high performance materials has led to the need for environmentally friendly technologies for material re-work and removal. The NitroJet(TM) is a fluid jet technology that represents an evolution of the widely used, large-scale water jet fluid jet technology. It involves the amalgamation of fluid jet technology and cryogenics technology to create a new capability that is applicable where water jet or abrasive jet (water jet plus entrained abrasive) are not suitable or acceptable because of technical constraints such as process or materials compatibility, environmental concerns and aesthetic or legal requirements. The NitroJet(TM) uses ultra high-pressure nitrogen to cut materials, strip numerous types of coatings such as paint or powder coating, clean surfaces and profile metals. Liquid nitrogen (LN2) is used as the feed stream and is pressurized in two stages. The first stage pressurizes sub cooled LN2 to an intermediate pressure of between 15,000 and 20,000 psi at which point the temperature of the LN2 is about -250 F. The discharge from this stage is then introduced as feed to a dual intensifier system, which boosts the pressure from 15,000 - 20,000 psi up to the maximum operating pressure of 55,000 psi. A temperature of about -220 F is achieved at which point the nitrogen is supercritical. In this condition the nitrogen cuts, strips and abrades much like ultra high-pressure water would but without any residual liquid to collect, remove or be contaminated. Once the nitrogen has performed its function it harmlessly flashes back into the atmosphere as pure nitrogen gas. The system uses heat exchangers to control and modify the temperature of the various intake and discharge nitrogen streams. Since the system is hydraulically operated, discharge pressures can be easily varied over

  17. Measurement of wetted area fraction in subcooled pool boiling of water using infrared thermography

    International Nuclear Information System (INIS)

    Kim, Hyungdae; Park, Youngjae; Buongiorno, Jacopo

    2013-01-01

    The wetted area fraction in subcooled pool boiling of water at atmospheric pressure is measured using the DEPIcT (DEtection of Phase by Infrared Thermography) technique. DEPIcT exploits the contrast in infrared (IR) light emissions between wet and dry areas on the surface of an IR-transparent heater to visualize the instantaneous distribution of the liquid and gas phases in contact with the heater surface. In this paper time-averaged wetted area fraction data in nucleate boiling are reported as functions of heat flux (from 30% up to 100% of the Critical Heat Flux) and subcooling (ΔT sub = 0, 5, 10, 30 and 50 °C). The results show that the wetted area fraction monotonically decreases with increasing heat flux and increases with increasing subcooling: both trends are expected. The range of time-averaged wetted area fractions is from 90%, at low heat flux and high subcooling, to 50% at high heat flux (right before CHF) and low subcooling. It is also shown that the dry areas are periodically rewetted by liquid sloshing on the surface at any subcooling and heat flux; however, the dry areas expand irreversibly at CHF

  18. Prediction of vapour-liquid and vapour-liquid-liquid equilibria of nitrogen-hydrocarbon mixtures used in J-T refrigerators

    Science.gov (United States)

    Narayanan, Vineed; Venkatarathnam, G.

    2018-03-01

    Nitrogen-hydrocarbon mixtures are widely used as refrigerants in J-T refrigerators operating with mixtures, as well as in natural gas liquefiers. The Peng-Robinson equation of state has traditionally been used to simulate the above cryogenic process. Multi parameter Helmholtz energy equations are now preferred for determining the properties of natural gas. They have, however, been used only to predict vapour-liquid equilibria, and not vapour-liquid-liquid equilibria that can occur in mixtures used in cryogenic mixed refrigerant processes. In this paper the vapour-liquid equilibrium of binary mixtures of nitrogen-methane, nitrogen-ethane, nitrogen-propane, nitrogen-isobutane and three component mixtures of nitrogen-methane-ethane and nitrogen-methane-propane have been studied with the Peng-Robinson and the Helmholtz energy equations of state of NIST REFPROP and compared with experimental data available in the literature.

  19. Changes of enthalpy slope in subcooled flow boiling

    Energy Technology Data Exchange (ETDEWEB)

    Collado, Francisco J.; Monne, Carlos [Universidad de Zaragoza-CPS, Departamento de Ingenieria Mecanica-Motores Termicos, Zaragoza (Spain); Pascau, Antonio [Universidad de Zaragoza-CPS, Departamento de Ciencia de los Materiales y Fluidos-Mecanica de Fluidos, Zaragoza (Spain)

    2006-03-01

    Void fraction data in subcooled flow boiling of water at low pressure measured by General Electric in the 1960s are analyzed following the classical model of Griffith et al. (in Proceedings of ASME-AIChE heat transfer conference, 58-HT-19, 1958). In addition, a new proposal for analyzing one-dimensional steady flow boiling is used. This is based on the physical fact that if the two phases have different velocities, they cannot cover the same distance - the control volume length - in the same time. So a slight modification of the heat balance is suggested, i.e., the explicit inclusion of the vapor-liquid velocity ratio or slip ratio as scaling time factor between the phases, which is successfully checked against the data. Finally, the prediction of void fraction using correlations of the net rate of change of vapor enthalpy in the fully developed regime of subcooled flow boiling is explored. (orig.)

  20. Properties of concrete mixed with sand frozen by liquid nitrogen

    International Nuclear Information System (INIS)

    Negami, Yoshiaki; Kurita, Morio; Kuwahara, Takashi; Goto, Sadao.

    1990-01-01

    This paper presents a new precooling method which reduces the temperature of mixed concrete by mixing it with sand frozen by liquid nitrogen. The authors tried to clarify the properties of both the frozen sand and the concrete mixed with the frozen sand. The results of a series of experimental studies indicate that the temperature of mixed concrete can be reduced about 25degC, which is a larger reduction quantity than that achieved by conventional precooling methods; and that this method contributes to improvement of the consistency and the compressive strength of the concrete. Furthermore, the advantageous effect of this precooling method is confirmed from the results of laboratory tests using massive concrete members. (author)

  1. Liquid Nitrogen Temperature Operation of a Switching Power Converter

    Science.gov (United States)

    Ray, Biswajit; Gerber, Scott S.; Patterson, Richard L.; Myers, Ira T.

    1995-01-01

    The performance of a 42/28 V, 175 W, 50 kHz pulse-width modulated buck dc/dc switching power converter at liquid nitrogen temperature (LNT) is compared with room temperature operation. The power circuit as well as the control circuit of the converter, designed with commercially available components, were operated at LNT and resulted in a slight improvement in converter efficiency. The improvement in power MOSFET operation was offset by deteriorating performance of the output diode rectifier at LNT. Performance of the converter could be further improved at low temperatures by using only power MOSFET's as switches. The use of a resonant topology will further improve the circuit performance by reducing the switching noise and loss.

  2. Heat and mass transfer of liquid nitrogen in coal porous media

    Science.gov (United States)

    Lang, Lu; Chengyun, Xin; Xinyu, Liu

    2018-04-01

    Liquid nitrogen has been working as an important medium in fire extinguishing and prevention, due to its efficiency in oxygen exclusion and heat removal. Such a technique is especially crucial for coal industry in China. We built a tunnel model with a temperature monitor system (with 36 thermocouples installed) to experimentally study heat and mass transfer of liquid nitrogen in non-homogeneous coal porous media (CPM), and expected to optimize parameters of liquid nitrogen injection in engineering applications. Results indicate that injection location and amount of liquid nitrogen, together with air leakage, significantly affect temperature distribution in CPM, and non-equilibrium heat inside and outside of coal particles. The injection position of liquid nitrogen determines locations of the lowest CPM temperature and liquid nitrogen residual. In the deeper coal bed, coal particles take longer time to reach thermal equilibrium between their surface and inside. Air leakage accelerates temperature increase at the bottom of the coal bed, which is a major reason leading to fire prevention inefficiency. Measurement fluctuation of CPM temperature may be caused by incomplete contact of coal particles with liquid nitrogen flowing in the coal bed. Moreover, the secondary temperature drop (STD) happens and grows with the more injection of liquid nitrogen, and the STD phenomenon is explained through temperature distributions at different locations.

  3. Advantages of liquid nitrogen freezing of Penaeus monodon over conventional plate freezing

    OpenAIRE

    Chakrabarti, R.; Chaudhury, D.R.

    1987-01-01

    Liquid nitrogen frozen products are biochemically and organoleptically superior to conventional plate frozen products but beneficial effect of liquid nitrogen freezing over conventional plate freezing can exist only up to 59 days at a commercial storage temperature of -18°C.

  4. Effect of liquid nitrogen storage on seed germination of 51 tree species

    Science.gov (United States)

    Jill R. Barbour; Bernard R. Parresol

    2003-01-01

    Two liquid nitrogen storage experiments were performed on 51 tree species. In experiment 1, seeds of 9western tree species were placed in a liquid nitrogen tank for 3 time periods: 24 hours, 4 weeks, and 222 days. A corresponding control sample accompanied each treatment. For three species,Calocedrus decurrens, Pinus jefferyi, and ...

  5. Surface roughness effects on onset of nucleate boiling and net vapor generation point in subcooled flow boiling

    International Nuclear Information System (INIS)

    Ohtake, Hiroyasu; Wada, Noriyoshi; Koizumi, Yasuo

    2003-01-01

    The ability to predict void formation and void fraction in subcooled flow boiling is of importance to the nuclear reactor technology because the presence of voids affects the steady state and transient response of a reactor. The onset of nucleate boiling and the point of net vapor generation on subcooled flow boiling, focusing on surface roughness, liquid subcooling and liquid velocity were investigated experimentally and analytically. Experiments were conducted using a copper thin-film and subcooled water in a range of the liquid velocity from 0.27 to 4.6 m/s at 0.10MPa; the liquid subcoolings were 20, 30 and 40K, respectively. The surface roughness on the test heater was observed by SEM. Experimental results showed that temperatures at the onset nucleate boiling increased with increasing the liquid subcoolings or the liquid velocities. The trend of increase in the temperature at the ONB was in good agreement with the present analytical result based on the stability theory of preexisting nuclei. The measured results for the net vapor generation point agreed well with the results of correlation by Saha and Zuber in the range of the present experiments. The temperature at the ONB decreased with an increasing size of surface roughness, while the NVG-point was independent on the surface roughness. The dependence on the ONB temperature of the roughness size was also represented well by the present analytical model

  6. Homogeneous nucleation in liquid nitrogen at negative pressures

    Energy Technology Data Exchange (ETDEWEB)

    Baidakov, V. G., E-mail: baidakov@itp.uran.ru; Vinogradov, V. E.; Pavlov, P. A. [Russian Academy of Sciences, Institute of Thermal Physics, Ural Branch (Russian Federation)

    2016-10-15

    The kinetics of spontaneous cavitation in liquid nitrogen at positive and negative pressures has been studied in a tension wave formed by a compression pulse reflected from the liquid–vapor interface on a thin platinum wire heated by a current pulse. The limiting tensile stresses (Δp = p{sub s}–p, where p{sub s} is the saturation pressure), the corresponding bubble nucleation frequencies J (10{sup 20}–10{sup 22} s{sup –1} m{sup –3}), and temperature induced nucleation frequency growth rate G{sub T} = dlnJ/dT have been experimentally determined. At T = 90 K, the limiting tensile stress was Δp = 8.3 MPa, which was 4.9 MPa lower than the value corresponding to the boundary of thermodynamic stability of the liquid phase (spinodal). The measurement results were compared to classical (homogeneous) nucleation theory (CNT) with and without neglect of the dependence of the surface tension of critical bubbles on their dimensions. In the latter case, the properties of new phase nuclei were described in terms of the Van der Waals theory of capillarity. The experimental data agree well with the CNT theory when it takes into account the “size effect.”.

  7. Critical flashing flows in nozzles with subcooled inlet conditions

    International Nuclear Information System (INIS)

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

    1983-01-01

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

  8. A study of forced convective subcooled flow boiling

    International Nuclear Information System (INIS)

    Serizawa, Akimi; Kenning, D.B.R.

    1979-01-01

    Based on a simple nucleation model, parameter survey technique is used to derive a predictive correlation for boiling initiation under forced convection. Results are expressed by a semi-empirical equation which considers effects of the flow turbulence on interfacial heat transfer coefficient for evaporation and condensation of vapour bubbles during their growth. This correlation agrees within +-25% with a variety of experimental water data presently available. The bubble departure diameter and the subcooling-dependence of active nucleation sites were examined, using experimental data available. Results are expressed by empirical equations. Finally, an analytical model is presented to predict conditions for the point of net vapour generation. The model is based on the formation and growth of a bubble boundary layer adjacent to the heated wall. It is shown that the point of net vapour generation is determined by the liquid subcooling at the boiling initiation and the subcooling-dependences of bubble departure diameter and bubble flux. The result implies that the bubble ejection from bubble layer is a possible mechanism for the significant void increase even at high velocities. (author)

  9. Pulsating-gliding transition in the dynamics of levitating liquid nitrogen droplets

    Energy Technology Data Exchange (ETDEWEB)

    Snezhko, Alexey; Aranson, Igor S [Materials Science Division, Argonne National Laboratory, 9700 S Cass Avenue, Argonne, IL 60439 (United States); Jacob, Eshel Ben [School of Physics and Astronomy, 69978 Tel Aviv University, Tel Aviv (Israel)], E-mail: aranson@msd.anl.gov

    2008-04-15

    Hot surfaces can cause levitation of small liquid droplets if the temperature is kept above the Leidenfrost point (220 {sup 0}C for water) due to the pressure formed because of rapid evaporation. Here, we demonstrate a new class of pulsating-gliding dynamic transitions in a special setting of the Leidenfrost effect at room temperatures and above a viscous fluid for droplets of liquid nitrogen. A whole range of highly dynamic patterns unfolds when droplets of liquid nitrogen are poured on the surface of another, more viscous liquid at room temperature. We also discovered that the levitating droplets induce vortex motion in the supporting viscous liquid. Depending on the viscosity of the supporting liquid, the nitrogen droplets either adopt an oscillating (pulsating) star-like shape with different azimuthal symmetries (from 2-9 petals) or glide on the surface with random trajectories. Thus, by varying the viscosity of the supporting liquid, we achieve controlled morphology and dynamics of Leidenfrost droplets.

  10. Pulsating-gliding transition in the dynamics of levitating liquid nitrogen droplets

    International Nuclear Information System (INIS)

    Snezhko, Alexey; Aranson, Igor S; Jacob, Eshel Ben

    2008-01-01

    Hot surfaces can cause levitation of small liquid droplets if the temperature is kept above the Leidenfrost point (220 0 C for water) due to the pressure formed because of rapid evaporation. Here, we demonstrate a new class of pulsating-gliding dynamic transitions in a special setting of the Leidenfrost effect at room temperatures and above a viscous fluid for droplets of liquid nitrogen. A whole range of highly dynamic patterns unfolds when droplets of liquid nitrogen are poured on the surface of another, more viscous liquid at room temperature. We also discovered that the levitating droplets induce vortex motion in the supporting viscous liquid. Depending on the viscosity of the supporting liquid, the nitrogen droplets either adopt an oscillating (pulsating) star-like shape with different azimuthal symmetries (from 2-9 petals) or glide on the surface with random trajectories. Thus, by varying the viscosity of the supporting liquid, we achieve controlled morphology and dynamics of Leidenfrost droplets

  11. Conjugate heat transfer effects on wall bubble nucleation in subcooled flashing flows

    International Nuclear Information System (INIS)

    Peterson, P.F.; Hijikata, K.

    1990-01-01

    A variety of models have been proposed to explain observations that large liquid superheat is required to initiate nucleation in flashing flows of subcooled liquids in nozzles, cracks and pipes. In such flows an abrupt change in the fluid temperature occurs downstream of the nucleating cavities. This paper examines the subcooling of the nucleating cavities due to conjugate heat transfer to the cold downstream fluid. This examination suggests a mechanism limiting the maximum active cavity size. Simple analysis shows that, of the total superheat required to initiate flashing, a substantial portion results from conjugate wall subcooling, which decreases the cavity vapor pressure. The specific case of flashing critical nozzle flow is examined in detail. Here boundary-layer laminarization due to the strong favorable pressure gradient aids the analysis of conjugate heat transfer

  12. Small-scale experimental study of vaporization flux of liquid nitrogen released on water.

    Science.gov (United States)

    Gopalaswami, Nirupama; Olewski, Tomasz; Véchot, Luc N; Mannan, M Sam

    2015-10-30

    A small-scale experimental study was conducted using liquid nitrogen to investigate the convective heat transfer behavior of cryogenic liquids released on water. The experiment was performed by spilling five different amounts of liquid nitrogen at different release rates and initial water temperatures. The vaporization mass fluxes of liquid nitrogen were determined directly from the mass loss measured during the experiment. A variation of initial vaporization fluxes and a subsequent shift in heat transfer mechanism were observed with changes in initial water temperature. The initial vaporization fluxes were directly dependent on the liquid nitrogen spill rate. The heat flux from water to liquid nitrogen determined from experimental data was validated with two theoretical correlations for convective boiling. It was also observed from validation with correlations that liquid nitrogen was found to be predominantly in the film boiling regime. The substantial results provide a suitable procedure for predicting the heat flux from water to cryogenic liquids that is required for source term modeling. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Simulation of water vapor condensation on LOX droplet surface using liquid nitrogen

    Science.gov (United States)

    Powell, Eugene A.

    1988-01-01

    The formation of ice or water layers on liquid oxygen (LOX) droplets in the Space Shuttle Main Engine (SSME) environment was investigated. Formulation of such ice/water layers is indicated by phase-equilibrium considerations under conditions of high partial pressure of water vapor (steam) and low LOX droplet temperature prevailing in the SSME preburner or main chamber. An experimental investigation was begun using liquid nitrogen as a LOX simulant. A monodisperse liquid nitrogen droplet generator was developed which uses an acoustic driver to force the stream of liquid emerging from a capillary tube to break up into a stream of regularly space uniformly sized spherical droplets. The atmospheric pressure liquid nitrogen in the droplet generator reservoir was cooled below its boiling point to prevent two phase flow from occurring in the capillary tube. An existing steam chamber was modified for injection of liquid nitrogen droplets into atmospheric pressure superheated steam. The droplets were imaged using a stroboscopic video system and a laser shadowgraphy system. Several tests were conducted in which liquid nitrogen droplets were injected into the steam chamber. Under conditions of periodic droplet formation, images of 600 micron diameter liquid nitrogen droplets were obtained with the stroboscopic video systems.

  14. Renewable energy carriers: Hydrogen or liquid air/nitrogen?

    International Nuclear Information System (INIS)

    Li Yongliang; Chen Haisheng; Zhang Xinjing; Tan Chunqing; Ding Yulong

    2010-01-01

    The world's energy demand is met mainly by the fossil fuels today. The use of such fuels, however, causes serious environmental issues, including global warming, ozone layer depletion and acid rains. A sustainable solution to the issues is to replace the fossil fuels with renewable ones. Implementing such a solution, however, requires overcoming a number of technological barriers including low energy density, intermittent supply and mobility of the renewable energy sources. A potential approach to overcoming these barriers is to use an appropriate energy carrier, which can store, transport and distribute energy. The work to be reported in this paper aims to assess and compare a chemical energy carrier, hydrogen, with a physical energy carrier, liquid air/nitrogen, and discuss potential applications of the physical carrier. The ocean energy is used as an example of the renewable energy sources in the work. The assessment and comparison are carried out in terms of the overall efficiency, including production, storage/transportation and energy extraction. The environmental impact, waste heat recovery and safety issues are also considered. It is found that the physical energy carrier may be a better alternative to the chemical energy carrier under some circumstances, particularly when there are waste heat sources.

  15. Design Tool for Liquid-Nitrogen Gaps in Superconducting Apparatus

    International Nuclear Information System (INIS)

    Pace, Marshall O.; Sauers, Isidor; James, David Randy; Tuncer, Enis; Polyzos, Georgios

    2011-01-01

    For designers of high temperature superconducting equipment with liquid nitrogen as a dielectric, an expedient universal curve is sought that provides breakdown strength for a specified class of electrode shapes, with any practical sizes of electrodes and gap; thus the universal curve fills in missing experimental data. Universal breakdown strength curves at pressures of or slightly above 100 kPa, are being developed for AC, DC or impulse stress for the class with sphere-sphere, plane-plane and sphere-plane gaps, with three independent parameters: the size of each electrode and gap. A user can normalize his parameters and find the corresponding breakdown strength, even though no data were available for his exact dimensions. For AC and DC stresses the geometrical effects of stressed area/volume are incorporated from most published AC and DC experimental data of the last 50 years, by plotting breakdown field versus new geometrical quantities, such that all data fall approximately on or near one normalized universal curve. This avoids the usual difficult task of calculating stressed area and volume effects on the breakdown values for the graph ordinate. For impulse stress a more traditional plot suffices to produce a universal curve. This suggests that area/volume effects might not be so important with impulse stress. If the method proves reliable, it may be possible to determine design parameters for a broad range of geometries, help unify seemingly disparate breakdown data in the literature, and provide easily used, practical guidance for designers.

  16. Connection for transfer of Liquid Nitrogen from High Voltage to ground potential

    DEFF Research Database (Denmark)

    Rasmussen, Claus Nygaard; Hansen, Finn; Willén, Dag

    2001-01-01

    In order to operate a superconducting cable conductor it must be kept at a cryogenic temperature (e.g. using liquid nitrogen). The superconducting cable conductor is at high voltage and the cooling equipment is kept at ground potential. This requires a thermally insulating connection that is also...... properties and withstand towards high-pressure liquid nitrogen. The length per joint is approximately 900 mm, including a Johnstoncoupling. The joints are tested in a closed liquid nitrogen circuit, with a pressure of up to 10 bars. The rated voltage of the cable system is 36 kV (phase-phase)....

  17. Liquid absorbent solutions for separating nitrogen from natural gas

    Science.gov (United States)

    Friesen, Dwayne T.; Babcock, Walter C.; Edlund, David J.; Lyon, David K.; Miller, Warren K.

    2000-01-01

    Nitrogen-absorbing and -desorbing compositions, novel ligands and transition metal complexes, and methods of using the same, which are useful for the selective separation of nitrogen from other gases, especially natural gas.

  18. Critical discharge of initially subcooled water through slits

    International Nuclear Information System (INIS)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  20. The reaction between barium and nitrogen in liquid sodium: resistivity studies

    International Nuclear Information System (INIS)

    Addison, C.C.; Creffield, G.K.; Hubberstey, P.; Pulham, R.J.

    1976-01-01

    The reaction of nitrogen with solutions of barium (between 0.34 and 6.89 mol % Ba) in liquid sodium at 573 K has been followed by changes in the electrical resistivity of the liquid. The capillary method has been employed, continuous sampling during reaction being achieved by electromagnetic pumping. The initial solution of nitrogen in the metal, followed by precipitation of barium and nitrogen from sodium as the nitride Ba 2 N, are reflected in the resistivity changes. The solubility of nitrogen in the alloy is a linear function of the barium concentration: S(mol % N) = x/4 (0 <= x <= 6.89 mol % Ba). This and the decrease in resistivity which invariably occurs during the solution process, provides additional information on the nature of solvation of nitrogen in solution in the liquid metal. (author)

  1. The verification of subcooled boiling models in CFX-4.2 at low pressure in annulus channel flow

    International Nuclear Information System (INIS)

    Kim, Seong-Jin; Kim, Moon-Oh; Park, Goon-Cherl

    2003-01-01

    Heat transfer in subcooled boiling is an important issue to increase the effectiveness of design and safety in operation of engineering system such as nuclear plant. The subcooled boiling, which may occur in the hot channel of reactor in normal state and in decreased pressure condition in transient state, can cause multi-dimensional and complicated respects. The variation of local heat transfer phenomena is created by changing of liquid and vapor velocity, by simultaneous bubble break-ups and coalescences, and by corresponding to bubble evaporation and condensation, and that can affect the stability of the system. The established researches have carried out not a point of local distributions of two-phase variables, but a point of systematical distributions, mostly. Although the subcooled boiling models have been used to numerical analysis using CFX-4.2, there are few verification of subcooled boiling models. This paper demonstrated locally and systematically the validation of subcooled boiling model in numerical calculations using CFX-4.2 especially, in annulus channel flow condition in subcooled boiling at low pressure with respect to subcooled boiling models such as mean bubble diameter model, bubble departure diameter model or wall heat flux model and models related with phase interface. (author)

  2. 14 MeV INAA nitrogen determination in coal conversion liquids

    International Nuclear Information System (INIS)

    Ehmann, W.D.; Khalil, S.R.

    1980-01-01

    Fast neutron activation analysis has been used for the direct determination of nitrogen in coal conversion liqui-ds. In our previous work on coals, solid standards such as N-1-napthylacetamide, NBS SRM 912 urea and NBS SRM 148 nicotinic acid were used for nitrogen determinations. In this work, a set of organic liquids was selected and evaluated for use as nitrogen standards in the analysis of coal-derived liquids. The use of the liquid standards minimizes problems associated with maintaining uniform irradation and counting geometries and self absorption differences related to varying matrix densities. The standard liquids were selected using criteria of high boiling point, well-defined stoichiometry, high-purity, non-hygroscopic nature and simple C-H-N elemental compositions. Excellent agreement between the 14 MeV INAA data and calculated stoichiometric values has been demonstrated for liquids with nitrogen contents from 1.89 to 39.95%. The liquid standards have been used to determine nitrogen in a set of typical coal conversion liquids and several international standards. (author)

  3. Control of the nitrogen concentration in liquid lithium by the hot trap method

    International Nuclear Information System (INIS)

    Sakurai, Toshiharu; Yoneoka, Toshiaki; Tanaka, Satoru; Suzuki, Akihiro; Muroga, Takeo

    2002-01-01

    The nitrogen concentration in liquid lithium was controlled by the hot-trap method. Titanium, vanadium and a V-Ti alloy were used as nitrogen gettering materials. Gettering experiments were conducted at 673, 773 and 823 K for 0.4-2.8 Ms. After immersion, the nitrogen concentration increased in titanium and V-Ti were tested at 823 K. Especially the nitrogen gettering effect by the V-10at.%Ti alloy was found to be large. Nitrogen was considered to exist mainly as solid solution in the V-10at.%Ti alloy. The decrease of the nitrogen concentration in liquid lithium by the V-Ti gettering was also confirmed

  4. DETERMINATION OF HEAT TRANSFER COEFFICIENTS FOR FRENCH PLASTIC SEMEN STRAW SUSPENDED IN STATIC NITROGEN VAPOR OVER LIQUID NITROGEN.

    Science.gov (United States)

    Santo, M V; Sansinena, M; Chirife, J; Zaritzky, N

    2015-01-01

    The use of mathematical models describing heat transfer during the freezing process is useful for the improvement of cryopreservation protocols. A widespread practice for cryopreservation of spermatozoa of domestic animal species consists of suspending plastic straws in nitrogen vapor before plunging into liquid nitrogen. Knowledge of surface heat transfer coefficient (h) is mandatory for computational modelling; however, h values for nitrogen vapor are not available. In the present study, surface heat transfer coefficients for plastic French straws immersed in nitrogen vapor over liquid nitrogen was determined; vertical and horizontal positions were considered. Heat transfer coefficients were determined from the measurement of time-temperature curves and from numerical solution of heat transfer partial differential equation under transient conditions using finite elements. The h values experimentally obtained for horizontal and vertically placed straws were compared to those calculated using correlations based on the Nusselt number for natural convection. For horizontal straws the average obtained value was h=12.5 ± 1.2 W m(2) K and in the case of vertical straws h=16 ± 2.48 W m(2) K. The numerical simulation validated against experimental measurements, combined with accurate h values provides a reliable tool for the prediction of freezing curves of semen-filled straws immersed in nitrogen vapor. The present study contributes to the understanding of the cryopreservation techniques for sperm freezing based on engineering concepts, improving the cooling protocols and the manipulation of the straws.

  5. New displacement sensor for a hybrid magnetic bearing in liquid nitrogen

    International Nuclear Information System (INIS)

    Komori, M.; Kobayashi, H.; Shiraishi, C.

    1999-01-01

    This paper describes a newly developed displacement sensor. The displacement sensor is used for a hybrid magnetic bearing in liquid nitrogen. The principle of the displacement sensor is based on a differential transformer. The sensor is found to be useful in liquid nitrogen at 77 K (-196 C). Moreover, the sensor is applied to a hybrid magnetic bearing. The displacement sensor is found to be useful and promising

  6. Solubility of Hydrogen and Nitrogen in liquid cast iron during melting and mold filling

    OpenAIRE

    Diószegi, Attila; Elfsberg, Jessica; Diószegi, Zoltán

    2016-01-01

    Defect formation like gas- and shrinkage porosity at cast iron component production is related to the content of gaseous elements in the liquid metal. The present work investigate the solubility of hydrogen and nitrogen in liquid iron aimed for production of lamellar and compacted graphite cast iron. The used methods and instruments are a combination of commercial measuring devices and novel experimental assemblies for measuring solubility of hydrogen and nitrogen during melting and mold fill...

  7. Chemical equilibrium calculations for the high pressure and temperature dissociation of liquid nitrogen

    Energy Technology Data Exchange (ETDEWEB)

    Hamilton, D.C.; Ree, F.H.

    1987-07-01

    Calculations are reported for the equation-of-state properties of shock-compressed liquid nitrogen. The statistical mechanical, chemical equilibrium calculations, which allow for the simultaneous presence of both the diatomic and monatomic forms of nitrogen, show good agreement with recent dynamic experiments.

  8. Chemical equilibrium calculations for the high pressure and temperature dissociation of liquid nitrogen

    International Nuclear Information System (INIS)

    Hamilton, D.C.; Ree, F.H.

    1987-07-01

    Calculations are reported for the equation-of-state properties of shock-compressed liquid nitrogen. The statistical mechanical, chemical equilibrium calculations, which allow for the simultaneous presence of both the diatomic and monatomic forms of nitrogen, show good agreement with recent dynamic experiments

  9. Propagation of Local Bubble Parameters of Subcooled Boiling Flow in a Pressurized Vertical Annulus Channel

    International Nuclear Information System (INIS)

    Chu, In-Cheol; Lee, Seung Jun; Youn, Young Jung; Park, Jong Kuk; Choi, Hae Seob; Euh, Dong Jin

    2015-01-01

    CMFD (Computation Multi-Fluid Dynamics) tools have been being developed to simulate two-phase flow safety problems in nuclear reactor, including the precise prediction of local bubble parameters in subcooled boiling flow. However, a lot of complicated phenomena are encountered in the subcooled boiling flow such as bubble nucleation and departure, interfacial drag of bubbles, lateral migration of bubbles, bubble coalescence and break-up, and condensation of bubbles, and the constitutive models for these phenomena are not yet complete. As a result, it is a difficult task to predict the radial profile of bubble parameters and its propagation along the flow direction. Several experiments were performed to measure the local bubble parameters for the validation of the CMFD code analysis and improvement of the constitutive models of the subcooled boiling flow, and to enhance the fundamental understanding on the subcooled boiling flow. The information on the propagation of the local flow parameters along the flow direction was not provided because the measurements were conducted at the fixed elevation. In SUBO experiments, the radial profiles of local bubble parameters, liquid velocity and temperature were obtained for steam-water subcooled boiling flow in a vertical annulus. The local flow parameters were measured at six elevations along the flow direction. The pressure was in the range of 0.15 to 0.2 MPa. We have launched an experimental program to investigate quantify the local subcooled boiling flow structure under elevated pressure condition in order to provide high precision experimental data for thorough validation of up-to-date CMFD codes. In the present study, the first set of experimental data on the propagation of the radial profile of the bubble parameters was obtained for the subcooled boiling flow of R-134a in a pressurized vertical annulus channel. An experimental program was launched for an in-depth investigation of a subcooled boiling flow in an elevated

  10. Turbulent subcooled boiling flow visualization experiments through a rectangular channel

    International Nuclear Information System (INIS)

    Estrada-Perez, Carlos E.; Dominguez-Ontiveros, Elvis E.; Hassan, Yassin A.

    2008-01-01

    Full text of publication follows: Proper characterization of subcooled boiling flow is of importance in many applications. It is of exceptional significance in the development of empirical models for the design of nuclear reactors, steam generators, and refrigeration systems. Most of these models are based on experimental studies that share the characteristics of utilizing point measurement probes with high temporal resolution, e.g. Hot Film Anemometry (HFA), Laser Doppler Velocimetry (LDV), and Fiber Optic Probes (FOP). However there appears to be a scarcity of experimental studies that can capture instantaneous whole-field measurements with a fast time response. Particle Tracking Velocimetry (PTV) may be used to overcome the limitations associated with point measurement techniques. PTV is a whole-flow-field technique providing instantaneous velocity vectors capable of high spatial and temporal resolution. PTV is also an exceptional tool for the analysis of boiling flow due to its ability to differentiate between the gas and liquid phases and subsequently deliver independent velocity fields associated with each phase. In this work, using PTV, liquid velocity fields of a turbulent subcooled boiling flow in a rectangular channel were successfully obtained. The present results agree with similar studies that used point measurement probes. However, the present study provides additional information; not only averaged profiles of the velocity components were obtained, instantaneous 2-D velocity fields were also readily available with a high temporal and spatial resolution. Analysis of fluctuating velocities, Reynolds stresses, and higher order statistics of the flow are presented. This work is an attempt to enrich the database already collected on turbulent subcooled boiling flow, with the hope that it will be useful in turbulence modeling efforts. (authors)

  11. The formation of nitrogeneous compounds in the γ-radiolyses of liquid nitrogen solutions of hydrogen, methane, and ethane

    International Nuclear Information System (INIS)

    Horigome, Keiichi; Hirokami, Shun-ichi; Sato, Shin

    1978-01-01

    The γ-radiolyses of liquid nitrogen solutions of hydrogen, methane, and ethane have been reinvestigated. A complete survey of nitrogen-containing products has been attempted. The nitrogeneous compounds observed were ammonia (0.7) and hydrogen azide (0.02) in the case of hydrogen, ammonia (0.3), hydrogen cyanide (0.1), methyl azide (0.01), and a polymer in the case of methane, and ammonia (0.3), hydrogen cyanide (0.05), acetonitrile (0.04), ethyl azide (0.01), and a polymer in the case of ethane. The values in parentheses are the G-values obtained at optimum conditions. The hydrolysis of the polymer obtained with methane gave formaldehyde in amounts which correspond to the fact that the G-value of the nitrogen atoms which were converted into the polymer is about 1.0. In order to explain these results, possible reaction mechanisms are discussed. (auth.)

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

    International Nuclear Information System (INIS)

    Munoz-Cobo, J.L.; Chiva, S.; Escriva, A.

    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 the subcooled boiling region, the average void fraction in the bulk-boiling region, the mass fluxes at the boiling boundary and the channel exit, respectively, and so on. Each channel has three nodes, one of liquid, one with subcooled boiling, and one with bulk boiling. The reduced order model includes also a modal kinetics with the fundamental mode and the first subcritical one, and two channels representing both halves of the reactor core. Also, in this paper, we perform a detailed study of the way to calculate the feedback reactivity parameters. The model displays out-of-phase oscillations when enough feedback gain is provided. The feedback gain that is necessary to self-sustain these oscillations is approximately one-half the gain that is needed when the subcooled boiling node is not included

  13. Forced convective and subcooled flow boiling heat transfer to pure water and n-heptane in an annular heat exchanger

    International Nuclear Information System (INIS)

    Peyghambarzadeh, S.M.; Sarafraz, M.M.; Vaeli, N.; Ameri, E.; Vatani, A.; Jamialahmadi, M.

    2013-01-01

    Highlights: ► The cooling performance of water and n-heptane is compared during subcooled flow boiling. ► Although n-heptane leaves the heat exchanger warmer it has a lower heat transfer coefficient. ► Flow rate, heat flux and degree of subcooling have direct effect on heat transfer coefficient. ► The predictions of some correlations are evaluated against experimental data. - Abstract: In this research, subcooled flow boiling heat transfer coefficients of pure n-heptane and distilled water at different operating conditions have been experimentally measured and compared. The heat exchanger consisted of vertical annulus which is heated from the inner cylindrical heater with variable heat flux (less than 140 kW/m 2 ). Heat flux is varied so that two different flow regimes from single phase forced convection to nucleate boiling condition are created. Meanwhile, liquid flow rate is changed in the range of 2.5 × 10 −5 –5.8 × 10 −5 m 3 /s to create laminar up to transition flow regimes. Three subcooling levels including 10, 20 and 30 °C are also considered. Experimental results demonstrated that subcooled flow boiling heat transfer coefficient increases when higher heat flux, higher liquid flow rate and greater subcooling level are applied. Furthermore, influence of the operating conditions on the bubbles generation on the heat transfer surface is also discussed. It is also shown that water is better cooling fluid in comparison with n-heptane

  14. Calorimetry by immersion into liquid nitrogen and liquid argon: a better way to determine the internal surface area of micropores.

    Science.gov (United States)

    Navarrete, Ricardo; Llewellyn, Philip; Rouquerol, Françoise; Denoyel, Renaud; Rouquerol, Jean

    2004-09-15

    The aim of this work is to assess the internal surface area of a set of samples (either carbons or oxides, either porous or nonporous, either microporous or mesoporous) by microcalorimetry via immersion into liquid nitrogen or argon. We have made use of an isothermal, heat-flux microcalorimeter, initially designed and built in our laboratory for the sake of gas adsorption experiments at 77 or 87 K. It seems that immersion calorimetry into liquid nitrogen and argon makes it possible to go one step further in the determination of the internal surface area of micropores.

  15. Kinetics and mechanisms of interactions of nitrogen and carbon monoxide with liquid niobium

    International Nuclear Information System (INIS)

    Park, H.G.

    1990-01-01

    The kinetics and mechanisms of interactions of N 2 and CO with liquid niobium were investigated in the temperature range of 2,700 to 3,000 K in samples levitated in N 2 /Ar and CO/Ar streams. The nitrogen absorption and desorption processes were found to be second-order with respect to nitrogen concentration, indicating that the rate controlling step is either the adsorption of nitrogen molecules on the liquid surface or dissociation of absorbed nitrogen molecules into adsorbed atoms. The carbon and oxygen dissolution in liquid niobium from CO gas is an exothermic process and the solubilities of carbon and oxygen (C Ce , C Oe in at%) are related to the temperature and the partial pressure of CO. The reaction CO → [C] + [O] along with the evaporation of niobium oxide takes place during C and O dissolution, whereas C and O desorption occurs via CO evolution only

  16. Thermodynamic Modeling and Mechanical Design of a Liquid Nitrogen Vaporization and Pressure Building Device

    Science.gov (United States)

    Leege, Brian J.

    The design of a liquid nitrogen vaporization and pressure building device that has zero product waste while recovering some of its stored energy is of interest for the cost reduction of nitrogen for use in industrial processes. Current devices may waste up to 30% of the gaseous nitrogen product by venting it to atmosphere. Furthermore, no attempt is made to recover the thermal energy available in the coldness of the cryogen. A seven step cycle with changing volumes and ambient heat addition is proposed, eliminating all product waste and providing the means of energy recovery from the nitrogen. This thesis discusses the new thermodynamic cycle and modeling as well as the mechanical design and testing of a prototype device. The prototype was able to achieve liquid nitrogen vaporization and pressurization up to 1000 psi, while full cycle validation is ongoing with promising initial results.

  17. Liquid Nitrogen (-196°C effect under pollen of some cultured or ornamental species

    Directory of Open Access Journals (Sweden)

    Sabina GLIGOR

    2006-05-01

    Full Text Available The criopreservation involve the stock of the vegetal material at low temperatures (-196°C in liquid nitrogen, in thermal conditions in which the division of cells and metabolic processes slow down, thus that the samplings may be conserved for long periods without suffering any genetic modifications. This stock technique is applied till present only on 80 vegetal species, keeping their seeds and vitrocultures preponderantly; researches were made regarding the maintenance of pollen in liquid nitrogen.The mature pollen, able to resist a higher degree of desiccation, may be conserved at low temperatures, without criopreservation. It was made researches on criopreservation of rise, maize, wheat, roses, sun flower and soy pollen. Our study purpose was to follow the impact of liquid nitrogen (-196°C about on viability of some cultured and ornamental species. The designed time of criopreservation it was 30 minutes and 7 days, using the TTC (tripheniltetrazole chloride method which allows testing the viability of vegetal material based on dehydrogenase activity.It was observed at Petunia hybrida species, that the pollen viability was low - in relevance with the witness represented from the pollen which was not resigned to the nitrogen liquid treatment - between percentage limits of 3.5-8%, in the case when the vegetal material was submersed 30 minutes in liquid nitrogen and 7.5-14.5% 7 days at (-196°C. The submersing of Nicotiana alata var. grandiflora species at 7 days, determined a low viability with 11.53%. The following two studied species Cucurbita and Hosta were proved to be the most resistant at submersing and maintenance in liquid nitrogen. The most affected pollen was Campsis radicans species. At Datura stramonium species was observed 2.59% a low viability of pollen, after 30 minutes of liquid nitrogen treatment, was 19.56%, after 7 days of submersing, the most pollen granules losing completely their viability.

  18. Vitrification of human pronuclear oocytes by direct plunging into cooling agent: Non sterile liquid nitrogen vs. sterile liquid air.

    Science.gov (United States)

    Isachenko, Vladimir; Todorov, Plamen; Seisenbayeva, Akerke; Toishibekov, Yerzhan; Isachenko, Evgenia; Rahimi, Gohar; Mallmann, Peter; Foth, Dolores; Merzenich, Markus

    2018-02-01

    In fact, a full sterilization of commercially-produced liquid nitrogen contaminated with different pathogens is not possible. The aim of this study was to compare the viability of human pronuclear oocytes subjected to cooling by direct submerging of open carrier in liquid nitrogen versus submerging in clean liquid air (aseptic system). One- and three-pronuclei stage embryos (n = 444) were cryopreserved by direct plunging into liquid nitrogen (vitrified) in ethylene glycol (15%), dimethylsulphoxide (15%) and 0.2M sucrose. Oocytes were exposed in 20, 33, 50 and 100% vitrification solution for 2, 1 and 1 min, and 30-50 s, respectively at room temperature. Then first part of oocytes (n = 225) were directly plunged into liquid nitrogen, and second part of oocytes (n = 219) into liquid air. Oocytes were thawed rapidly at a speed of 20,000 °C/min and then subsequently were placed into a graded series of sucrose solutions (0.5, 0.25, 0.12 and 0.06M) at 2.5 min intervals and cultured in vitro for 3 days. In both groups, the rate of high-quality embryos (Grade 6A: 6 blastomeres, no fragmentation; Grade 8A: 8 blastomeres, no fragmentation; Grade 8A compacting: 8 blastomeres, beginning of compacting) was noted. The rates of high-quality embryos developed from one-pronuclear oocytes vitrified by cooling in liquid nitrogen and liquid air were: 39.4% ± 0.6 and 38.7% ± 0.8, respectively (P > 0.1). These rates for three-pronuclear oocytes were: 45.8 ± 0.8% and 52.0 ± 0.7%, respectively (P liquid air (aseptic system) is a good alternative for using of not sterile liquid nitrogen. Copyright © 2017. Published by Elsevier Inc.

  19. Numerical study on the flow and heat transfer characteristics of slush nitrogen in a corrugated pipe

    Science.gov (United States)

    Li, Y. J.; Wu, S. Q.; Jin, T.

    2017-12-01

    Slush nitrogen has lower temperature, higher density and higher heat capacity than that of liquid nitrogen at normal boiling point. It is considered to be a potential coolant for high-temperature superconductive cables (HTS) that would decrease nitrogen consumption and storage cost. The corrugated pipe can help with the enhancement of heat transfer and flexibility of the coolants for HTS cables. In this paper, a 3-D Euler-Euler two-fluid model has been developed to study the flow and heat transfer characteristics of slush nitrogen in a horizontal helically corrugated pipe. By comparing with the empirical formula for pressure drop, the numerical model is confirmed to be effective for the prediction of slush nitrogen flow in corrugated pipes. The flow and heat transfer characteristics of slush nitrogen in a horizontal pipe at various working conditions (inlet solid fraction of 0-20%, inlet velocity of 0-3 m/s, heat flux of 0-12 kW/m2) have been analyzed. The friction factor of slush nitrogen is lower than that of subcooled liquid nitrogen when the slush Reynolds number is higher than 4.2×104. Moreover, the heat transfer coefficient of slush nitrogen flow in the corrugated pipe is higher than that of subcooled liquid nitrogen at velocities which is higher than that 1.76 m/s, 0.91 m/s and 0.55 m/s for slush nitrogen with solid fraction of 5%, 10% and 20%, respectively. The slush nitrogen has been confirmed to have better heat transfer performance and lower pressure drop instead of using liquid nitrogen flowing through a helically corrugated pipe.

  20. Control of nitrogen concentration in liquid lithium by iron-titanium alloy

    International Nuclear Information System (INIS)

    Hirakane, Shinji; Yoneoka, Toshiaki; Tanaka, Satoru

    2006-01-01

    Reducing the nitrogen concentration in liquid lithium is one of the most important steps in creating a liquid lithium blanket system. In this study, in order to verify the nitrogen gettering performance of Fe-Ti alloy, the variation in the nitrogen concentration in liquid lithium, into which Fe-10 at.% Ti or Fe-5 at.% Ti getter was immersed, was examined. The results confirmed a gettering performance of Fe-Ti alloy comparable to that of V-Ti alloy, although the effects were not durable in either the Fe-Ti or the V-Ti alloy. After the immersion test, the existing states of nitrogen absorbed in the gettering material were analyzed by means of XRD, XMA and XPS. TiN and some nitrogen dissolved in α-Fe without forming TiN were observed. It was indicated that nitrogen gettering is prevented not only by the surface nitrides, but also by the internal diffusion barriers originating from the absorbed nitrogen

  1. An explanation for why it is difficult to form slush nitrogen from liquid nitrogen used previously for this purpose.

    Science.gov (United States)

    Baker, Michael J; Denton, Travis T; Herr, Charles

    2013-02-01

    Slush nitrogen (SN) is used to avoid the Leidenfrost effect, which is problematic when using liquid nitrogen (LN). Slush nitrogen's usefulness has been demonstrated by its requirement for the successful cryopreservation of insect embryos. To convert LN to SN, typically, the pressure above a Dewar of LN is reduced, using a vacuum pump in a sealed system until conversion occurs. It has been observed that LN from a fresh tank will readily produce SN; however, repeated use of the same LN results in the inability to form SN in subsequent trials. The current experiments were designed to identify the cause of this phenomenon. The hypothesis is that gaseous oxygen from the surrounding, ambient air condenses and mixes with the LN to form a mixture with a lower freezing point and; therefore, prevents the formation of SN. The hypothesis was tested and found to be true. Copyright © 2012. Published by Elsevier Inc.

  2. Cellulitis Secondary to Liquid Nitrogen Cryotherapy: Case Report and Literature Review.

    Science.gov (United States)

    Huang, Christina M; Lu, Emily Y; Kirchhof, Mark G

    Liquid nitrogen cryotherapy is a commonly used technique to treat a wide variety of dermatologic conditions including actinic keratoses, non-melanoma skin cancers, verrucae, and seborrheic keratoses. The risks associated with liquid nitrogen cryotherapy are important to know and discuss with patients prior to treatment. We report a case of cellulitis secondary to liquid nitrogen cryotherapy for actinic keratosis. We sought to review the literature for an estimate of secondary infection rates following cryotherapy treatment. We searched Pubmed using the terms cryotherapy and infection or cellulitis. We then looked at articles classified as clinical trials where cryotherapy was used to treat skin conditions. We then selected clinical trials that listed cellulitis or infection as an adverse event. There were no case reports, case series, or review articles detailing the risk of infection from liquid nitrogen cryotherapy. We found 8 articles classified as clinical trials on Pubmed that did list infection as an adverse event. The risk of infection from these studies varied from approximately 2% to 30%. There was a great degree of heterogeneity in treatment sites, length of treatment, and treatment targets. While it is difficult to determine the true incidence of infection from liquid nitrogen cryotherapy, clinicians should endeavor to inform patients of this potential risk.

  3. Needling versus liquid nitrogen cryotherapy for the treatment of pedal warts a randomized controlled pilot study.

    Science.gov (United States)

    Cunningham, Daniel J; Brimage, Jessica T; Naraghi, Reza N; Bower, Virginia M

    2014-07-01

    We hypothesized that needling of a pedal wart creates local inflammation and a subsequent cell-mediated immune response (CMIR) against human papillomavirus. The primary objective of this study was to investigate whether needling to induce a CMIR against human papillomavirus is an effective treatment for pedal warts compared with liquid nitrogen cryotherapy. A secondary objective was to investigate whether the CMIR induced by needling is effective against satellite pedal warts. Eligible patients with pedal warts were randomly allocated to receive either needling or liquid nitrogen cryotherapy. Only the primary pedal wart was treated during the study. Follow-up was 12 weeks, with outcome assessments made independently under blinded circumstances. Of 37 patients enrolled in the study, 18 were allocated to receive needling and 19 to receive liquid nitrogen cryotherapy. Regression of the primary pedal wart occurred in 64.7% of the needling group (11 of 17) and in 6.2% of the liquid nitrogen cryotherapy group (1 of 16) (P =  .001). No significant relationship was found between needling of the primary pedal wart and regression of satellite pedal warts (P = .615) or complete pedal wart regression (P = .175). There was no significant difference in pain, satisfaction, or cosmesis between the two groups. The regression rate of the primary pedal wart was significantly higher in the needling group compared with the liquid nitrogen cryotherapy group.

  4. Comparison of cryopreserved human sperm in vapor and liquid phases of liquid nitrogen: effect on motility parameters, morphology, and sperm function.

    Science.gov (United States)

    Punyatanasakchai, Piyaphan; Sophonsritsuk, Areephan; Weerakiet, Sawaek; Wansumrit, Surapee; Chompurat, Deonthip

    2008-11-01

    To compare the effects of cryopreserved sperm in vapor and liquid phases of liquid nitrogen on sperm motility, morphology, and sperm function. Experimental study. Andrology laboratory at Ramathibodi Hospital, Thailand. Thirty-eight semen samples with normal motility and sperm count were collected from 38 men who were either patients of an infertility clinic or had donated sperm for research. Each semen sample was divided into two aliquots. Samples were frozen with static-phase vapor cooling. One aliquot was plunged into liquid nitrogen (-196 degrees C), and the other was stored in vapor-phase nitrogen (-179 degrees C) for 3 days. Thawing was performed at room temperature. Motility was determined by using computer-assisted semen analysis, sperm morphology was determined by using eosin-methylene blue staining, and sperm function was determined by using a hemizona binding test. Most of the motility parameters of sperm stored in the vapor phase were not significantly different from those stored in the liquid phase of liquid nitrogen, except in amplitude of lateral head displacement. The percentages of normal sperm morphology in both vapor and liquid phases also were not significantly different. There was no significant difference in the number of bound sperm in hemizona between sperm cryopreserved in both vapor and liquid phases of liquid nitrogen. Cryopreservation of human sperm in a vapor phase of liquid nitrogen was comparable to cryopreservation in a liquid phase of liquid nitrogen.

  5. Liquid Transfer Cryogenic Test Facility: Initial hydrogen and nitrogen no-vent fill data

    Science.gov (United States)

    Moran, Matthew E.; Nyland, Ted W.; Papell, S. Stephen

    1990-01-01

    The Liquid Transfer Cryogenic Test Facility is a versatile testbed for ground-based cryogenic fluid storage, handling, and transfer experimentation. The test rig contains two well instrumented tanks, and a third interchangeable tank, designed to accommodate liquid nitrogen or liquid hydrogen testing. The internal tank volumes are approx. 18, 5, and 1.2 cu. ft. Tank pressures can be varied from 2 to 30 psia. Preliminary no vent fill tests with nitrogen and hydrogen were successfully completed with the test rig. Initial results indicate that no vent fills of nitrogen above 90 percent full are achievable using this test configuration, in a 1-g environment, and with inlet liquid temperatures as high as 143 R, and an average tank wall temperature of nearly 300 R. This inlet temperature corresponds to a saturation pressure of 19 psia for nitrogen. Hydrogen proved considerably more difficult to transfer between tanks without venting. The highest temperature conditions resulting in a fill level greater than 90 percent were with an inlet liquid temperature of 34 R, and an estimated tank wall temperature of slightly more than 100 R. Saturation pressure for hydrogen at this inlet temperature is 10 psia. All preliminary no vent fill tests were performed with a top mounted full cone nozzle for liquid injection. The nozzle produces a 120 degree conical droplet spray at a differential pressure of 10 psi. Pressure in the receiving tank was held to less than 30 psia for all tests.

  6. Reaction between barium and nitrogen in liquid sodium

    International Nuclear Information System (INIS)

    Addison, C.C.; Pulham, R.J.; Trevillion, E.A.

    1975-01-01

    Nitrogen in increasing amounts has been added to separate solutions of barium in sodium of constant composition (ca.4.40 mol % Ba) at 300 0 C. After rendering each mixture homogenous using an electromagnetic pump, filtration, and nitrogen analysis, all the N 2 added has been found in solution up to a solution composition approximating to Ba 4 N (i.e. 1.1 mol % N) beyond which the quantity of dissolved N 2 decreases progressively due to precipitation of the nitride Ba 2 N. The solubilization is interpreted in terms of strong preferential solvation of the nitride ion by barium cations. (author)

  7. Orbital storage and supply of subcritical liquid nitrogen

    Science.gov (United States)

    Aydelott, John C.

    1990-01-01

    Subcritical cryogenic fluid management has long been recognized as an enabling technology for key propulsion applications, such as space transfer vehicles (STV) and the on-orbit cryogenic fuel depots which will provide STV servicing capability. The LeRC Cryogenic Fluids Technology Office (CFTO), under the sponsorship of OAST, has the responsibility of developing the required technology via a balanced program involving analytical modeling, ground based testing, and in-space experimentation. Topics covered in viewgraph form include: cryogenic management technologies; nitrogen storage and supply; cryogenic nitrogen cooling capability; and LN2 system demonstration technical objectives.

  8. Influence of nitrogen loading and plant nitrogen assimilation on nitrogen leaching and N₂O emission in forage rice paddy fields fertilized with liquid cattle waste.

    Science.gov (United States)

    Riya, Shohei; Zhou, Sheng; Kobara, Yuso; Sagehashi, Masaki; Terada, Akihiko; Hosomi, Masaaki

    2015-04-01

    Livestock wastewater disposal onto rice paddy fields is a cost- and labor-effective way to treat wastewater and cultivate rice crops. We evaluated the influence of nitrogen loading rates on nitrogen assimilation by rice plants and on nitrogen losses (leaching and N2O emission) in forage rice fields receiving liquid cattle waste (LCW). Four forage rice fields were subjected to nitrogen loads of 107, 258, 522, and 786 kg N ha(-1) (N100, N250, N500, and N750, respectively) using basal fertilizer (chemical fertilizer) (50 kg N ha(-1)) and three LCW topdressings (each 57-284 kg N ha(-1)). Nitrogen assimilated by rice plants increased over time. However, after the third topdressing, the nitrogen content of the biomass did not increase in any treatment. Harvested aboveground biomass contained 93, 60, 33, and 31 % of applied nitrogen in N100, N250, N500, and N750, respectively. The NH4 (+) concentration in the pore water at a depth of 20 cm was less than 1 mg N L(-1) in N100, N250, and N500 throughout the cultivation period, while the NH4 (+) concentration in N750 increased to 3 mg N L(-1) after the third topdressing. Cumulative N2O emissions ranged from -0.042 to 2.39 kg N ha(-1); the highest value was observed in N750, followed by N500. In N750, N2O emitted during the final drainage accounted for 80 % of cumulative N2O emissions. This study suggested that 100-258 kg N ha(-1) is a recommended nitrogen loading rate for nitrogen recovery by rice plants without negative environmental impacts such as groundwater pollution and N2O emission.

  9. Subcooled boiling heat transfer to R 12 in an annular vertical channel

    Energy Technology Data Exchange (ETDEWEB)

    Braeuer, H.; Mayinger, F.

    1988-10-01

    Detailed knowledge of the physical phenomena involved in subcooled boiling is of great importance for the design of liquid-cooled heat generating systems with high heat fluxes. Experimental heat transfer data were obtained for forced convective boiling of dichloro-difluoroethane (R 12). The flow is circulated upwards through a concentric annular vertical channel. The inner and outer diameters of the annulus are 0.016 m and 0.03 m respectively. The reduced pressures studied were 0.24 less than or equal to p/p/sub crit/ less than or equal to 0.8, inlet subcooling varied from 10 to 75 K and mass fluxes from 500 to 3000 kg/m/sup 2/s, which corresponds to Re numbers from 30 000 to 300 000. The experiments, described in this study, demonstrate that liquid fluorocarbons show certain unusual boiling characteristics in the subcooled flow, such as hysteresis of the boiling curve. These characteristics are attributed to the properties of the fluid, mainly the Pr number and the very low surface tension. The pronounced boiling curve hysteresis can be explained by the fact that large nucleation sites may have been flooded prior to incipient boiling. A dimensionless regression formula is presented which predicts the onset of subcooled boiling as a function of reduced pressure (p/p/sub crit/), Boiling-(Bo), Reynolds-(Re), and a modified Jacob Number (Ja), over the whole range of parameters studied, with a good accuracy, including water data from literature.

  10. Numerical simulation of bubble behavior in subcooled flow boiling under velocity and temperature gradient

    International Nuclear Information System (INIS)

    Bahreini, Mohammad; Ramiar, Abas; Ranjbar, Ali Akbar

    2015-01-01

    Highlights: • Condensing bubble is numerically investigated using VOF model in OpenFOAM package. • Bubble mass reduces as it goes through condensation and achieves higher velocities. • At a certain time the slope of changing bubble diameter with time, varies suddenly. • Larger bubbles experience more lateral migration to higher velocity regions. • Bubbles migrate back to a lower velocity region for higher liquid subcooling rates. - Abstract: In this paper, numerical simulation of the bubble condensation in the subcooled boiling flow is performed. The interface between two-phase is tracked via the volume of fluid (VOF) method with continuous surface force (CSF) model, implemented in the open source OpenFOAM CFD package. In order to simulate the condensing bubble with the OpenFOAM code, the original energy equation and mass transfer model for phase change have been modified and a new solver is developed. The Newtonian flow is solved using the finite volume scheme based on the pressure implicit with splitting of operators (PISO) algorithm. Comparison of the simulation results with previous experimental data revealed that the model predicted well the behavior of the actual condensing bubble. The bubble lifetime is almost proportional to bubble initial size and is prolonged by increasing the system pressure. In addition, the initial bubble size, subcooling of liquid and velocity gradient play an important role in the bubble deformation behavior. Velocity gradient makes the bubble move to the higher velocity region and the subcooling rate makes it to move back to the lower velocity region.

  11. Numerical simulation of bubble behavior in subcooled flow boiling under velocity and temperature gradient

    Energy Technology Data Exchange (ETDEWEB)

    Bahreini, Mohammad, E-mail: m.bahreini1990@gmail.com; Ramiar, Abas, E-mail: aramiar@nit.ac.ir; Ranjbar, Ali Akbar, E-mail: ranjbar@nit.ac.ir

    2015-11-15

    Highlights: • Condensing bubble is numerically investigated using VOF model in OpenFOAM package. • Bubble mass reduces as it goes through condensation and achieves higher velocities. • At a certain time the slope of changing bubble diameter with time, varies suddenly. • Larger bubbles experience more lateral migration to higher velocity regions. • Bubbles migrate back to a lower velocity region for higher liquid subcooling rates. - Abstract: In this paper, numerical simulation of the bubble condensation in the subcooled boiling flow is performed. The interface between two-phase is tracked via the volume of fluid (VOF) method with continuous surface force (CSF) model, implemented in the open source OpenFOAM CFD package. In order to simulate the condensing bubble with the OpenFOAM code, the original energy equation and mass transfer model for phase change have been modified and a new solver is developed. The Newtonian flow is solved using the finite volume scheme based on the pressure implicit with splitting of operators (PISO) algorithm. Comparison of the simulation results with previous experimental data revealed that the model predicted well the behavior of the actual condensing bubble. The bubble lifetime is almost proportional to bubble initial size and is prolonged by increasing the system pressure. In addition, the initial bubble size, subcooling of liquid and velocity gradient play an important role in the bubble deformation behavior. Velocity gradient makes the bubble move to the higher velocity region and the subcooling rate makes it to move back to the lower velocity region.

  12. Dependence of bubble behavior in subcooled boiling on surface wettability

    International Nuclear Information System (INIS)

    Harada, Takahiro; Nagakura, Hiroshi; Okawa, Tomio

    2010-01-01

    This paper presents the results of visualization experiments that were carried out to investigate the dynamics of vapor bubbles generated in water pool boiling. In the experiments, vapor bubbles were generated on a vertical circular surface of a copper block containing nine cartridge heaters, and the contact angle of the heated surface was used as a main experimental parameter. The experiments were performed under subcooled as well as nearly saturated conditions. To enable clear observation of individual bubbles with a high speed camera, the heat flux was kept low enough to eliminate significant overlapping of bubbles. When the contact angle was small, the bubbles were lifted-off the vertical heated surface within a short period of time after the nucleation. On the other hand, when the contact angle was large, they slid up the vertical surface for a long distance. When bubbles were lifted-off the heated surface in subcooled liquid, bubble life-time was significantly shortened since bubbles collapsed rapidly due to condensation. It was shown that this distinct difference in bubble dynamics could be attributed to the effects of surface tension force.

  13. Fast-freezing with liquid nitrogen preserves bulk dissolved organic matter concentrations, but not its composition

    DEFF Research Database (Denmark)

    Thieme, Lisa; Graeber, Daniel; Kaupenjohann, Martin

    2016-01-01

    -freezing with liquid nitrogen) on DOM concentrations measured as organic carbon (DOC) concentrations and on spectroscopic properties of DOM from different terrestrial ecosystems (forest and grassland). Fresh and differently frozen throughfall, stemflow, litter leachate and soil solution samples were analyzed for DOC...... concentrations, UV-vis absorption and fluorescence excitation–emission matrices combined with parallel factor analysis (PARAFAC). Fast-freezing with liquid nitrogen prevented a significant decrease of DOC concentrations observed after freezing at −18 °C. Nonetheless, the share of PARAFAC components 1 (EXmax...... component 4 (EXmax: 280 nm, EXmax: 328 nm) to total fluorescence was not affected by freezing. We recommend fast-freezing with liquid nitrogen for preservation of bulk DOC concentrations of samples from terrestrial sources, whereas immediate measuring is preferable to preserve spectroscopic properties...

  14. Enucleation and liquid nitrogen cryotherapy in the treatment of keratocystic odontogenic tumors: a case series.

    Science.gov (United States)

    Tonietto, Leonardo; Borges, Hedelson Odenir Iecher; Martins, Carlos Alberto Medeiros; Silva, Daniela Nascimento; Sant'Ana Filho, Manoel

    2011-06-01

    This study describes the technique of lesion enucleation without capsule disruption combined with liquid nitrogen cryotherapy in the surgical treatment of keratocystic odontogenic tumors (KOTs). Eight patients (9 KOTs) were included in the study. After enucleation, liquid nitrogen was applied twice for 1 minute, with 5-minute intervals between applications. The patients were followed up for 3 to 9 years. There were no recurrences during the follow-up of 9 KOTs for up to 9 years. Only 1 patient had temporary reversible loss of lip sensation after treatment. There were no pathologic fractures. In all cases bone height at the surgical site was restored, and no patients needed bone reconstruction for post-treatment rehabilitation. This study confirmed the efficiency of KOT treatment enucleation without fragmentation combined with liquid nitrogen cryotherapy at the surgical site. Copyright © 2011 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

  15. Does Parmelina tiliacea lichen photosystem II survive at liquid nitrogen temperatures?

    Science.gov (United States)

    Oukarroum, Abdallah; El Gharous, Mohamed; Strasser, Reto J

    2017-02-01

    Parmelina tiliacea lichens kept in the wet and dry state were stored in liquid nitrogen for 1 week and the subsequent recovery of their photosynthetic apparatus was followed. The chlorophyll a fluorescence rise and the maximum quantum yield of primary photochemistry φ Po (F V /F M ) were analysed for this purpose. Storage of wet thalli for 1 week in liquid nitrogen led to an impairment of photosystem II and probably the photosynthetic apparatus as a whole, from which the thalli did not recover over time. Thalli exposed in the dry state thalli were far less affected by the treatment and recovered well. These results indicate that the thalli are extremely tolerant to liquid nitrogen temperatures only in the dry state. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. Solutions for Liquid Nitrogen Pre-Cooling in Helium Refrigeration Cycles

    CERN Document Server

    Wagner, U

    2000-01-01

    Pre-cooling of helium by means of liquid nitrogen is the oldest and one of the most common process features used in helium liquefiers and refrigerators. Its two principle tasks are to allow or increase the rate of pure liquefaction, and to permit the initial cool-down of large masses to about 80 K. Several arrangements for the pre-cooling process are possible depending on the desired application. Each arrangement has its proper advantages and drawbacks. The aim of this paper is to review the possible process solutions for liquid nitrogen pre-cooling and their particularities.

  17. Viability of Bacillus popilliae after Lyophilization of Liquid Nitrogen Frozen Cells1

    Science.gov (United States)

    Lingg, A. J.; Mcmahon, K. J.; Herzmann, Cheryl

    1967-01-01

    The per cent viability of Bacillus popilliae after lyophilization of liquid nitrogen frozen cells was determined. Lyophilization of 9- to 12-hr cells which had been suspended in 5% sodium glutamate plus 0.5% gum tragacanth, frozen in liquid nitrogen vapor, and dried 4 to 5 hr with the ampoules exposed to room temperature resulted in survival of 64.6% of the original cells. After storage of these lyophilized preparations for 6 months at room temperature, 10.5% of the original cells were still viable. PMID:6031431

  18. The self limiting effect of hydrogen cluster in gas jet under liquid nitrogen temperature

    International Nuclear Information System (INIS)

    Han Jifeng; Yang Chaowen; Miao Jingwei; Fu Pengtao; Luo Xiaobing; Shi Miangong

    2010-01-01

    The generation of hydrogen clusters in gas jet is tested using the Rayleigh scattering method under liquid nitrogen temperature of 79 K. The self limiting effect of hydrogen cluster is studied and it is found that the cluster formation is greatly affected by the number of expanded molecules. The well designed liquid nitrogen cold trap ensured that the hydrogen cluster would keep maximum size for maximum 15 ms during one gas jet. The scattered light intensity exhibits a power scaling on the backing pressure ranging from 5 to 48 bar with the power value of 4.1.

  19. Pressure-volume-temperature gauging method experiment using liquid nitrogen under microgravity condition of parabolic flight

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Man Su; Park, Hana; Yoo, Don Gyu; Jeong, Sang Kwon [Cryogenic Engineering Laboratory, Department of Mechanical Engineering, KAIST, Daejeon (Korea, Republic of); Jung, Young Suk [Launcher Systems Development Team, Korea Aerospace Research Institute, Daejeon (Korea, Republic of)

    2014-06-15

    Measuring an exact amount of remaining cryogenic liquid propellant under microgravity condition is one of the important issues of rocket vehicle. A Pressure-Volume-Temperature (PVT) gauging method is attractive due to its minimal additional hardware and simple gauging process. In this paper, PVT gauging method using liquid nitrogen is investigated under microgravity condition with parabolic flight. A 9.2 litre metal cryogenic liquid storage tank containing approximately 30% of liquid nitrogen is pressurized by ambient temperature helium gas. During microgravity condition, the inside of the liquid tank becomes near-isothermal condition within 1 K difference indicated by 6 silicon diode sensors vertically distributed in the middle of the liquid tank. Helium injection with higher mass flow rate after 10 seconds of the waiting time results in successful measurements of helium partial pressure in the tank. Average liquid volume measurement error is within 11% of the whole liquid tank volume and standard deviation of errors is 11.9. As a result, the applicability of PVT gauging method to liquid.

  20. Pressure-volume-temperature gauging method experiment using liquid nitrogen under microgravity condition of parabolic flight

    International Nuclear Information System (INIS)

    Seo, Man Su; Park, Hana; Yoo, Don Gyu; Jeong, Sang Kwon; Jung, Young Suk

    2014-01-01

    Measuring an exact amount of remaining cryogenic liquid propellant under microgravity condition is one of the important issues of rocket vehicle. A Pressure-Volume-Temperature (PVT) gauging method is attractive due to its minimal additional hardware and simple gauging process. In this paper, PVT gauging method using liquid nitrogen is investigated under microgravity condition with parabolic flight. A 9.2 litre metal cryogenic liquid storage tank containing approximately 30% of liquid nitrogen is pressurized by ambient temperature helium gas. During microgravity condition, the inside of the liquid tank becomes near-isothermal condition within 1 K difference indicated by 6 silicon diode sensors vertically distributed in the middle of the liquid tank. Helium injection with higher mass flow rate after 10 seconds of the waiting time results in successful measurements of helium partial pressure in the tank. Average liquid volume measurement error is within 11% of the whole liquid tank volume and standard deviation of errors is 11.9. As a result, the applicability of PVT gauging method to liquid

  1. Study on boiling heat transfer of subcooled flow under oscillatory flow condition

    International Nuclear Information System (INIS)

    Ohtake, Hiroyasu; Yamazaki, Satoshi; Koizumi, Yasuo

    2004-01-01

    The Onset of Nucleate Boiling, the point of Net Vapor Generation and Critical Heat Flux on subcooled flow boiling under oscillatory flow, focusing on liquid velocity, amplitude and frequency of oscillatory flow were investigated experimentally and analytically. Experiments were conducted using a copper thin-film and subcooled water in a range of the liquid velocity from 0.27 to 4.07 m/s at 0.10MPa. The liquid subcooling was 20K. Frequency of oscillatory flow was 2 and 4 Hz, respectively; amplitude of oscillatory flow was 25 and 50% in a ratio of main flow rate, respectively. Temperatures at Onset of Nuclear Boiling and Critical Heat Flux obtained in the experiments decreased with the oscillatory flow. The decrease of liquid velocity by oscillatory flow caused the ONB and the CHF to decrease. On the other hand, heat flux at Net Vapor Generation decreased with oscillatory flow; the increase of liquid velocity by oscillatory flow caused the NVG to decrease. (author)

  2. Simulation methods of rocket fuel refrigerating with liquid nitrogen and intermediate heat carrier

    Directory of Open Access Journals (Sweden)

    O. E. Denisov

    2014-01-01

    Full Text Available Temperature preparation of liquid propellant components (LPC before fueling the tanks of rocket and space technology is the one of the operations performed by ground technological complexes on cosmodromes. Refrigeration of high-boiling LPC is needed to increase its density and to create cold reserve for compensation of heat flows existing during fueling and prelaunch operations of space rockets.The method and results of simulation of LPC refrigeration in the recuperative heat exchangers with heat carrier which is refrigerated by-turn with liquid nitrogen sparging. The refrigerating system consists of two tanks (for the chilled coolant and LPC, LPC and heat carrier circulation loops with heat exchanger and system of heat carrier refrigeration in its tank with bubbler. Application of intermediate heat carrier between LPC and liquid nitrogen allows to avoid LPC crystallization on cold surfaces of the heat exchanger.Simulation of such systems performance is necessary to determine its basic design and functional parameters ensuring effective refrigerating of liquid propellant components, time and the amount of liquid nitrogen spent on refrigeration operation. Creating a simulator is quite complicated because of the need to take into consideration many different heat exchange processes occurring in the system. Also, to determine the influence of various parameters on occurring processes it is necessary to take into consideration the dependence of all heat exchange parameters on each other: heat emission coefficients, heat transfer coefficients, heat flow amounts, etc.The paper offers an overview of 10 references to foreign and Russian publications on separate issues and processes occurring in liquids refrigerating, including LPC refrigeration with liquid nitrogen. Concluded the need to define the LPC refrigerating conditions to minimize cost of liquid nitrogen. The experimental data presented in these publications is conformed with the application of

  3. Liquid nitrogen-cooled diamond-wire concrete cutting. Innovative technology summary report

    International Nuclear Information System (INIS)

    1998-12-01

    Liquid nitrogen-cooled diamond-wire concrete cutting can be used to cut through thick concrete walls, floors, and structures without using water to cool the cutting wire. The diamond wire is cooled with liquid nitrogen in a 0.9-m (3-ft) long by 7.6-cm (3-in.) diameter pipe housing. The nitrogen evaporates, so no contaminated liquid waste is generated. Other than the use of liquid nitrogen, the system is a conventional diamond-wire saw assembly with remote hydraulic controls. Setup of the hydraulic-powered drive wheel and the diamond wire for cutting requires a relatively short period of time using people with minimal training. Concrete dust generated during the cutting is considerable and requires control. The production rate of this improved technology is 0.78 m 2 /hr (8.4 ft 2 /hr). The production rates of traditional (baseline) water-cooled diamond-wire cutting and circular saw cutting technologies are 1.11 m 2 /hr (12 ft 2 /hr), and 0.45 m 2 /hr (4.8 ft 2 /hr), respectively. The liquid nitrogen-cooled system costs 189% more than conventional diamond-wire cutting if contaminated liquid wastes collection, treatment, and disposal are not accounted for with the baseline. The new technology was 310% more costly than a conventional diamond circular saw, under the conditions of this demonstration (no wastewater control). For cutting a 0.9-m x 3.7-m (3-ft x 12-ft) wall, the improved technology costs $17,000, while baseline diamond-wire cutting would cost $9,000 and baseline circular-saw cutting would cost $5,500. The improved system may cost less than the baseline technologies or may be comparable in cost if wastewater control is included

  4. Liquid nitrogen-cooled diamond-wire concrete cutting. Innovative technology summary report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-12-01

    Liquid nitrogen-cooled diamond-wire concrete cutting can be used to cut through thick concrete walls, floors, and structures without using water to cool the cutting wire. The diamond wire is cooled with liquid nitrogen in a 0.9-m (3-ft) long by 7.6-cm (3-in.) diameter pipe housing. The nitrogen evaporates, so no contaminated liquid waste is generated. Other than the use of liquid nitrogen, the system is a conventional diamond-wire saw assembly with remote hydraulic controls. Setup of the hydraulic-powered drive wheel and the diamond wire for cutting requires a relatively short period of time using people with minimal training. Concrete dust generated during the cutting is considerable and requires control. The production rate of this improved technology is 0.78 m{sup 2}/hr (8.4 ft{sup 2}/hr). The production rates of traditional (baseline) water-cooled diamond-wire cutting and circular saw cutting technologies are 1.11 m{sup 2}/hr (12 ft{sup 2}/hr), and 0.45 m{sup 2}/hr (4.8 ft{sup 2}/hr), respectively. The liquid nitrogen-cooled system costs 189% more than conventional diamond-wire cutting if contaminated liquid wastes collection, treatment, and disposal are not accounted for with the baseline. The new technology was 310% more costly than a conventional diamond circular saw, under the conditions of this demonstration (no wastewater control). For cutting a 0.9-m x 3.7-m (3-ft x 12-ft) wall, the improved technology costs $17,000, while baseline diamond-wire cutting would cost $9,000 and baseline circular-saw cutting would cost $5,500. The improved system may cost less than the baseline technologies or may be comparable in cost if wastewater control is included.

  5. Theoretical prediction method of subcooled flow boiling CHF

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Young Min; Chang, Soon Heung [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1999-12-31

    A theoretical critical heat flux (CHF ) model, based on lateral bubble coalescence on the heated wall, is proposed to predict the subcooled flow boiling CHF in a uniformly heated vertical tube. The model is based on the concept that a single layer of bubbles contacted to the heated wall prevents a bulk liquid from reaching the wall at near CHF condition. Comparisons between the model predictions and experimental data result in satisfactory agreement within less than 9.73% root-mean-square error by the appropriate choice of the critical void fraction in the bubbly layer. The present model shows comparable performance with the CHF look-up table of Groeneveld et al.. 28 refs., 11 figs., 1 tab. (Author)

  6. Assessment of interfacial heat transfer models under subcooled flow boiling

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, Guilherme B.; Braz Filho, Francisco A., E-mail: gbribeiro@ieav.cta.br, E-mail: fbraz@ieav.cta.br [Instituto de Estudos Avançados (DCTA/IEAv), São José dos Campos, SP (Brazil). Div. de Energia Nuclear

    2017-07-01

    The present study concerns a detailed analysis of subcooled flow boiling characteristics under high pressure systems using a two-fluid Eulerian approach provided by a Computational Fluid Dynamics (CFD) solver. For this purpose, a vertical heated pipe made of stainless steel with an internal diameter of 15.4 mm was considered as the modeled domain. An uniform heat flux of 570 kW/m2 and saturation pressure of 4.5 MPa were applied to the channel wall, whereas water mass flux of 900 kg/m2s was considered for all simulation cases. The model was validated against a set of experimental data and results have indicated a promising use of CFD technique for the estimation of wall temperature, the liquid bulk temperature and the location of the departure of nucleate boiling. Different sub-models of interfacial heat transfer coefficient were applied and compared, allowing a better prediction of void fraction along the heated channel. (author)

  7. Theoretical prediction method of subcooled flow boiling CHF

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Young Min; Chang, Soon Heung [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1998-12-31

    A theoretical critical heat flux (CHF ) model, based on lateral bubble coalescence on the heated wall, is proposed to predict the subcooled flow boiling CHF in a uniformly heated vertical tube. The model is based on the concept that a single layer of bubbles contacted to the heated wall prevents a bulk liquid from reaching the wall at near CHF condition. Comparisons between the model predictions and experimental data result in satisfactory agreement within less than 9.73% root-mean-square error by the appropriate choice of the critical void fraction in the bubbly layer. The present model shows comparable performance with the CHF look-up table of Groeneveld et al.. 28 refs., 11 figs., 1 tab. (Author)

  8. Analysis of subcooled boiling with the two-fluid particle interaction method

    International Nuclear Information System (INIS)

    Shirakawa, Noriyuki; Horie, Hideki; Yamamoto, Yuichi; Tsunoyama, Shigeaki

    2003-01-01

    A particle interaction method called MPS (the Moving Particle Semi-implicit method), which formulates the differential operators in Navier-Stokes' equation as interactions between particles characterized by a kernel function, has been developed in recent years. We have extended this method to a two-fluid system with a potential-type surface tension in order to analyze the two-phase flow without experimental correlation. This extended method (Two-Fluid MPS: TF-MPS) was successfully applied to a subcooled boiling experiment. The most important element in any effective subcooled boiling model is to be able to accurately calculate where significant void fraction appears, that is, the location of the void departure point. The location of the initial void ejection into the subcooled liquid core can be determined fairly well experimentally and conventionally is given in terms of a critical subcooling. We investigated the relation between Stanton and Peclet numbers at the void departure point in the calculated results with TF-MPS method, varying the inlet water velocity to change Peclet number. (author)

  9. Use of liquid nitrogen and albendazole in successfully treating cutaneous larva migrans

    International Nuclear Information System (INIS)

    Kapadia, N.; Farooqui, M.; Borhany, T.

    2013-01-01

    Objective: To determine the efficacy of combination treatment of Albendazole along with liquid nitrogen in cutaneous larva migrans. Study Design: Quasi-experimental study. Place and Duration of Study: Abbasi Shaheed Hospital and The Aga Khan Hospital, Karachi, from December 2008 to December 2010. Methodology: Eighteen cases of cutaneous larva migrans were collected and divided into two groups. Group-A was administered oral Albendazole 400 mg once per day along with topical steroid and oral cetrizine 10 mg once at night for 7 days. Group-B also received oral Albendazole 400 mg once per day along with cetrizine 10 mg once at night but they also received single application of liquid nitrogen to freeze the larva. Results: It was found that in Group-A only 2 out of 9 (22%) showed improvement whereas 78% had to be given liquid nitrogen cryotherapy 3 - 7 days after Albendazole to prevent migration of larva. In Group-B, the improvement was 100% and all 9 patients were successfully treated. Conclusion: Use of liquid nitrogen along with oral anti-helminths is very effective in treating cutaneous larva migrans than Albendazole alone. (author)

  10. Microbial contamination of embryos and semen during long term banking in liquid nitrogen.

    Science.gov (United States)

    Bielanski, A; Bergeron, H; Lau, P C K; Devenish, J

    2003-04-01

    We report on microbial contamination of embryos and semen cryopreserved in sealed plastic straws and stored for 6-35 years in liquid nitrogen. There were 32 bacterial and 1 fungal species identified from randomly drawn liquid nitrogen, frozen semen, and embryos samples stored in 8 commercial and 8 research facility liquid nitrogen (LN) tanks. The identified bacteria represented commensal or environmental microorganisms and some, such as Escherichia coli, were potential or opportunistic pathogens for humans and animals. Stenotrophomonas maltophilia was the most common contaminant identified from the samples and was further shown to significantly suppress fertilization and embryonic development in vitro. Analysis of the strains by pulsed field gel electrophoresis revealed restriction patterns with no relatedness indicating that there was no apparent cross-contamination of S. maltophilia strains between the germplasm and liquid nitrogen samples. In addition, no transmission of bovine viral diarrhea virus (BVDV) and bovine herpesvirus-1 (BHV-1) from infected semen and embryos straws to clean germplasm stored in the same LN tanks or LN was detected.

  11. Non liquid nitrogen-based-method for isolation of DNA from ...

    African Journals Online (AJOL)

    A simple, efficient, reliable and cost-effective method for isolation of total genomic DNA from fungi, suitable for polymerase chain reaction (PCR) amplification and other molecular applications was described. The main advantages of the method are: (1) does not require the use of liquid nitrogen for preparation of fungi DNA; ...

  12. Open loop, auto reversing liquid nitrogen circulation thermal system for thermo vacuum chamber

    International Nuclear Information System (INIS)

    Naidu, M C A; Nolakha, Dinesh; Saharkar, B S; Kavani, K M; Patel, D R

    2012-01-01

    In a thermo vacuum chamber, attaining and controlling low and high temperatures (-100 Deg. C to +120 Deg. C) is a very important task. This paper describes the development of 'Open loop, auto reversing liquid nitrogen based thermal system'. System specifications, features, open loop auto reversing system, liquid nitrogen flow paths etc. are discussed in this paper. This thermal system consists of solenoid operated cryogenic valves, double embossed thermal plate (shroud), heating elements, temperature sensors and PLC. Bulky items like blowers, heating chambers, liquid nitrogen injection chambers, huge pipe lines and valves were not used. This entire thermal system is very simple to operate and PLC based, fully auto system with auto tuned to given set temperatures. This system requires a very nominal amount of liquid nitrogen (approx. 80 liters / hour) while conducting thermo vacuum tests. This system was integrated to 1.2m dia thermo vacuum chamber, as a part of its augmentation, to conduct extreme temperature cycling tests on passive antenna reflectors of satellites.

  13. Preservation of Meloidogyne hapla and M. chitwoodi in liquid nitrogen: Differences in response between populations

    NARCIS (Netherlands)

    Beek, van der J.G.; Veldhuis, W.B.J.; ZijIstra, C.; Silfhout, van C.H.

    1996-01-01

    A procedure for long-term preservation of gennplasm of Meloidogyne hapla and M. chitwoodi in liquid nitrogen is described, including a pretrearrnenr with 10% ethanediol for 2 h at room temperature and 40 % ethanecliol for 45 min on ice. Survival rates ranged from 45 to 98 % with an average of 75 %.

  14. Recovery time of high temperature superconducting tapes exposed in liquid nitrogen

    International Nuclear Information System (INIS)

    Sheng, Jie; Zeng, Weina; Yao, Zhihao; Zhao, Anfeng; Hu, Daoyu; Hong, Zhiyong

    2016-01-01

    Highlights: • A novel method based on a sequence of AC pulses is presented. • Liquid nitrogen temperature is used as criterion to judge whether the sample has recovered. • Recovery time of some tape doesn't increase with the amplitude of fault current. • This phenomenon is caused by boiling heat transfer process of liquid nitrogen. • This phenomenon can be used in optimizing both the limiting rate and reclosing system. - Abstract: The recovery time is a crucial parameter to high temperature superconducting tapes, especially in power applications. The cooperation between the reclosing device and the superconducting facilities mostly relies on the recovery time of the superconducting tapes. In this paper, a novel method is presented to measure the recovery time of several different superconducting samples. In this method criterion used to judge whether the sample has recovered is the liquid nitrogen temperature, instead of the critical temperature. An interesting phenomenon is observed during the testing of superconducting samples exposed in the liquid nitrogen. Theoretical explanations of this phenomenon are presented from the aspect of heat transfer. Optimization strategy of recovery characteristics based on this phenomenon is also briefly discussed.

  15. Use of liquid nitrogen and albendazole in successfully treating cutaneous larva migrans.

    Science.gov (United States)

    Kapadia, Naseema; Borhany, Tasneem; Farooqui, Maria

    2013-05-01

    To determine the efficacy of combination treatment of Albendazole along with liquid nitrogen in cutaneous larva migrans. Quasi-experimental study. Abbasi Shaheed Hospital and The Aga Khan Hospital, Karachi, from December 2008 to December 2010. Eighteen cases of cutaneous larva migrans were collected and divided into two groups. Group-A was administered oral Albendazole 400 mg once per day along with topical steroid and oral cetrizine 10 mg once at night for 7 days. Group-B also received oral Albendazole 400 mg once per day along with cetrizine 10 mg once at night but they also received single application of liquid nitrogen to freeze the larva. It was found that in Group-A only 2 out of 9 (22%) showed improvement whereas 78% had to be given liquid nitrogen cryotherapy 3 - 7 days after Albendazole to prevent migration of larva. In Group-B, the improvement was 100% and all 9 patients were successfully treated. Use of liquid nitrogen along with oral anti-helminths is very effective in treating cutaneous larva migrans than Albendazole alone.

  16. Liquid nitrogen-treated autogenous dentin as bone substitute: an experimental study in a rabbit model.

    Science.gov (United States)

    Atiya, Basim K; Shanmuhasuntharam, Palasuntharam; Huat, Siar; Abdulrazzak, Shurooq; Oon, Ha

    2014-01-01

    Different forms of dentin, including untreated, undemineralized, demineralized, boiled, or mixed with other materials, have been evaluated for efficacy as bone substitutes. However, the effects of application of liquid nitrogen-treated dentin for bone grafting remain unknown. The objective of this study was to chronologically evaluate bone healing following grafting with liquid nitrogen-treated dentin in a rabbit model. Autogenous dentin treated with liquid nitrogen at -196°C for 20 minutes was used. In 16 New Zealand White rabbits, a bone defect (5 mm in diameter) was created in each femur and randomly grafted with either autogenous dentin (experimental group) or autogenous bone grafts (positive control). In another four rabbits (negative control), a similar defect in each femur was left empty. The rabbits were sacrificed at 2, 4, 8, and 12 weeks. Explants of grafted sites were harvested for histologic and histomorphometric analysis. At 2 and 4 weeks in both the experimental and positive control groups, accelerated formation of new bone was observed, which was undergoing remodeling at 8 and 12 weeks. The mean new bone score was higher in the experimental than in the negative control groups, but this was not statistically significant. The present results demonstrated that liquid nitrogen-treated autogenous dentin has both osteoconductive and osteoinductive properties and therefore has potential as a bone substitute.

  17. Dissolved nitrogen in liquid lithium - a problem in fusion reactor chemistry

    International Nuclear Information System (INIS)

    Hubberstey, P.

    1984-01-01

    When dissolved in liquid lithium, nitrogen adopts the role filled by oxygen in liquid sodium systems, reacting readily with stainless steel containment materials to form Li 9 CrN 5 as a surface product; extended reaction leads to pronounced corrosion and embrittlement problems. It also interacts with both carbon and silicon impurities forming Li 2 NCN and Li 5 SiN 3 , respectively; it is inert, however, to oxygen impurity. Although dissolved nitrogen reacts with neither the tritium generated in the breeding process nor the lead added to act as a neutron multiplier, its presence may seriously influence tritium recovery processes since it reacts with and hence may poison the majority of the transition metals (Y,Ti,Zr) presently being considered as tritium getter materials. Its reactivity with these metals forms the basis of the hot trapping technique used to remove dissolved nitrogen from liquid lithium systems; cold trapping is ineffective because of its large solubility even at temperatures just above the melting point of pure lithium (453.6K). Whenever possible, the chemistry of nitrogen dissolved in liquid lithium is rationalised using the thermodynamic concepts and its significance to fusion reactor technology stressed. (author)

  18. Nitrogen Fertilizer Replacement Value of Concentrated Liquid Fraction of Separated Pig Slurry Applied to Grassland

    NARCIS (Netherlands)

    Middelkoop, Van J.C.; Holshof, G.

    2017-01-01

    Seven grassland experiments on sandy and clay soils were performed during a period of 4 years to estimate the nitrogen (N) fertilizer replacement value (NFRV) of concentrated liquid fractions of separated pig slurry (mineral concentrate: MC). The risk of nitrate leaching when applying MC was

  19. Cryopreservation of citrus seed via dehydration followed by immersion in liquid nitrogen

    Science.gov (United States)

    An important method for plant germplasm conservation is offered by a biotechnology-based approach of cryopreservation. Cryopreservation refers to the storage of plant material at ultralow temperatures in liquid nitrogen. A procedure for cryopreservation of polyembryonic seeds was improved for select...

  20. Installation of the liquid nitrogen tank for the external cryogenics system

    CERN Multimedia

    2001-01-01

    The picture shows the installation of the 50000l liquid nitrogen tank in its first position next to the SHL annex of the SX5 building. The tank will be moved to its final position after the completion of the surface tests.

  1. Recovery of valuable nitrogen compounds from agricultural liquid wastes: potential possibilities, bottlenecks and future technological challenges.

    NARCIS (Netherlands)

    Rulkens, W.H.; Klapwijk, A.; Willers, H.C.

    1998-01-01

    Agricultural liquid livestock wastes are an important potential source of valuable nitrogen-containing compounds such as ammonia and proteins. Large volumetric quantities of these wastes are produced in areas with a high livestock production density. Much technological research has been carried out

  2. CFD for subcooled flow boiling: Simulation of DEBORA experiments

    International Nuclear Information System (INIS)

    Krepper, Eckhard; Rzehak, Roland

    2011-01-01

    Highlights: → In the DEBORA subcooled boiling tests using R12 are investigated. → Radial profiles of void fraction, liquid velocity, temperature and bubble sizes at the end of the heated length were measured. → The theoretical and experimental basis of correlations used in the wall boiling model are reviewed. → An assessment of the necessary recalibrations to describe the DEBORA tests is given. → With increased generated vapour the gas fraction profile changes from wall to core peaking, not captured by the present modelling. - Abstract: In this work we investigate the present capabilities of CFD for wall boiling. The computational model used combines the Euler/Euler two-phase flow description with heat flux partitioning. Very similar modelling 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, liquid temperature and bubble size. After reviewing the theoretical and experimental basis of correlations used in the model, give a careful assessment of the necessary recalibrations to describe the DEBORA tests. It is then shown that within a certain range of conditions different tests can be simulated with a single set of model parameters. As the subcooling is decreased and the amount of generated vapour increases the gas fraction profile changes from wall to core peaking. This is a major effect not captured by the present modelling. Some quantitative deviations are assessed as well and directions for further model improvement are outlined.

  3. Experimental research on rock fracture failure characteristics under liquid nitrogen cooling conditions

    Science.gov (United States)

    Gao, Feng; Cai, Chengzheng; Yang, Yugui

    2018-06-01

    As liquid nitrogen is injected into a wellbore as fracturing fluid, it can rapidly absorb heat from warmer rock and generate cryogenic condition in downhole region. This will alter the physical conditions of reservoir rocks and further affect rock failure characteristics. To investigate rock fracture failure characteristics under liquid nitrogen cooling conditions, the fracture features of four types of sandstones and one type of marble were tested on original samples (the sample without any treatment) and cryogenic samples (the samples just taken out from the liquid nitrogen), respectively. The differences between original samples and cryogenic samples in load-displacement curves, fracture toughness, energy evolution and the crack density of ruptured samples were compared and analyzed. The results showed that at elastic deformation stage, cryogenic samples presented less plastic deformation and more obvious brittle failure characteristics than original ones. The average fracture toughness of cryogenic samples was 10.47%-158.33% greater than that of original ones, indicating that the mechanical strength of rocks used were enhanced under cooling conditions. When the samples ruptured, the cryogenic ones were required to absorb more energy and reserve more elastic energy. In general, the fracture degree of cryogenic samples was higher than that of original ones. As the samples were entirely fractured, the crack density of cryogenic samples was about 536.67% at most larger than that of original ones. This indicated that under liquid nitrogen cooling conditions, the stimulation reservoir volume is expected to be improved during fracturing. This work could provide a reference to the research on the mechanical properties and fracture failure of rock during liquid nitrogen fracturing.

  4. Post-thaw sperm characteristics following long-term storage of boar semen in liquid nitrogen.

    Science.gov (United States)

    Fraser, L; Strzeżek, J; Kordan, W

    2014-06-30

    This study investigated the effect of long-term liquid nitrogen storage of semen from individual boars on post-thaw sperm characteristics. Ejaculates, collected from five Polish large white (PLW) and five Polish landrace (PLR) boars, were frozen using a standard cryopreservation protocol. Post-thaw analysis was performed within a week (Period 1) and 42-48 months (Period 2) of semen storage in liquid nitrogen. Post-thaw sperm assessments included total motility, mitochondrial function (JC-1/PI assay), plasma membrane integrity (SYBR-14/PI assay), osmotic resistance test (ORT), lipid peroxidation (LPO) status and DNA fragmentation, analysed by the neutral Comet assay. Individual boar variability within breed and cryostorage periods had significant effects on the analysed parameters of frozen-thawed spermatozoa. Prolonged semen storage in liquid nitrogen (Period 2) induced a marked reduction in post-thaw sperm motility, mitochondrial function and plasma membrane integrity in most of the boars. Post-thaw semen of eight boars exhibited a marked decrease in osmotic resistance of the sperm acrosomal membrane, whereas a significant increase in the sperm cryo-susceptibility to induced LPO and DNA fragmentation was observed only in three boars after long-term semen storage. Additionally, frozen-thawed spermatozoa of PLR boars exhibited significantly lower osmotic resistance of the acrosomal membrane than PLW boars following prolonged semen storage in liquid nitrogen. The results of this study provide evidence of ageing processes in frozen-thawed boar spermatozoa following prolonged cryostorage. It seems that, even though cryopreservation allows long-term semen storage in liquid nitrogen, spermatozoa from individual boars are more susceptible to cryo-induced damage. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Experimental investigation on No-Vent Fill (NVF) process using liquid Nitrogen

    International Nuclear Information System (INIS)

    Kim, Young Cheol; Seo, Man Su; Yoo, Dong Gyu; Jeong, Sang Kwon

    2014-01-01

    For a long-term space mission, filling process of cryogenic liquid propellant is operated on a space vehicle in space. A vent process during transfer and filling of cryogenic propellant is needed to maintain the fuel tank pressure at a safe level due to its volatile characteristic. It is possible that both liquid and vapor phases of the cryogenic propellant are released simultaneously to outer space when the vent process occurs under low gravity environment. As a result, the existing filling process with venting not only accompanies wasting liquid propellant, but also consumes extra fuel to compensate for the unexpected momentum originated from the vent process. No-Vent Fill (NVF) method, a filling procedure without a venting process of cryogenic liquid propellant, is an attractive technology to perform a long-term space mission. In this paper, the preliminary experimental results of the NVF process are described. The experimental set-up consists of a 9-liter cryogenic liquid receiver tank and a supply tank. Liquid nitrogen (LN2) is used to simulate the behavior of cryogenic propellant. The whole situation in the receiver tank during NVF is monitored. The major experimental parameter in the experiment is the mass flow rate of the liquid nitrogen. The experimental results demonstrate that as the mass flow rate is increased, NVF process is conducted successfully. The quality and the inlet temperature of the injected LN2 are affected by the mass flow rate. These parameters determine success of NVF.

  6. Nitrogen tetroxide vapor scrubber using a recirculating liquid

    Science.gov (United States)

    Reisert, T. D.

    1978-01-01

    Scrubbers required to reduce N2O4 contamination of nitrogen vent gas streams to a safe level to preclude health hazard to personnel and to preclude adverse environmental effects were developed. The scrubber principle involved is to absorb and neutralize the N2O4 component in a closed circuit circulating water/chemical solution in a vertical counter-flow, packed-tower configuration. The operational and performance test requirements for the scrubbers consist of demonstrating that the exit gas contamination level from the scrubbers does not exceed 150 ppm oxidizer under any flow conditions up to 400 scfm with inlet concentrations of up to 100,000 ppm oxidizer. Several problems were encountered during the performance testing that led to a series of investigations and supplementary testing. It was finally necessary to change the scrubber liquors in oxidizer scrubber to successfully achieve performance requirements. The scrubbers, the test configuration, and the various tests performed are described.

  7. Measurement of the neutron and gamma-ray spectra originating from a 14-MeV neutron source in liquid nitrogen and liquid air

    International Nuclear Information System (INIS)

    Broecker, B.; Clausen, K.; Schneider-Kuehnle, P.; Weinert, M.

    1975-01-01

    An experiment to measure the radiation transport originating from a 14-MeV neutron source in liquid nitrogen and liquid air is presented. Neutron and gamma-ray spectra were measured with a proton-recoil NE 213 scintillator and with four spherical proportional counters in a tank filled with liquid nitrogen or liquid air. The neutron spectra cover the energy range of 20 keV to 18 MeV. The source-detector separation varies in the liquid medium between 60 and 240 cm. The experimental setup is briefly described and the errors are estimated. (2 tables, 9 figures) (auth)

  8. Effect of carbon and silicon on nitrogen solubility in liquid chromium and iron-chromium alloys

    International Nuclear Information System (INIS)

    Khyakkinen, V.I.; Bezobrazov, S.V.

    1986-01-01

    The study is aimed at specifying the role of carbon and silicon in high-chromium melts nitridation processes. It is shown that in high-chromium melts of the Cr-Fe-C system the nitrogen solubility is reduced with the growth of carbon content and in the chromium concentration range of 70-100% at 1873 K and P N 2 =0.1 MPa it is described by the lg[%N] Cr-Fe-C =lg[%N] cr-fe -0.098[%C] equation. While decreasing the temperature the nitrogen solubility in alloys is increased. Silicon essentially decreases the nitrogen solubility in liquid chromium. For the 0-10% silicon concentration range the relation between the equilibrium content of nitrogen and silicon at 1873 K and P N 2 =0.1 MPa is described by the straight line equation [%N] Cr-Si =6.1-0.338 [%Si

  9. Liquid nitrogen enhancement of partially annealed fission tracks in glass

    International Nuclear Information System (INIS)

    Pilione, L.J.; Gold, D.P.

    1976-01-01

    It is known that the number density of fission tracks in solids is reduced if the sample is heated before chemical etching, and the effect of annealing must be allowed for before an age can be assigned to the sample. The extent of annealing can be determined by measuring the reduction of track parameters (diameter and/or length) and comparison with unannealed tracks. Correct ages can be obtained by careful calibration studies of track density reduction against track diameter or length reduction at different annealing temperatures and times. For crystallised minerals, however, the resulting correction techniques are not generally valid. In the experimental work described glass samples were partially annealed and then immersed in liquid N 2 for various periods, and it was shown that the properties of the glass and the track parameters could be altered so as to observe tracks that would normally be erased by annealing. The results of track density measurements against liquid N 2 immersion times are shown graphically. A gain of about 40% was achieved after 760 hours immersion time. The size of the tracks was not noticeably affected by the immersion. It was thought that thermal shock might be the cause of the track enhancement, but it was found that repeated immersion for about 2 hours did not lead to an increase in track density. Other studies suggest that the mechanism that erases the tracks through annealing may be partially reversed when the temperature of the sample is significantly lowered for a sufficient length of time. Further work is under way to find whether or not the process of enhancement is a reversal of the annealing process. Similar enhancement effects using liquid N 2 have been observed for d-particle tracks in polycarbonate detectors. (U.K.)

  10. Nitrogen losses and chemical parameters during co-composting of solid wastes and liquid pig manure.

    Science.gov (United States)

    Vázquez, M A; de la Varga, D; Plana, R; Soto, M

    2017-07-04

    The aim of this research was to study nitrogen losses during the treatment of the liquid fraction (LF) of pig manure by co-composting and to establish the best conditions for compost production with higher nitrogen and low heavy metal contents. Windrows were constituted with the solid fraction (SF) of pig manure, different organic waste (SF of pig manure, sawdust and grape bagasse) as co-substrate and Populus spp. wood chips as bulking material and watered intensely with the LF. Results show that nitrogen losses ranged from 30% to 66% of initial nitrogen and were mainly governed by substrate to bulking mass ratio and liquid fraction to substrate (LF/S) ratio, and only secondarily by operational parameters. Nitrogen losses decreased from 55-65% at low LF/S ratios (1.7-1.9 m 3 /t total solids (TS)) to 30-39% at high LF/S ratios (4.4-4.7 m 3 /t TS). Therefore, integrating the LF in the composting process at high LF/S ratios favoured nitrogen recovery and conservation. Nitrogen in the fine fraction (ranging from 27% to 48% of initial nitrogen) was governed by operational parameters, namely pH and temperature. Final compost showed low content in most heavy metals, but Zn was higher than the limits for compost use in agriculture. Zn content in the obtained compost varied from 1863 to 3269 mg/kg dm, depending on several factors. The options for obtaining better quality composts from the LF of pig manure are selecting co-substrates with low heavy metal content and using them instead of the SF of pig manure.

  11. Thermodynamic analysis and evaluation of the nitrogen solubility in liquid Nb and Fe-Nb alloys

    International Nuclear Information System (INIS)

    Qiu Caian

    1994-01-01

    Experimental information on the nitrogen solubility in liquid Nb and Fe-Nb alloys has been critically analysed and then utilized to evaluate the thermodynamic properties of the Nb-N and Fe-Nb-N liquid phases on the basis of thermodynamic models of Gibbs energy. A thermodynamic description of the Fe-Nb-N liquid phase was obtained, which has been used to calculate the N solubility in comparison with experimental results. The effect of an addition of Nb on the temperature dependence of the N solubility in liquid Fe has been examined by comparing with the effect of the Cr and V additions. It has been shown that the N solubility in liquid Nb and Fe-Nb alloys under various conditions is well described by the present calculation. (orig.)

  12. Vertical downward subcooled bubbly flow modelling with RELAP5/MOD3.2.2 gamma

    International Nuclear Information System (INIS)

    Ristevski, R.; Parzer, I.; Markov, Z.

    2000-01-01

    The presented paper will consider the correlation for void fraction distribution in the subcooled boiling flow regime of downward liquid flow at low velocities. More specifically, it will focus on the choice of the most appropriate heat and mass transfer correlation. The experimental findings and theoretical consideration of these processes and phenomena will be compared with RELAP5/MOD3.2.2 Gamma predictions. (author)

  13. Automatic filling of liquid nitrogen traps auxiliary safety devices of a pumping unit

    International Nuclear Information System (INIS)

    Chatel, S.

    1969-01-01

    The liquid nitrogen traps in our laboratories are generally filled at fixed time intervals, the supply being cut when the liquid flowing through the overflow pipe acts on a lever to which is fixed a small cup fitted with a hole which allows the water of condensation to escape. This system is reliable. After a certain time however, the escape hole blocks up, water accumulates and the lever arm no longer works properly. Furthermore the duration of any cuts in the current, is added to the fixed time intervals, and in this case there can be a lack of liquid nitrogen for several hours after the current has been restored. The device described here avoids these problems. A stainless steel tube containing a copper wire passes into the trap and is immersed in the nitrogen which boils at its tip. A mercury manometer with concentric reservoirs, or an oil manometer, acting on two micro switches through a floater, records the pressure corresponding to the difference in level and controls the filling operation. If there is a lack of nitrogen, a valve can be closed by means of a falling weight, or a diffusion pump can be cut off; one time switch and at least two relays are required. One single relay can be used to control, the supply of several similar traps placed in series [fr

  14. Application of Sub-cooled Boiling Model to Thermal-hydraulic Analysis Inside a CANDU-6 Fuel Channel

    International Nuclear Information System (INIS)

    Kim, Man Woong; Lee, Sang Kyu; Kim, Hyun Koon; Yoo, Kun Joong; Kang, Hyoung Chul; Yoo, Seong Yeon

    2007-01-01

    Forced convection nucleate boiling is encountered in heat exchangers during normal and non-nominal modes of operation in pressurized water or boiling water reactors (PWRs or BWRs). If the wall temperature of the piping is higher than the saturation temperature of the nearby liquid, nucleate boiling occurs. In this regime, bubbles are formed at the wall. Their growth is promoted by the wall superheat (the difference between the wall and saturation temperatures), and they depart from the wall as a result of gravitational and liquid inertia forces. If the bulk liquid is subcooled, condensation at the bubble-liquid interface takes place and the bubble may collapse. This convection nucleate boiling is called as a sub-cooled nucleate boiling. As for the fuel channel of a CANDU 6 reactor, forced convection nucleate boiling models for flows along fuel elements enclosed inside typical CANDU-6 fuel channel has encountered difficulties due to the modeling of local effects along the horizontal channel. Therefore, the subcooled nucleate boiling has been modeled through temperature driven boiling heat and mass transfer, using a model developed at Rensselaer Polytechnic Institute. The objectives of this study are: (i) to investigate a proposed sub-cooled boiling model developed at Rensselaer Polytechnic Institute and (ii) to apply against a experiment and (iii) to predict local distributions of flow fields for the actual fuel channel geometries of CANDU-6 reactors. The numerical implementation is conducted using by the FLUENT 6.2 CFD computer code

  15. Subcooled Pool Boiling from Two Tubes of 6 Degree Included Angle in Vertical Alignment

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Myeong-Gie [Andong National University, Andong (Korea, Republic of)

    2015-05-15

    One of the major issues in the design of a heat exchanger is the heat transfer in a tube bundle. The passive condensation heat exchanger (PCHX) adopted in APR+ has U-type tube. The PCHX is submerged in the passive condensation cooling tank (PCCT). The heat exchanging tubes are in vertical alignment and inclined at 3 degrees to prevent water hammer as shown in Fig. 1. For the cases, the upper tube is affected by the lower tube. Therefore, the results for a single tube are not applicable to the design of the PCHX. However, the passive heat exchangers are submerged in the subcooled water under atmospheric pressure. The water temperature in the PCCT rises according to the PAFS actuation and reaches the saturation temperature after more than 2.5 hours. Since this period is very important to maintain reactor integrity, the exact evaluation of heat transfer on the tube bundle is indispensable. Although an experimental study on both subcooled and saturated pool boiling of water was performed to obtain local heat transfer coefficients on a 3 degree inclined tube at atmospheric pressure by Kang, no previous results were treating the bundle effect in the subcooled liquid. The heat transfer on the upper tube is enhanced compared with the single tube. The enhancement of the heat transfer on the upper tube is estimated by the bundle effect ( h{sub r} ). It is defined as the ratio of the heat transfer coefficient ( h{sub b} ) for an upper tube in a bundle with lower tubes activated to that for the same tube activated alone in the bundle. The upper tube within a tube bundle can significantly increase nucleated boiling heat transfer compared to the lower tubes at moderate heat fluxes. Summarizing the published results, it is still necessary to identify effects of liquid subcooling on inclined tubes for application to the PCHX design. Therefore, the present study is aimed to study the variations of pool boiling heat transfer on a tube bundle having a 6 degree included angle in

  16. Cryopreservation of human sperm: efficacy and use of a new nitrogen-free controlled rate freezer versus liquid nitrogen vapour freezing.

    Science.gov (United States)

    Creemers, E; Nijs, M; Vanheusden, E; Ombelet, W

    2011-12-01

    Preservation of spermatozoa is an important aspect of assisted reproductive medicine. The aim of this study was to investigate the efficacy and use of a recently developed liquid nitrogen and cryogen-free controlled rate freezer and this compared with the classical liquid nitrogen vapour freezing method for the cryopreservation of human spermatozoa. Ten patients entering the IVF programme donated semen samples for the study. Samples were analysed according to the World Health Organization guidelines. No significant difference in total sperm motility after freeze-thawing between the new technique and classical technique was demonstrated. The advantage of the new freezing technique is that it uses no liquid nitrogen during the freezing process, hence being safer to use and clean room compatible. Investment costs are higher for the apparatus but running costs are only 1% in comparison with classical liquid nitrogen freezing. In conclusion, post-thaw motility of samples frozen with the classical liquid nitrogen vapour technique was comparable with samples frozen with the new nitrogen-free freezing technique. This latter technique can thus be a very useful asset to the sperm cryopreservation laboratory. © 2011 Blackwell Verlag GmbH.

  17. NaK-nitrogen liquid metal MHD converter tests at 30 kw

    Science.gov (United States)

    Cerini, D. J.

    1974-01-01

    The feasibility of electrical power generation with an ambient temperature liquid-metal MHD separator cycle is demonstrated by tests in which a NaK-nitrogen LM-MHD converter was operated at nozzle inlet pressures ranging from 100 to 165 N/sq cm, NaK flow rates from 46 to 72 kg/sec, and nitrogen flow rates from 2.4 to 3.8 kg/sec. The generator was operated as an eight-phase linear induction generator, with two of the eight phases providing magnetic field compensation to minimized electrical end losses at the generator channel inlet and exit.

  18. Development of nuclear thermal hydraulic verification test and evaluation technology; study on 3-dimension measurement of two-phase flow parameters in subcooled boiling flow

    Energy Technology Data Exchange (ETDEWEB)

    Park, Goon Cherl; Kim, Moon Oh; Cho, Hyung Kyoo; Kim, Seong Jin [Seoul National University, Seoul (Korea)

    2002-04-01

    In this study, the experiments were conducted at different levels of inlet subcooling, flow rate and heat flux in a vertical concentric annulus channel located heater at the center with subcooled boiling conditions of atmosphere pressure and superficial velocity under 1.5m/s. The profiles of void fraction, vapor size, vapor frequency, vapor velocity and IAC were measured by 2 sensor conductivity probe in axially 3 points (L/D{sub h}=90.5,80.1,71.4) and those of liquid velocity by pitot tube. Based on the experiment data subcooled boiling models in MARS and multidimensional code, CFX-4.2 were evaluated was verified for analysis ability of these codes in subcooled boiling. 61 refs., 41 figs., 11 tabs. (Author)

  19. Cryosurgical treatment of warts: dimethyl ether and propane versus liquid nitrogen - case report and review of the literature.

    Science.gov (United States)

    Nguyen, Nicholas V; Burkhart, Craig G

    2011-10-01

    For years, dermatologists have relied on cryotherapy with liquid nitrogen as a safe and effective treatment for warts. More recently, several over-the-counter (OTC) wart-freezing therapies have become available. Manufacturers have substituted liquid nitrogen with dimethyl ether and propane (DMEP), and marketed these new preparations to be safe and effective alternatives to in-office cryotherapy with liquid nitrogen. However, data from in vitro studies and comparative studies in humans refute manufacturers' claims that these products reproduce in-office cryotherapy.

  20. Use of liquid chromatography for measuring atmospheric sulfur dioxide and nitrogen oxide

    Energy Technology Data Exchange (ETDEWEB)

    Benova, E

    1973-02-01

    A literature search to ascertain the applicability of liquid chromatography to the analysis of atmospheric sulfur dioxide and various oxides of nitrogen is reported. Simple or enriched samples can be analyzed. Plastic bags are recommended for preparation of simple samples; and a table of 18 plastic materials, their manufacturers, and pollutants to which they are inert is provided. Enriched samples can be prepared in chromatographic columns by adsorption methods. Tables are provided listing carriers, stationary phase materials, temperatures, carrier liquids (helium or nitrogen), column dimensions, and other data recommended for chromatographic tests of SO/sub 2/ and NOx. Because of its reactivity and tendency to polymerize, sulfur trioxide should be reduced to SO/sub 2/ prior to analysis.

  1. Two-Dimensional Metrology with Flatbed Scanners at Room and Liquid Nitrogen Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Grau Carles, A.; Grau Malonda, A. [CIEMAT. Madrid (Spain)

    2000-07-01

    We study the capability of the commercial flatbed scanner as a measuring instrument of two-coordinate sample both at room and liquid nitrogen temperatures. We describes simple procedure to calibrate the scanner, and the most adequate standard configuration to carry out the measurements. To illustrate the procedure, we measure the relative positions of the conductors in a cross-section of a superconducting magnet of CERN. (Author) 8 refs.

  2. Two-Dimensional Metrology with Flatbed Scanners at Room and Liquid Nitrogen Temperatures

    International Nuclear Information System (INIS)

    Grau Carles, A.; Grau Malonda, A.

    2000-01-01

    We study the capability of the commercial flatbed scanner as a measuring instrument of two-coordinate sample both at room and liquid nitrogen temperatures. We describes simple procedure to calibrate the scanner, and the most adequate standard configuration to carry out the measurements. To illustrate the procedure, we measure the relative positions of the conductors in a cross-section of a superconducting magnet of CERN. (Author) 8 refs

  3. A liquid-nitrogen monitor for lithium-drifted germanium detectors

    International Nuclear Information System (INIS)

    Andeweg, A.H.

    1977-11-01

    An instrument has been developed that makes use of a load cell to monitor the liquid nitrogen in the Dewar flask of a lithium-drifted germaniun detector. The contents are recorded on a chart recorder, and an alarm is sounded when the previously set content has been reached. A signal switches off the high-voltage power supply 30 minutes after the alarm is triggered. The calibration of the load-cell monitor is described in an appendix [af

  4. Comparison between mechanical freezer and conventional freezing using liquid nitrogen in normozoospermia.

    Science.gov (United States)

    Rahana, A R; Ng, S P; Leong, C F; Rahimah, M D

    2011-10-01

    This study evaluated the effect of human semen cryopreservation using an ultra-low temperature technique with a mechanical freezer at -85°C as an alternative method to the conventional liquid nitrogen technique at -196°C. This was a prospective experimental study conducted in the Medically Assisted Conception unit, Department of Obstetrics and Gynaecology, National University Hospital, Malaysia from January 1, 2006 to April 30, 2007. All normozoospermic semen samples were included in the study. The concentration, motility and percentage of intact DNA of each semen sample were assessed before and after freezing and thawing on Days 7 and 30 post freezing. Sperm cryopreservation at -85°C was comparable to the conventional liquid nitrogen technique for a period of up to 30 days in a normozoospermic sample. There was no statistical difference in concentration (Day 7 p-value is 0.1, Day 30 p-value is 0.2), motility (Day 7 p-value is 0.9, Day 30 p-value is 0.5) and proportion of intact DNA (Day 7 p-value is 0.1, Day 30 p-value is 0.2) between the ultra-low temperature technique and conventional liquid nitrogen cryopreservation at Days 7 and 30 post thawing. This study clearly demonstrates that short-term storage of sperm at -85°C could be a viable alternative to conventional liquid nitrogen cryopreservation at -196°C due to their comparable post-thaw results.

  5. Hyperprolinemic larvae of the drosophilid fly, Chymomyza costata, survive cryopreservation in liquid nitrogen.

    Science.gov (United States)

    Kostál, Vladimír; Zahradnícková, Helena; Šimek, Petr

    2011-08-09

    The larva of the drosophilid fly, Chymomyza costata, is probably the most complex metazoan organism that can survive submergence in liquid nitrogen (-196 °C) in a fully hydrated state. We examined the associations between the physiological and biochemical parameters of differently acclimated larvae and their freeze tolerance. Entering diapause is an essential and sufficient prerequisite for attaining high levels of survival in liquid nitrogen (23% survival to adult stage), although cold acclimation further improves this capacity (62% survival). Profiling of 61 different metabolites identified proline as a prominent compound whose concentration increased from 20 to 147 mM during diapause transition and subsequent cold acclimation. This study provides direct evidence for the essential role of proline in high freeze tolerance. We increased the levels of proline in the larval tissues by feeding larvae proline-augmented diets and found that this simple treatment dramatically improved their freeze tolerance. Cell and tissue survival following exposure to liquid nitrogen was evident in proline-fed nondiapause larvae, and survival to adult stage increased from 0% to 36% in proline-fed diapause-destined larvae. A significant statistical correlation was found between the whole-body concentration of proline, either natural or artificial, and survival to the adult stage in liquid nitrogen for diapause larvae. Differential scanning calorimetry analysis suggested that high proline levels, in combination with a relatively low content of osmotically active water and freeze dehydration, increased the propensity of the remaining unfrozen water to undergo a glass-like transition (vitrification) and thus facilitated the prevention of cryoinjury.

  6. Surface Quality Improvement of AA6060 Aluminum Extruded Components through Liquid Nitrogen Mold Cooling

    Directory of Open Access Journals (Sweden)

    Andrea Francesco Ciuffini

    2018-06-01

    Full Text Available 6xxx aluminum alloys are suitable for the realization of both structural applications and architectural decorative elements, thanks to the combination of high corrosion resistance and good surface finish. In areas where the aesthetic aspects are fundamental, further improvements in surface quality are significant. The cooling of the extrusion mold via internal liquid nitrogen fluxes is emerging as an important innovation in aluminum extrusion. Nowadays, this innovation is providing a large-scale solution to obtain high quality surface finishes in extruded aluminum semi-finished products. These results are also coupled to a significant increase in productivity. The aim of the work is to compare the surface quality of both cooled liquid nitrogen molds and classically extruded products. In this work, adhesion phenomena, occurring during the extrusion between the mold and the flowing material, have been detected as the main causes of the presence of surface defects. The analysis also highlighted a strong increase in the surface quality whenever the extrusion mold was cooled with liquid nitrogen fluxes. This improvement has further been confirmed by an analysis performed on the finished products, after painting and chromium plating. This work on the AA6060 alloy has moreover proceeded to roughness measurements and metallographic analyses, to investigate the eventual occurrence of other possible benefits stemming from this new extrusion mold cooling technology.

  7. A model of freezing foods with liquid nitrogen using special functions

    Science.gov (United States)

    Rodríguez Vega, Martín.

    2014-05-01

    A food freezing model is analyzed analytically. The model is based on the heat diffusion equation in the case of cylindrical shaped food frozen by liquid nitrogen; and assuming that the thermal conductivity of the cylindrical food is radially modulated. The model is solved using the Laplace transform method, the Bromwich theorem, and the residue theorem. The temperature profile in the cylindrical food is presented as an infinite series of special functions. All the required computations are performed with computer algebra software, specifically Maple. Using the numeric values of the thermal and geometric parameters for the cylindrical food, as well as the thermal parameters of the liquid nitrogen freezing system, the temporal evolution of the temperature in different regions in the interior of the cylindrical food is presented both analytically and graphically. The duration of the liquid nitrogen freezing process to achieve the specified effect on the cylindrical food is computed. The analytical results are expected to be of importance in food engineering and cooking engineering. As a future research line, the formulation and solution of freezing models with thermal memory is proposed.

  8. Proposal for the award of three contracts for the supply and delivery of liquid nitrogen

    CERN Document Server

    2001-01-01

    This document concerns the award of three contracts for the supply and delivery of liquid nitrogen. A call for tenders (IT-3016/LHC) was sent on 21 September 2001 to 24 firms in eight Member States. By the closing date, CERN had received tenders from four firms in one Member State. For the reasons explained in this document, the Finance Committee is invited to agree to the negotiation of the following three contracts: - a contract with PRAXAIR (FR), the lowest bidder, for the supply of up to 20 000 metric tons of liquid nitrogen over a period of three years for an amount not exceeding 2 486 000 Swiss francs, not subject to revision. - a contract with MESSER FRANCE (FR), the second lowest bidder, for the supply of up to 15 000 metric tons of liquid nitrogen over a period of three years for an amount not exceeding 1 292 542 euros (1 905 000 Swiss francs), not subject to revision. The rate of exchange which has been used is that stipulated in the tender. - a contract with AIR PRODUCTS (FR), the third lowest bidd...

  9. Effect of liquid nitrogen flow rate on solidification of stagnant water in a horizontal tube

    International Nuclear Information System (INIS)

    Ibrahim, S.M.

    1995-01-01

    Five experiments are conducted to study the effect of liquid nitrogen flow rate on the solidification of stagnant water inside a horizontal stainless steel tube of inner diameter 19.6 cm and 12 mm thick. This tube simulates the down-comer of the nuclear reactor ET-R R-1. The apparatus design is mentioned more detail description. The results show that for the first experiment where the liquid nitrogen flow rate is 30 1/hr, the progress of solidification of water has stopped at a diameter of 12 cm. By increasing the flow rate from 30 1/hr to 40,50 and 60 1/hr, the time of freezing the water inside the tube is decreased from 86 to 67 and 60 minutes respectively. By increasing the liquid nitrogen flow rate to 70 1/hr, there is no much effect on the time of frozen. In all experiments, where the solidification is happened, the ice block formed inside the tube is subjected to a pressure of 3 at mg least, and is succeed to withstand this pressure without any leak. 7 figs

  10. Base profile design for high-performance operation of bipolar transistors at liquid-nitrogen temperature

    International Nuclear Information System (INIS)

    Stork, J.M.C.; Harame, D.L.; Meyerson, B.S.; Nguyen, T.N.

    1989-01-01

    The base profile requirements of Si bipolar junction transistors (BJT's) high-performance operation at liquid-nitrogen temperature are examined. Measurements of thin epitaxial-base polysilicon-emitter n-p-n transistors with increasing base doping show the effects of bandgap narrowing, mobility changes, and carrier freezeout. At room temperature the collector current at low injection is proportional to the integrated base charge, independent of the impurity distribution. At temperatures below 150 Κ, however, minority injection is dominated by the peak base doping because of the greater effectiveness of bandgap narrowing. When the peak doping in the base approaches 10 19 cm -3 , the bandgap difference between emitter and base is sufficiently small that the current gain no longer monotonically decreases with lower temperature but instead shows a maximum as low as 180 Κ. The device design window appears limited at the low-current end by increased base-emitter leakage due to tunneling and by resistance control at the high-current end. Using the measured dc characteristics, circuit delay calculations are made to estimate the performance of an ECL ring oscillator at room and liquid-nitrogen temperatures. It is shown that if the base doping can be raised to 10 19 cm -3 while keeping the base thickness constant, the minimum delay at liquid nitrogen can approach the delay of optimized devices at room temperature

  11. Liquid nitrogen cryotherapy for lip mucous membrane venous malformation in infants.

    Science.gov (United States)

    Zhang, Da-Ming; Wang, You-Yuan; Lin, Zhao-Yu; Yang, Zhao-Hui; Chen, Wei-Liang

    2015-03-01

    Lip mucous membrane venous malformations are common benign lesions in infants. This clinical study evaluates the efficacy and safety of liquid nitrogen cryotherapy used to treat this condition. A total of 84 pediatric patients undergoing liquid nitrogen cryotherapy for venous malformations involving the lips were reviewed, with 45 males and 39 females treated. The overall median age at mucous membrane venous malformation diagnosis was 5.6 months (range 2-18 months). The venous malformations involved the vermilion of the lower lip in 44 cases, the vermilion of the upper lip in 31 cases, and both vermilions in 9 cases. No complications due to anesthesia occurred. After a follow-up period of 2-38 months (mean 25 months), 65 lesions (77.4 %) were completely involuted, 14 lesions (16.7 %) were mostly involuted, and 5 lesions (5.9 %) were partially involuted; no lesions showed a minor amount of involution. Liquid nitrogen cryotherapy is an effective, simple, and safe management tool for mucous membrane venous malformations of the lip in infants.

  12. THE PREDICTION OF VOID VOLUME IN SUBCOOLED NUCLEATE POOL BOILING

    Energy Technology Data Exchange (ETDEWEB)

    Duke, E. E. [General Dynamics, San Diego, CA (United States)

    1963-11-15

    A three- step equation was developed that adequately describes the average volume of vapor occurring on a horizontal surface due to nucleate pool boiling of subcooled water. Since extensive bubble frequency data are lacking, the data of others were combined with experimental observations to make predictions of void volume at ambient pressure with various degrees of subcooling. (auth)

  13. Validation of a multidimensional computational fluid dynamics model for subcooled flow boiling analysis

    Energy Technology Data Exchange (ETDEWEB)

    Braz Filho, Francisco A.; Caldeira, Alexandre D.; Borges, Eduardo M., E-mail: fbraz@ieav.cta.b, E-mail: alexdc@ieav.cta.b, E-mail: eduardo@ieav.cta.b [Instituto de Estudos Avancados (IEAv/CTA), Sao Jose dos Campos, SP (Brazil). Div. de Energia Nuclear

    2011-07-01

    In a heated vertical channel, the subcooled flow boiling regime occurs when the bulk fluid temperature is lower than the saturation temperature, but the fluid temperature reaches the saturation point near the channel wall. This phenomenon produces a significant increase in heat flux, limited by the critical heat flux. This study is particularly important to the thermal-hydraulics analysis of pressurized water reactors. The purpose of this work is the validation of a multidimensional model to analyze the subcooled flow boiling comparing the results with experimental data found in literature. The computational fluid dynamics code FLUENT was used with Eulerian multiphase model option. The calculated values of wall temperature in the liquid-solid interface presented an excellent agreement when compared to the experimental data. Void fraction calculations presented satisfactory results in relation to the experimental data in pressures of 15, 30 and 45 bars. (author)

  14. Validation of a multidimensional computational fluid dynamics model for subcooled flow boiling analysis

    International Nuclear Information System (INIS)

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

    2011-01-01

    In a heated vertical channel, the subcooled flow boiling regime occurs when the bulk fluid temperature is lower than the saturation temperature, but the fluid temperature reaches the saturation point near the channel wall. This phenomenon produces a significant increase in heat flux, limited by the critical heat flux. This study is particularly important to the thermal-hydraulics analysis of pressurized water reactors. The purpose of this work is the validation of a multidimensional model to analyze the subcooled flow boiling comparing the results with experimental data found in literature. The computational fluid dynamics code FLUENT was used with Eulerian multiphase model option. The calculated values of wall temperature in the liquid-solid interface presented an excellent agreement when compared to the experimental data. Void fraction calculations presented satisfactory results in relation to the experimental data in pressures of 15, 30 and 45 bars. (author)

  15. Mathematical Model-Based Temperature Preparation of Liquid-Propellant Components Cooled by Liquid Nitrogen in the Heat Exchanger with a Coolant

    Directory of Open Access Journals (Sweden)

    S. K. Pavlov

    2014-01-01

    Full Text Available Before fuelling the tanks of missiles, boosters, and spacecraft with liquid-propellant components (LPC their temperature preparation is needed. The missile-system ground equipment performs this operation during prelaunch processing of space-purpose missiles (SPM. Usually, the fuel cooling is necessary to increase its density and provide heat compensation during prelaunch operation of SPM. The fuel temperature control systems (FTCS using different principles of operation and types of coolants are applied for fuel cooling.To determine parameters of LPC cooling process through the fuel heat exchange in the heat exchanger with coolant, which is cooled by liquid nitrogen upon contact heat exchange in the coolant reservoir, a mathematical model of this process and a design technique are necessary. Both allow us to determine design parameters of the cooling system and the required liquid nitrogen reserve to cool LPC to the appropriate temperature.The article presents an overview of foreign and domestic publications on cooling processes research and implementation using cryogenic products such as liquid nitrogen. The article draws a conclusion that it is necessary to determine the parameters of LPC cooling process through the fuel heat exchange in the heat exchanger with coolant, which is liquid nitrogen-cooled upon contact heat exchange in the coolant reservoir allowing to define rational propellant cooling conditions to the specified temperature.The mathematical model describes the set task on the assumption that a heat exchange between the LPC and the coolant in the heat exchanger and with the environment through the walls of tanks and pipelines of circulation loops is quasi-stationary.The obtained curves allow us to calculate temperature changes of LPC and coolant, cooling time and liquid nitrogen consumption, depending on the process parameters such as a flow rate of liquid nitrogen, initial coolant temperature, pump characteristics, thermal

  16. Modeling of subcooling and solidification of phase change materials

    Science.gov (United States)

    Günther, Eva; Mehling, Harald; Hiebler, Stefan

    2007-12-01

    Phase change materials (PCM) are able to store thermal energy in small temperature intervals very efficiently due to their high latent heat. Particularly high storage capacity is found in salt hydrates. Salt hydrates however often show subcooling, thus inhibiting the release of the stored heat. In the state of the art simulations of PCM, the effect of subcooling is almost always neglected. This is a practicable approach for small subcooling, but it is problematic for subcooling in the order of the driving temperature gradient on unloading the storage. In this paper, we first present a new algorithm to simulate subcooling in a physically proper way. Then, we present a parametric study to demonstrate the main features of the algorithm and a comparison of computed and experimentally obtained data. The new algorithm should be particularly useful in simulating applications with low cooling rates, for example building applications.

  17. Theoretical and experimental investigation of the thermodynamic and kinetic nitrogen absorption by liquid alloys

    Energy Technology Data Exchange (ETDEWEB)

    Grigorenko, G.M.; Pomarin, Yu.M.; Orlovsky, V.Yu. [Natsional' na Akademyiya Nauk Ukrayini, Kiev (Ukraine). E.O. Paton Inst. of Electrical Welding

    1999-07-01

    The work was performed within the framework of the Ukrainian-French program of cooperation in the field of metal of high inclusion and was dedicated to joint fundamental investigation of thermodynamics and kinetics of nitrogen absorption by the Ni-20%Cr liquid alloy. The comparative investigations of kinetic absorption of nitrogen from the gas phase were performed by the method of levitation melting within the temperature range of 1600-1800 C in the atmosphere of pure nitrogen. Using the method of mathematical statistics and experimental Cp values at the different temperatures, the temperature dependence of the equilibrium constant of nitrogen solution reaction in the Ni-20%Cr alloy was obtained (lgK{sub N}=1284/T-1.94). Theoretical and graphical analysis of the experimental data allowed to make the conclusion that the absorption nitrogen process is controlled by the general kinetic equation of the first degree. Using of the aforementioned results the mass transfer factors were calculated with the different temperature and were obtained their mathematical description ({beta}{sub N}{sup Ni-Cr}=-454/T+0.285). (orig.)

  18. Dynamics of liquid nitrogen cooling process of solid surface at wetting contact coefficient

    International Nuclear Information System (INIS)

    Smakulski, P; Pietrowicz, S

    2015-01-01

    Liquid cryogens cooling by direct contact is very often used as a method for decreasing the temperature of electronic devices or equipment i.e. HTS cables. Somehow, cooldown process conducted in that way could not be optimized, because of cryogen pool boiling characteristic and low value of the heat transfer coefficient. One of the possibilities to increase the efficiency of heat transfer, as well as the efficiency of cooling itself, it is to use a spray cooling method. The paper shows dynamics analysis of liquid nitrogen cooling solid surface process. The model of heat transfer for the single droplet of liquid nitrogen, which hits on a flat and smooth surface with respect to the different Weber numbers, is shown. Temperature profiles in calculation domains are presented, as well as the required cooling time. The numerical calculations are performed for different initial and boundary conditions, to study how the wetting contact coefficient is changing, and how it contributed to heat transfer between solid and liquid cryogen. (paper)

  19. Testing of a Spray-bar Thermodynamic Vent System in Liquid Nitrogen

    Science.gov (United States)

    Flachbart, R. H.; Hastings, L. J.; Hedayat, A.; Nelson, S. L.; Tucker, S. P.

    2005-01-01

    To support development of a microgravity pressure control capability for liquid oxygen, thermodynamic vent system (TVS) testing was conducted at Marshall Space Flight Center (MSFC) using liquid nitrogen (LN2) as a LOX simulant. The spray bar TVS hardware used was originally designed by the Boeing Company for testing in liquid hydrogen (LH2). With this concept, a small portion of the tank fluid is passed through a Joule-Thomson (J-T) device, and then through a longitudinal spray bar mixed-heat exchanger in order to cool the bulk fluid. To accommodate the larger mass flow rates associated with LN2, the TVS hardware was modified by replacing the recirculation pump with an LN2 compatible pump and replacing the J-T valve. The primary advantage of the spray-bar configuration is that tank pressure control can be achieved independent of liquid and vapor location, enhancing the applicability of ground test data to microgravity conditions. Performance testing revealed that the spray-bar TVS was effective in controlling tank pressure within a 6.89 kPa band for fill levels of 90%, 50%, and 25%. Tests were also conducted with gaseous helium (GHe) in the ullage. The TVS operated nominally with GHe in the ullage, with performance similar to the tests with gaseous nitrogen (GN2). Testing demonstrated that the spray-bar TVS design was flexible enough for use in two different propellants with minimal hardware modifications.

  20. RELAP5 analysis of subcooled boiling appearance and disappearance in downward flow

    International Nuclear Information System (INIS)

    Ristevski, R.; Parzer, I.; Spasojevic, D.

    1999-01-01

    The presented paper will mainly consider heat and mass transfer phenomenology in the subcooled boiling regime of downward liquid flow at low velocities. More specifically, it will focus on the effects of appearance and disappearance of two-phase flow at low liquid velocities, in the area where gravity force has significant influence. Two among a series of tests performed on a high-pressure circulation loop, installed in Vinca, will be analyzed. The experimental findings and theoretical consideration of these processes and phenomena will be compared with RELAP5/MOD3.2.2 predictions.(author)

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  2. Experimental, Numerical, and Analytical Slosh Dynamics of Water and Liquid Nitrogen in a Spherical Tank

    Science.gov (United States)

    Storey, Jedediah Morse

    2016-01-01

    Understanding, predicting, and controlling fluid slosh dynamics is critical to safety and improving performance of space missions when a significant percentage of the spacecraft's mass is a liquid. Computational fluid dynamics simulations can be used to predict the dynamics of slosh, but these programs require extensive validation. Many experimental and numerical studies of water slosh have been conducted. However, slosh data for cryogenic liquids is lacking. Water and cryogenic liquid nitrogen are used in various ground-based tests with a spherical tank to characterize damping, slosh mode frequencies, and slosh forces. A single ring baffle is installed in the tank for some of the tests. Analytical models for slosh modes, slosh forces, and baffle damping are constructed based on prior work. Select experiments are simulated using a commercial CFD software, and the numerical results are compared to the analytical and experimental results for the purposes of validation and methodology-improvement.

  3. Analytical solution and numerical simulation of the liquid nitrogen freezing-temperature field of a single pipe

    Science.gov (United States)

    Cai, Haibing; Xu, Liuxun; Yang, Yugui; Li, Longqi

    2018-05-01

    Artificial liquid nitrogen freezing technology is widely used in urban underground engineering due to its technical advantages, such as simple freezing system, high freezing speed, low freezing temperature, high strength of frozen soil, and absence of pollution. However, technical difficulties such as undefined range of liquid nitrogen freezing and thickness of frozen wall gradually emerge during the application process. Thus, the analytical solution of the freezing-temperature field of a single pipe is established considering the freezing temperature of soil and the constant temperature of freezing pipe wall. This solution is then applied in a liquid nitrogen freezing project. Calculation results show that the radius of freezing front of liquid nitrogen is proportional to the square root of freezing time. The radius of the freezing front also decreases with decreased the freezing temperature, and the temperature gradient of soil decreases with increased distance from the freezing pipe. The radius of cooling zone in the unfrozen area is approximately four times the radius of the freezing front. Meanwhile, the numerical simulation of the liquid nitrogen freezing-temperature field of a single pipe is conducted using the Abaqus finite-element program. Results show that the numerical simulation of soil temperature distribution law well agrees with the analytical solution, further verifies the reliability of the established analytical solution of the liquid nitrogen freezing-temperature field of a single pipe.

  4. Nitrogen

    Science.gov (United States)

    Apodaca, Lori E.

    2013-01-01

    The article presents an overview of the nitrogen chemical market as of July 2013, including the production of ammonia compounds. Industrial uses for ammonia include fertilizers, explosives, and plastics. Other topics include industrial capacity of U.S. ammonia producers CF Industries Holdings Inc., Koch Nitrogen Co., PCS Nitrogen, Inc., and Agrium Inc., the impact of natural gas prices on the nitrogen industry, and demand for corn crops for ethanol production.

  5. Liquid-liquid extraction from molten alkaline nitrates by using nitrogenous and organophosphorus derivatives

    International Nuclear Information System (INIS)

    Vittori, Olivier

    1971-01-01

    This research thesis reports the use of a system made of the LiNO 3 -KNO 3 eutectic at 160 deg. C and poly-phenyls in order to study the behaviour of phosphine and arsine oxides as extracting agents in a liquid-liquid process. In a first part, the author presents the studied system, its physical characteristics and its preparation, and the various analytical methods which have used. He discusses existing computation methods adapted to the separation of molten salts and organic phase, and proposes a specific method. Then, he reports the study of the behaviour of a phosphine oxide with Cobalt II and Nickel II, and discusses its application to the separation of this pair, Co II and Ni II. He highlights the different possibilities of three agents which are derivatives of phosphine and arsine in their ability to extract rare earths. A study of separation of rare earths is then addressed. The author reports the application of extraction equilibriums to the study of equilibriums in environments of molten salts with the Co II - chloride ions system. The author finally addresses the synergic phenomenon that pairs of neutral complexing agents of neighbouring structure or different donor central atom may display in liquid-liquid extraction

  6. A reliable procedure for decontamination before thawing of human specimens cryostored in liquid nitrogen: three washes with sterile liquid nitrogen (SLN2).

    Science.gov (United States)

    Parmegiani, Lodovico; Accorsi, Antonio; Bernardi, Silvia; Arnone, Alessandra; Cognigni, Graciela Estela; Filicori, Marco

    2012-10-01

    To report a washing procedure, to be performed as frozen specimens are taken out of cryobanks, to minimize the risk of hypothetical culture contamination during thawing. Basic research. Private assisted reproduction center. Two batches of liquid nitrogen (LN(2)) were experimentally contaminated, one with bacteria (Pseudomonas aeruginosa, Escherichia coli, Stenotrophomonas maltophilia) and the other with fungi (Aspergillus niger). Two hundred thirty-two of the most common human gamete/embryo vitrification carriers (Cryotop, Cryoleaf, Cryopette) were immersed in the contaminated LN(2) (117 in the bacteria and 25 in the fungi-contaminated LN(2)). The carriers were tested microbiologically, one group without washing (control) and the other after three subsequent washings in certified ultraviolet sterile liquid nitrogen (SLN(2)). The carriers were randomly allocated to the "three-wash procedure" (three-wash group, 142 carriers) or "no-wash" (control group, 90 carriers) using a specific software tool. Assessment of microorganism growth. In the no-wash control group, 78.6% of the carriers were contaminated by the bacteria and 100% by the fungi. No carriers were found to be contaminated, either by bacteria or fungi, after the three-wash procedure. The three-wash procedure with SLN(2) produced an efficient decontamination of carriers in extreme experimental conditions. For this reason, this procedure could be routinely performed in IVF laboratories for safe thawing of human specimens that are cryostored in nonhermetical cryocontainers, particularly in the case of open or single-straw closed vitrification systems. Copyright © 2012 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

  7. An investigation of an uninterruptible power supply (UPS) based on supercapacitor and liquid nitrogen hybridization system

    International Nuclear Information System (INIS)

    Zhang, Xinjing; Xue, Haobai; Xu, Yujie; Chen, Haisheng; Tan, Chunqing

    2014-01-01

    Highlights: • A hybrid UPS based on supercapacitor and liquid nitrogen engine is proposed. • The dynamic modelling of the hybrid UPS system is conducted. • The dynamic working performance is obtained and analysed based on the simulation. • The hybrid UPS enjoys environmental benignity, long life and easy maintenance. • It is a highly possible solution to replace conventional UPS systems. - Abstract: An uninterruptible power supply (UPS) system based on supercapacitor and liquid nitrogen (LN 2 ) hybridization is first introduced in this paper. Of the newly designed UPS, the supercapacitor reacts instantaneously once the main supply fails, and it also starts the LN 2 power system to produce continuing electricity for the customer. This hybrid UPS system is of environment cleanness, long life time, easy maintenaince, etc. A 10 kW model is analyzed in this study. A two-stage nitrogen expander is designed with the rated speed of 900 rpm as the long time power generation device of the LN 2 cycle. The UPS starting process calculation is carried out. The results reveal that commercial supercapacitors could fulfill this request. This UPS could be a competent choice for the UPS application. Further discussion indicates the LN 2 power system could be used widely from UPS to low carbon vehicles

  8. Conidiation of Penicillium camemberti in submerged liquid cultures is dependent on the nitrogen source.

    Science.gov (United States)

    Boualem, Khadidja; Labrie, Steve; Gervais, Patrick; Waché, Yves; Cavin, Jean-François

    2016-02-01

    To study the ability of a commercial Penicillium camemberti strain, used for Camembert type cheese ripening, to produce conidia during growth in liquid culture (LC), in media containing different sources of nitrogen as, industrially, conidia are produced by growth at the surface of a solid state culture because conidiation in stirred submerged aerobic LC is not known. In complex media containing peptic digest of meat, hyphae ends did not differentiate into phialides and conidia. Contrarily, in a synthetic media containing KNO3 as sole nitrogen source, hyphae ends differentiated into phialides producing 0.5 × 10(7) conidia/ml. Conidia produced in LC were 25 % less hydrophobic than conidia produced in solid culture, and this correlates with a seven-times-lower expression of the gene rodA encoding hydrophobin RodA in the mycelium grown in LC. Conidiation of P. camembertii is stimulated in iquid medium containing KNO3 as sole source of nitrogen and therefore opens up opportunities for using liquid medium in commercial productions.

  9. Real-Time, Non-Intrusive Detection of Liquid Nitrogen in Liquid Oxygen at High Pressure and High Flow

    Science.gov (United States)

    Singh, Jagdish P.; Yueh, Fang-Yu; Kalluru, Rajamohan R.; Harrison, Louie

    2012-01-01

    An integrated fiber-optic Raman sensor has been designed for real-time, nonintrusive detection of liquid nitrogen in liquid oxygen (LOX) at high pressures and high flow rates in order to monitor the quality of LOX used during rocket engine ground testing. The integrated sensor employs a high-power (3-W) Melles Griot diode-pumped, solid-state (DPSS), frequency-doubled Nd:YAG 532- nm laser; a modified Raman probe that has built-in Raman signal filter optics; two high-resolution spectrometers; and photomultiplier tubes (PMTs) with selected bandpass filters to collect both N2 and O2 Raman signals. The PMT detection units are interfaced with National Instruments Lab- VIEW for fast data acquisition. Studies of sensor performance with different detection systems (i.e., spectrometer and PMT) were carried out. The concentration ratio of N2 and O2 can be inferred by comparing the intensities of the N2 and O2 Raman signals. The final system was fabricated to measure N2 and O2 gas mixtures as well as mixtures of liquid N2 and LOX

  10. CooLN2Car: An Experimental Car Which Uses Liquid Nitrogen as Its Fuel

    Science.gov (United States)

    Parker, M. E.; Plummer, M. C.; Ordonez, C. A.

    1997-10-01

    A ``cryogenic" heat engine which operates using the atmosphere as a heat source and a cryogenic medium as a heat sink has been incorporated as the power system for an automobile. A 1973 Volkswagen Beetle has been converted and uses liquid nitrogen as its ``fuel." A Dewar was mounted in the car and provides nitrogen under pressure to two heat exchangers connected in parallel which use atmospheric heat to heat the nitrogen. The heat exchangers deliver compressed nitrogen gas to a vane-type pneumatic motor mounted in place of the original gasoline engine. Pressure in the tank is maintained internally at 1.2 MPa and is reduced to 0.7 MPa before the motor by a pressure regulator. A throttle, composed of a butterfly valve, is mounted between the regulator and the motor and is connected to the driver's accelerator peddle. The vehicle has good acceleration, a maximum range of 15 miles, and a maximum speed of 25 mph. A demonstration with the vehicle is planned.

  11. Steady-state subcooled nucleate boiling on a downward facing hemispherical surface

    International Nuclear Information System (INIS)

    Haddad, K.H.; Cheung, F.B.

    1996-01-01

    Steady-state nucleate boiling heat transfer experiments in saturated and subcooled water were conducted. The heating surface was a 0.305 m hemispherical aluminum vessel heated from the inside with water boiling on the outside. It was found that subcooling had very little effect on the nucleate boiling curve in the high heat flux regime where latent heat transport dominated. On the other hand, a relatively large effect of subcooling was observed in the low heat flux regime where sensible heat transport was important. Photographic records of the boiling phenomenon and the bubble dynamics indicated that in the high heat flux regime, boiling in the bottom center region of the vessel was cyclic in nature with a liquid heating phase, a bubble nucleation and growth phase, a bubble coalescence phase, and a large vapor mass ejection phase. At the same heat flux level, the size of the vapor masses was found to decrease from the bottom center toward the upper edge of the vessel, which was consistent with the observed increase in the critical heat flux in the flow direction along the curved heating surface

  12. Assessment of correlations and models for the prediction of CHF in water subcooled flow boiling

    Science.gov (United States)

    Celata, G. P.; Cumo, M.; Mariani, A.

    1994-01-01

    The present paper provides an analysis of available correlations and models for the prediction of Critical Heat Flux (CHF) in subcooled flow boiling in the range of interest of fusion reactors thermal-hydraulic conditions, i.e. high inlet liquid subcooling and velocity and small channel diameter and length. The aim of the study was to establish the limits of validity of present predictive tools (most of them were proposed with reference to light water reactors (LWR) thermal-hydraulic studies) in the above conditions. The reference dataset represents almost all available data (1865 data points) covering wide ranges of operating conditions in the frame of present interest (0.1 less than p less than 8.4 MPa; 0.3 less than D less than 25.4 mm; 0.1 less than L less than 0.61 m; 2 less than G less than 90.0 Mg/sq m/s; 90 less than delta T(sub sub,in) less than 230 K). Among the tens of predictive tools available in literature four correlations (Levy, Westinghouse, modified-Tong and Tong-75) and three models (Weisman and Ileslamlou, Lee and Mudawar and Katto) were selected. The modified-Tong correlation and the Katto model seem to be reliable predictive tools for the calculation of the CHF in subcooled flow boiling.

  13. Assessment of correlations and models for prediction of CHF in subcooled flow boiling

    International Nuclear Information System (INIS)

    Celata, G.P.; Mariani, A.; Cumo, M.

    1992-01-01

    This paper provides an analysis of available correlations and models for the prediction of Critical Heat Flux (CHF) in subcooled flow boiling in the ranges of interest of fusion reactor thermal-hydraulic conditions, i.e., high inlet liquid subcooling and velocity and small channel diameter and length. The aim of the study was to establish the limits of validity of present predictive tools (most of them were proposed with reference to LWR thermal-hydraulic studies) in the above conditions. The reference data-set represents most of available data covering wide ranges of operating conditions in the framework of present interest (0.1 s ub, in < 230 K). Among the tens of predictive tools available in literature, four correlations (Levy, Westinghouse, modified-Tong and Tong-75) and three models (Weisman and Ileslamlou Lee and Mudawar and Katto) were selected. The modified-Tong correlation and the Katto model seem to be reliable predictive tools for the calculation of the CHF in subcooled flow boiling

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

    International Nuclear Information System (INIS)

    Selbas, Resat; Kizilkan, Onder; Sencan, Arzu

    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 and superheating temperatures. A cost function is specified for the optimum conditions. All calculations are made for three refrigerants: R22, R134a, and R407c. Thermodynamic properties of refrigerants are formulated using the Artificial Neural Network methodology

  15. Prediction of void fraction in subcooled flow boiling

    International Nuclear Information System (INIS)

    Petelin, S.; Koncar, B.

    1998-01-01

    The information on heat transfer and especially on the void fraction in the reactor core under subcooled conditions is very important for the water-cooled nuclear reactors, because of its influence upon the reactivity of the systems. This paper gives a short overview of subcooled boiling phenomenon and indicates the simplifications made by the RELAP5 model of subcooled boiling. RELAP5/MOD3.2 calculations were compared with simple one-dimensional models and with high-pressure Bartolomey experiments.(author)

  16. Application of the Open Cycle Stirling Engine Driven with Liquid Nitrogen for the Non-Polluting Automobiles

    Directory of Open Access Journals (Sweden)

    M.B. Kravchenko

    2017-10-01

    Full Text Available Progress on advancing technology of using liquid nitrogen for the non-polluting automobiles is reported. It is shown that the low exergy efficiency of the known engines fueled with liquid nitrogen has discredited the very idea of a cryomobile. The design of the open-cycle cryogenic Stirling engine is proposed. This engine allows extracting up to 57% of the exergy accumulated in liquid nitrogen. The method used to calculate of such open-cycle Stirling engine is described and the calculation results and discussion are presented. It is shown that 200 liters of liquid nitrogen is sufficient for 180 km range of cryomobile at speed of 55 km/h, while a full charge of the 300-kilogram battery of Nissan LEAF electric vehicle is sufficient for a range of 160 km. Use of liquid nitrogen or liquid air as an energy vector in a transport will not require scarce materials, and, in comparison with using of lithium-ion batteries or hydrogen, this will require less capital investment.

  17. On the influence of water subcooling and melt jet parameters on debris formation

    Energy Technology Data Exchange (ETDEWEB)

    Manickam, Louis, E-mail: louis@safety.sci.kth.se; Kudinov, Pavel; Ma, Weimin; Bechta, Sevostian; Grishchenko, Dmitry

    2016-12-01

    Highlights: • Melt and water configuration effects on debris formation is studied experimentally. • Melt superheat and water subcooling are most influential compared to jet size. • Melt-water configuration and material properties influence particle fracture rate. • Results are compared with large scale experiments to study effect of spatial scales. - Abstract: Breakup of melt jet and formation of a porous debris bed at the base-mat of a flooded reactor cavity is expected during the late stages of a severe accident in light water reactors. Debris bed coolability is determined by the bed properties including particle size, morphology, bed height and shape as well as decay heat. Therefore understanding of the debris formation phenomena is important for assessment of debris bed coolability. A series of experiments was conducted in MISTEE-Jet facility by discharging binary-oxide mixtures of WO{sub 3}–Bi{sub 2}O{sub 3} and WO{sub 3}–ZrO{sub 2} into water in order to investigate properties of resulting debris. The effect of water subcooling, nozzle diameter and melt superheat was addressed in the tests. Experimental results reveal significant influence of water subcooling and melt superheat on debris size and morphology. Significant differences in size and morphology of the debris at different melt release conditions is attributed to the competition between hydrodynamic fragmentation of liquid melt and thermal fracture of the solidifying melt droplets. The particle fracture rate increases with increased subcooling. Further the results are compared with the data from larger scale experiments to discern the effects of spatial scales. The present work provides data that can be useful for validation of the codes used for the prediction of debris formation phenomena.

  18. Thermodynamic performance evaluation of transcritical carbon dioxide refrigeration cycle integrated with thermoelectric subcooler and expander

    International Nuclear Information System (INIS)

    Dai, Baomin; Liu, Shengchun; Zhu, Kai; Sun, Zhili; Ma, Yitai

    2017-01-01

    New configurations of transcritical CO_2 refrigeration cycle combined with a thermoelectric (TE) subcooler and an expander (TES+EXP_H_M and TES+EXP_M_L) are proposed. The expander can operate between the high-pressure to the vessel pressure, or from vessel pressure to evaporation pressure. A power system is utilized to balance and supply power to thermoelectric subcooler and compressor. Thermodynamic performance optimizations and analyses are presented. Comparisons are carried out with the BASE, EXP_H_M, EXP_M_L, and TES cycles. The results show that the coefficient of performance (COP) improvement is more notable when the expander is installed between the liquid receiver and the evaporator. Maximum COP is obtained for the new cycles with a simultaneous optimization of discharge pressure and subcooling temperature. The new proposed TES+EXP_M_L cycle shows an excellent and steady performance than other cycles. It operates not only with the highest COP, but also the lowest discharge pressure. Under the working conditions of high gas cooler outlet temperature or low evaporation temperature, the merits of COP improvement and discharge pressure reduction are more prominent. The new cycle is more suitable for the hot regions where the CO_2 can not be sufficiently subcooled or the refrigerated space operates at low evaporation temperature. - Highlights: • New configurations of transcritical CO_2 refrigeration cycle are proposed. • New cycles are optimized and compared with other cycles. • The position of expander has an evident influence on the performance of CO_2 cycle. • TES+EXP_M_L cycle shows the highest COP and lowest discharge pressure. • The range of application for the TES+EXP_M_L cycle is recommended.

  19. Liquid nitrogen spray cryotherapy in Barrett's esophagus with high-grade dysplasia: long-term results.

    Science.gov (United States)

    Gosain, Sonia; Mercer, Kim; Twaddell, William S; Uradomo, Lance; Greenwald, Bruce D

    2013-08-01

    Liquid nitrogen endoscopic spray cryotherapy can safely and effectively eradicate high-grade dysplasia in Barrett's esophagus (BE-HGD). Long-term data on treatment success and safety are lacking. To assess the long-term safety and efficacy of spray cryotherapy in patients with BE-HGD. Single-center, retrospective study. Tertiary-care referral center. A total of 32 patients with BE-HGD of any length. Patients were treated with liquid nitrogen spray cryotherapy every 8 weeks until complete eradication of HGD (CE-HGD) and intestinal metaplasia (CE-IM) was found by endoscopic biopsy. Surveillance endoscopy with biopsies was performed for at least 2 years. CE-HGD, CE-IM, durability of response, disease progression, and adverse events. CE-HGD was 100% (32/32), and CE-IM was 84% (27/32) at 2-year follow-up. At last follow-up (range 24-57 months), CE-HGD was 31/32 (97%), and CE-IM was 26/32 (81%). Recurrent HGD was found in 6 (18%), with CE-HGD in 5 after repeat treatment. One patient progressed to adenocarcinoma, downgraded to HGD after repeat cryotherapy. BE segment length ≥3 cm was associated with a higher recurrence of IM (P = .004; odds ratio 22.6) but not HGD. No serious adverse events occurred. Stricture was seen in 3 patients (9%), all successfully dilated. Retrospective study design, small sample size. In patients with BE-HGD, liquid nitrogen spray cryotherapy has an acceptable safety profile and success rate for eliminating HGD and IM and is associated with a low rate of recurrence or progression to cancer with long-term follow-up. Copyright © 2013 American Society for Gastrointestinal Endoscopy. Published by Mosby, Inc. All rights reserved.

  20. Feasibility of refreezing human spermatozoa through the technique of liquid nitrogen vapor

    Directory of Open Access Journals (Sweden)

    Sidney Verza Jr

    2004-12-01

    Full Text Available OBJECTIVE: To assess the feasibility of refreezing human semen using the technique of liquid nitrogen vapor with static phases. MATERIALS AND METHODS: Twenty samples from 16 subjects who required disposal of their cryopreserved semen were thawed, corresponding to 6 cancer patients and 10 participants in the assisted reproduction (AR program. Samples were refrozen using the technique of liquid nitrogen vapor with static phases, identical to the one used for the initial freezing, and thawed again after 72 hours. We assessed the concentration of motile spermatozoa, total and progressive percent motility and spermatic vitality, according to criteria of the World Health Organization (WHO, as well as spermatic morphology according to the strict Kruger criterion, after the first and after the second thawing. RESULTS: We observed a significant decrease in all the parameters evaluated between the first and the second thawing. Median values for the concentration of motile spermatozoa decreased from 2.0x10(6/mL to 0.1x10(6/mL (p < 0.01; total percent motility from 42% to 22.5% (p < 0.01; progressive percent motility from 34% to 9.5% (p < 0.01; vitality from 45% to 20% (p < 0.01; and morphology from 5% to 5% (p = 0.03. There was no significant difference in the spermatic parameters between the cancer and assisted reproduction groups, both after the first and after the second thawing. We observed that in 100% of cases there was retrieval of motile spermatozoa after the second thawing. CONCLUSIONS: Refreezing of human semen by the technique of liquid nitrogen vapor allows the retrieval of viable spermatozoa after thawing.

  1. Experimental measurement of the interfacial heat transfer coefficients of subcooled flow boiling using micro-thermocouple and double directional images

    International Nuclear Information System (INIS)

    Seong-Jin Kim; Goon-Cherl Park

    2005-01-01

    Full text of publication follows: Models or correlations for phase interface are needed to analyze the multi-phase flow. Interfacial heat transfer coefficients are important to constitute energy equation of multi-phase flow, specially. In subcooled boiling flow, bubble condensation at the bubble-liquid interface is a major mechanism of heat transfer within bulk subcooled liquid. Bubble collapse rates and temperatures of each phase are needed to determine the interfacial heat transfer coefficient for bubble condensation. Bubble collapse rates were calculated through image processing in single direction, generally. And in case of liquid bulk temperature, which has been obtained by general temperature sensor such as thermocouple, was used. However, multi-directional images are needed to analyze images due to limitations of single directional image processing. Also, temperature sensor, which has a fast response time, must be used to obtain more accurate interfacial heat transfer coefficient. Low pressure subcooled water flow experiments using micro-thermocouple and double directional image processing with mirrors were conducted to investigate bubble condensation phenomena and to modify interfacial heat transfer correlation. Experiments were performed in a vertical subcooled boiling flow of a rectangular channel. Bubble condensing traces with respect to time were recorded by high speed camera in double direction and bubble collapse rates were calculated by processing recorded digital images. Temperatures were measured by micro-thermocouple, which is a K-type with a 12.7 μm diameter. The liquid temperature was estimated by the developed algorithm to discriminate phases and find each phase temperature in the measured temperature including both liquid and bubble temperature. The interfacial heat transfer coefficient for bubble condensation was calculated from the bubble collapse rates and the estimated liquid temperature, and its correlation was modified. The modified

  2. Experimentation of netlike hydro gel nitrogen containing polymer sorbents for biological liquids purification

    International Nuclear Information System (INIS)

    Karieva, Z.M.; Karimova, N. Kh.

    2003-01-01

    The high efficiency of hydrogels synthesized earlier in comparison with Pharmacopoeia sorbents are interesting to study comprehensively for the number of the toxins of biological liquids. Taking into considerations the high electoral sorption ability of ethynilpiperidol polymers to the hydro phobic interaction it may be suggested that they have a high detoxication ability. The detoxication characteristics of studied polymers have advantages over the known sorbents. Experiences with animals showed that in identical conditions of experiment in application of netlike polymers the survival grew 90%. Synthesis and investigations of netlike hydrogels polymer materials on nitrogen containing monomers of ethynil piperidol were given in the work. (author)

  3. Radiolysis effects in sub-cooled nucleate boiling

    International Nuclear Information System (INIS)

    Dickinson, S.; Henshaw, J.; Tuson, A.; Sims, H.E.

    2002-01-01

    A hydrogen depleted region may form in the water during bubble formation when boiling occurs in a PWR. This would arise from stripping of gases into the steam phase. The depleted water may then become oxidising due to radiolysis forming H 2 O 2 . The presence of radiolytic oxidising conditions is one of the mechanisms proposed to explain deposits formed in Axial Offset Anomalies. This work describes a model that has been developed to examine this behaviour. The model deals with bubble growth and material transport as well as the radiolysis chemistry. The model simulates diffusion of species through the gas/liquid boundary layer. The appropriate mass conservation equations for this problem are described and the results of their numerical solution discussed. This model indicates the importance of the assumed boundary conditions on the results of the calculations. These boundary conditions are discussed in detail and the most appropriate ones for the actual reactor situation are outlined. The conclusion of this modelling study is that at normal PWR operating conditions of 40 cc H 2 (STP) kg -1 it is unlikely that radiolysis in a subcooled boiling region would be important. The situation is more ambiguous at the 1 to 5 cc H 2 (STP) kg -1 range. (author)

  4. Radiolysis effects in sub-cooled nucleate boiling

    Energy Technology Data Exchange (ETDEWEB)

    Dickinson, S.; Henshaw, J.; Tuson, A.; Sims, H.E. [AEA Technology (United Kingdom)

    2002-07-01

    A hydrogen depleted region may form in the water during bubble formation when boiling occurs in a PWR. This would arise from stripping of gases into the steam phase. The depleted water may then become oxidising due to radiolysis forming H{sub 2}O{sub 2}. The presence of radiolytic oxidising conditions is one of the mechanisms proposed to explain deposits formed in Axial Offset Anomalies. This work describes a model that has been developed to examine this behaviour. The model deals with bubble growth and material transport as well as the radiolysis chemistry. The model simulates diffusion of species through the gas/liquid boundary layer. The appropriate mass conservation equations for this problem are described and the results of their numerical solution discussed. This model indicates the importance of the assumed boundary conditions on the results of the calculations. These boundary conditions are discussed in detail and the most appropriate ones for the actual reactor situation are outlined. The conclusion of this modelling study is that at normal PWR operating conditions of 40 cc H{sub 2} (STP) kg{sup -1} it is unlikely that radiolysis in a subcooled boiling region would be important. The situation is more ambiguous at the 1 to 5 cc H{sub 2} (STP) kg{sup -1} range. (author)

  5. Determination of heat transfer coefficients in plastic French straws plunged in liquid nitrogen.

    Science.gov (United States)

    Santos, M Victoria; Sansinena, M; Chirife, J; Zaritzky, N

    2014-12-01

    The knowledge of the thermodynamic process during the cooling of reproductive biological systems is important to assess and optimize the cryopreservation procedures. The time-temperature curve of a sample immersed in liquid nitrogen enables the calculation of cooling rates and helps to determine whether it is vitrified or undergoes phase change transition. When dealing with cryogenic liquids, the temperature difference between the solid and the sample is high enough to cause boiling of the liquid, and the sample can undergo different regimes such as film and/or nucleate pool boiling. In the present work, the surface heat transfer coefficients (h) for plastic French straws plunged in liquid nitrogen were determined using the measurement of time-temperature curves. When straws filled with ice were used the cooling curve showed an abrupt slope change which was attributed to the transition of film into nucleate pool boiling regime. The h value that fitted each stage of the cooling process was calculated using a numerical finite element program that solves the heat transfer partial differential equation under transient conditions. In the cooling process corresponding to film boiling regime, the h that best fitted experimental results was h=148.12±5.4 W/m(2) K and for nucleate-boiling h=1355±51 W/m(2) K. These values were further validated by predicting the time-temperature curve for French straws filled with a biological fluid system (bovine semen-extender) which undergoes freezing. Good agreement was obtained between the experimental and predicted temperature profiles, further confirming the accuracy of the h values previously determined for the ice-filled straw. These coefficients were corroborated using literature correlations. The determination of the boiling regimes that govern the cooling process when plunging straws in liquid nitrogen constitutes an important issue when trying to optimize cryopreservation procedures. Furthermore, this information can lead to

  6. Experimental investigation of passive thermodynamic vent system (TVS) with liquid nitrogen

    Science.gov (United States)

    Bae, Junhyuk; Yoo, Junghyun; Jin, Lingxue; Jeong, Sangkwon

    2018-01-01

    Thermodynamic vent system (TVS) is an attractive technology to maintain an allowable pressure level of a cryogenic propellant storage in a spacecraft under micro-gravity condition. There are two types of TVS; active or passive. In this paper, the passive TVS which does not utilize a cryogenic liquid circulation pump is experimentally investigated with liquid nitrogen and numerically analyzed by thermodynamic and heat transfer model. A cylindrical copper tank, which is 198 mm in inner diameter and 216 mm in height, is utilized to suppress a thermal-stratification effect of inside cryogenic fluid. A coil heat exchanger, which is 3 m in length and 6.35 mm in outer diameter, and a fixed size orifice of which diameter is 0.4 mm are fabricated to remove heat from the stored fluid to the vented flow. Each vent process is initiated at 140 kPa and ended at 120 kPa with liquid nitrogen fill levels which are 30%, 50% and 70%, respectively. In the numerical model, the fluid in the tank is assumed to be homogeneous saturated liquid-vapor. Mass and energy balance equations with heat transfer conditions suggested in this research are considered to calculate the transient pressure variation in the tank and the amount of heat transfer across the heat exchanger. We achieve the average heat rejection rate of more than 9 W by TVS and conclude that the passive TVS operates satisfactorily. In addition, the prediction model is verified by experimental results. Although the model has limitation in providing accurate results, it can surely predict the tendency of pressure and temperature changes in the tank. Furthermore, the model can suggest how we can improve the heat exchanger design to enhance an overall efficiency of passive TVS. Moreover, the performance of passive TVS is compared with other cryogenic vent systems (direct vent system and active TVS) by suggested performance indicator.

  7. Subcooler assembly for SSC single magnet test program

    International Nuclear Information System (INIS)

    Wu, K.C.; Brown, D.P.; Sondericker, J.H.; Farah, Y.; Zantopp, D.; Nicoletti, A.

    1991-01-01

    A subcooler assembly has been designed, constructed and installed in the MAGCOOL magnet test area at Brookhaven National Laboratory. Since July 1989, it has been used for testing SSC magnets. This subcooler assembly and cryogenic system are the first of its kind ever built. Today, with more than 5000 hours of operating time, the subcooler has proved to be a reliable unit with individual components meeting design expectations. The lowest temperatures achieved with one SSC dipole are 3.0 K at the suction of the cold vacuum pump and 3.2 K at the return of the magnet. The system performs well in both steady state operation and during magnet quench, subcooling, cooldown and warmup. 4 refs., 7 figs

  8. A measurement of the absorption of liquid argon scintillation light by dissolved nitrogen at the part-per-million level

    International Nuclear Information System (INIS)

    Jones, B J P; Chiu, C S; Conrad, J M; Ignarra, C M; Katori, T; Toups, M

    2013-01-01

    We report on a measurement of the absorption length of scintillation light in liquid argon due to dissolved nitrogen at the part-per-million (ppm) level. We inject controlled quantities of nitrogen into a high purity volume of liquid argon and monitor the light yield from an alpha source. The source is placed at different distances from a cryogenic photomultiplier tube assembly. By comparing the light yield from each position we extract the absorption cross section of nitrogen. We find that nitrogen absorbs argon scintillation light with strength of (1.51±0.15) × 10 −4 cm −1 ppm −1 , corresponding to an absorption cross section of (4.99±0.51) × 10 −21 cm 2 molecule −1 . We obtain the relationship between absorption length and nitrogen concentration over the 0 to 50 ppm range and discuss the implications for the design and data analysis of future large liquid argon time projection chamber (LArTPC) detectors. Our results indicate that for a current-generation LArTPC, where a concentration of 2 parts per million of nitrogen is expected, the attenuation length due to nitrogen will be 30±3 meters

  9. Results of a photographic study of subcooled forced-convection boiling of high-pressure water and Freon-12

    International Nuclear Information System (INIS)

    Macbeth, R.V.; Wood, R.W.

    1980-06-01

    The use of a 'Freon' to model high-pressure boiling water has been employed successfully in a number of applications. A prerequisite in modelling is that a well tried and proven basis for the modelling exists. This is not entirely the situation with subcooled boiling however, since past work had tended to concentrate on bulk boiling conditions. Since many of the questions that arise in the design of subcooled boiling systems are concerned with two-phase flow structure, it was decided to place emphasis on attempting to match photographs of subcooled two-phase conditions in high-pressure water (at 55.2 and 82.7 bar) with those of Freon-12 at the corresponding pressures (8.13 and 12.75 bar). A special test-section was constructed giving visual access to a vapour forming region and to an unheated region into which vapour bubbles were drawn by the flow of subcooled liquid. The photographs obtained show that close similarity of two-phase flow structure exists in water and in Freon at corresponding conditions as determined by a previously established modelling procedure. (U.K.)

  10. The Linear Thermal Expansion of Bulk Nanocrystalline Ingot Iron from Liquid Nitrogen to 300 K.

    Science.gov (United States)

    Wang, S G; Mei, Y; Long, K; Zhang, Z D

    2009-09-17

    The linear thermal expansions (LTE) of bulk nanocrystalline ingot iron (BNII) at six directions on rolling plane and conventional polycrystalline ingot iron (CPII) at one direction were measured from liquid nitrogen temperature to 300 K. Although the volume fraction of grain boundary and residual strain of BNII are larger than those of CPII, LTE of BNII at the six measurement directions were less than those of CPII. This phenomenon could be explained with Morse potential function and the crystalline structure of metals. Our LTE results ruled out that the grain boundary and residual strain of BNII did much contribution to its thermal expansion. The higher interaction potential energy of atoms, the less partial derivative of interaction potential energy with respect to temperature T and the porosity free at the grain boundary of BNII resulted in less LTE in comparison with CPII from liquid nitrogen temperature to 300 K. The higher LTE of many bulk nanocrystalline materials resulted from the porosity at their grain boundaries. However, many authors attributed the higher LTE of many nanocrystalline metal materials to their higher volume fraction of grain boundaries.

  11. The Linear Thermal Expansion of Bulk Nanocrystalline Ingot Iron from Liquid Nitrogen to 300 K

    Directory of Open Access Journals (Sweden)

    Mei Y

    2009-01-01

    Full Text Available Abstract The linear thermal expansions (LTE of bulk nanocrystalline ingot iron (BNII at six directions on rolling plane and conventional polycrystalline ingot iron (CPII at one direction were measured from liquid nitrogen temperature to 300 K. Although the volume fraction of grain boundary and residual strain of BNII are larger than those of CPII, LTE of BNII at the six measurement directions were less than those of CPII. This phenomenon could be explained with Morse potential function and the crystalline structure of metals. Our LTE results ruled out that the grain boundary and residual strain of BNII did much contribution to its thermal expansion. The higher interaction potential energy of atoms, the less partial derivative of interaction potential energy with respect to temperature T and the porosity free at the grain boundary of BNII resulted in less LTE in comparison with CPII from liquid nitrogen temperature to 300 K. The higher LTE of many bulk nanocrystalline materials resulted from the porosity at their grain boundaries. However, many authors attributed the higher LTE of many nanocrystalline metal materials to their higher volume fraction of grain boundaries.

  12. Development of liquid-nitrogen-cooling friction stir spot welding for AZ31 magnesium alloy joints

    Science.gov (United States)

    Wu, Dong; Shen, Jun; Zhou, Meng-bing; Cheng, Liang; Sang, Jia-xing

    2017-10-01

    A liquid-nitrogen-cooling friction stir spot welding (C-FSSW) technology was developed for welding AZ31 magnesium alloy sheets. The liquid-nitrogen cooling degraded the deformability of the welded materials such that the width of interfacial cracks increased with increasing cooling time. The grain size of the stirred zone (SZ) and the heat-affected zone (HAZ) of the C-FSSW-welded joints decreased, whereas that of the thermomechanically affected zone (TMAZ) increased with increasing cooling time. The maximum tensile shear load of the C-FSSW-welded joints welded with a cooling time of 5 or 7 s was larger than that of the friction stir spot welding (FSSW)-welded joint, and the tensile shear load decreased with increasing cooling time. The microhardness of the C-FSSW-welded joints was greater than that of the FSSW-welded joint. Moreover, the microhardness of the SZ and the HAZ of the C-FSSW-welded joints increased, whereas that of the TMAZ decreased, with increasing cooling time.

  13. Changes in morphology of long bone marrow tissue of rats submitted to cryotherapy with liquid nitrogen.

    Science.gov (United States)

    Costa, Fábio Wildson Gurgel; Pessoa, Rosana Maria Andrade; Nogueira, Carlos Bruno Pinheiro; Pereira, Karuza Maria Alves; Brito, Gerly Anne de Castro; Soares, Eduardo Costa Studart

    2012-02-01

    To study the main effects of local use of liquid nitrogen on bone marrow tissue in rats. The femoral diaphyses of 42 Wistar rats were exposed to three local and sequential applications of liquid nitrogen for one or two minutes, intercalated with periods of five minutes of passive thawing. The animals were sacrificed after one, two, four and 12 weeks and the specimens obtained were analyzed histomorphologically. In the second experimental week of one-minute protocol, histological degree of inflammation obtained a mean score of one (mild), ranging from 0 (absent or scarce) and two (moderate) (Kruskal-Wallis test p=0.01). In the second experimental week of two-minute protocol, degree of inflammation to the medullar tissue obtained an average score of two (Kruskal-Wallis test p=0.01). The degree of inflammation of the bone marrow tissue was higher in protocol of three applications of two minutes compared to protocol of three applications of one minute.

  14. Soft X-ray and cathodoluminescence measurement, optimisation and analysis at liquid nitrogen temperatures

    Science.gov (United States)

    MacRae, C. M.; Wilson, N. C.; Torpy, A.; Delle Piane, C.

    2018-01-01

    Advances in field emission gun electron microprobes have led to significant gains in the beam power density and when analysis at high resolution is required then low voltages are often selected. The resulting beam power can lead to damage and this can be minimised by cooling the sample down to cryogenic temperatures allowing sub-micrometre imaging using a variety of spectrometers. Recent advances in soft X-ray emission spectrometers (SXES) offer a spectral tool to measure both chemistry and bonding and when combined with spectral cathodoluminescence the complementary techniques enable new knowledge to be gained from both mineral and materials. Magnesium and aluminium metals have been examined at both room and liquid nitrogen temperatures by SXES and the L-emission Fermi-edge has been observed to sharpen at the lower temperatures directly confirming thermal broadening of the X-ray spectra. Gains in emission intensity and resolution have been observed in cathodoluminescence for liquid nitrogen cooled quartz grains compared to ambient temperature quartz. This has enabled subtle growth features at quartz to quartz-cement boundaries to be imaged for the first time.

  15. Progressive Tool Wear in Cryogenic Machining: The Effect of Liquid Nitrogen and Carbon Dioxide

    Directory of Open Access Journals (Sweden)

    Yusuf Kaynak

    2018-05-01

    Full Text Available This experimental study focuses on various cooling strategies and lubrication-assisted cooling strategies to improve machining performance in the turning process of AISI 4140 steel. Liquid nitrogen (LN2 and carbon dioxide (CO2 were used as cryogenic coolants, and their performances were compared with respect to progression of tool wear. Minimum quantity lubrication (MQL was also used with carbon dioxide. Progression of wear, including flank and nose, are the main outputs examined during experimental study. This study illustrates that carbon dioxide-assisted cryogenic machining alone and with minimum quantity lubrication does not contribute to decreasing the progression of wear within selected cutting conditions. This study also showed that carbon dioxide-assisted cryogenic machining helps to increase chip breakability. Liquid nitrogen-assisted cryogenic machining results in a reduction of tool wear, including flank and nose wear, in the machining process of AISI 4140 steel material. It was also observed that in the machining process of this material at a cutting speed of 80 m/min, built-up edges occurred in both cryogenic cooling conditions. Additionally, chip flow damage occurs in particularly dry machining.

  16. Operational experience with double acting piston pumps for cryogenic helium and nitrogen

    International Nuclear Information System (INIS)

    Vosswinkel, F.

    1978-01-01

    The design of a high efficiency double acting piston pump suitable for pumping liquefied gases at cryogenic temperatures for cable cooling, is reported. The pump has proved flexible, reliable and efficient in operation. The plunger-type pumps can be used for filling cryostats or dewars with liquid helium or nitrogen from a pressure free or pressurized storage vessel, or as circulators for subcooled, saturated and/or supercritical helium in large scale cooling experiments. Flow rates of up to 17 g/s, maximum operating pressure of 600 kPa absolute and maximum differential pressure of approximately 100 kPa are obtained. (UK)

  17. Liquid nitrogen vapor is comparable to liquid nitrogen for storage of cryopreserved human sperm: evidence from the characteristics of post-thaw human sperm.

    Science.gov (United States)

    Hu, Jingmei; Zhao, Shidou; Xu, Chengyan; Zhang, Lin; Lu, Shaoming; Cui, Linlin; Ma, Jinlong; Chen, Zi-Jiang

    2015-11-01

    To compare the differences in the characteristics of post-thaw human sperm after storage in either liquid nitrogen (LN2; -196 °C) or LN2 vapor (-167 °C). Experimental study. University hospital. Thirty healthy volunteers who agreed to donate their normal semen samples for infertility or research were included in the study. Semen samples (n = 30) were divided into eight aliquots and frozen. Four aliquots of each human semen sample were stored in LN2 (-196 °C), and the other four aliquots were stored in LN2 vapor (-167 °C). After 1, 3, 6, or 12 months, samples were thawed and analyzed. The motility was evaluated by the manual counting method. The viability was estimated by eosin staining. The morphology was analyzed by Diff-Quik staining. The sperm DNA integrity was determined with acridine orange fluorescent staining, and acrosin activity was assayed by the modified Kennedy method. The characteristics of post-thaw human sperm, including motility, viability, morphology, DNA integrity, and acrosin activity, showed no significant difference between LN2 and LN2 vapor storage for the different time periods. LN2 vapor was comparable to LN2 in post-thaw sperm characteristics, suggesting that LN2 vapor may be substituted for LN2 for the long-term storage of human sperm. Copyright © 2015 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

  18. Critical heat flux with subcooled boiling of water at low pressure

    International Nuclear Information System (INIS)

    Chen Yuzhou; Zhou Runbin; Hao Laomi; Chen Haiyan

    1997-01-01

    The critical heat flux experiment has been performed in round tubes of 10 and 16 mm in diameter with different heating length, covering the range of pressure 1.5-16.7 bar, velocity 1.4-15.4 m/s and exit subcooling 30-136 K. The experimental data and empirical correlations are presented. Based on the results an evaluation of some correlations and 1995 CHF look-up table is made. For the conditions tested the effect of diameter on the critical heat flux is found to be related to the liquid velocity. (author)

  19. Tolerability and effectiveness of liquid nitrogen spray cryotherapy with very short freeze times in the treatment of xanthelasma palpebrarum.

    Science.gov (United States)

    Labandeira, Javier; Vázquez-Osorio, Igor; Figueroa-Silva, Olalla; Pereiro, Manuel; Toribio, Jaime

    2015-01-01

    Xanthelasma are cholesterol-filled, soft, yellow plaques that usually appear on the medial aspects of the eyelids bilaterally. They are always benign lesions so therapy is usually undertaken only for cosmetic reasons. Surgical excision, chemical peeling with tricholoroacetic acid, and laser ablation are commonly used treatments. Liquid nitrogen cryotherapy is a potentially effective but rarely used treatment due to the risk of intense eyelid swelling. We report on our experience with four of our patients, and propose an explanation for the effectiveness of gentle liquid nitrogen spray cryotherapy in xanthelasma. We consider that gentle liquid nitrogen cryotherapy should be used in the treatment of xanthelasma due to the ease of application and low risk of adverse effects. © 2015 Wiley Periodicals, Inc.

  20. Storage of Euschistus heros Eggs (Fabricius) (Hemiptera: Pentatomidae) in Liquid Nitrogen for Parasitization by Telenomus podisi Ashmead (Hymenoptera: Platygastridae).

    Science.gov (United States)

    Favetti, B M; Butnariu, A R; Doetzer, A K

    2014-06-01

    Records in the literature with regard to the influence of freezing of pentatomid eggs on parasitism by microhymenopterans are scarce. In this research, we compared the storage of Euschistus heros (Fabricius) (Hemiptera: Pentatomidae) eggs in liquid nitrogen for different periods with the objective of optimizing the multiplication of Telenomus podisi Ashmead (Hymenoptera: Platygastridae) in the laboratory. Fresh eggs of E. heros were exposed (S3, S6) or not (NS3, NS6) to UV light for 30 min and stored in 1.5-mL plastic vials in liquid nitrogen either for 3 (S3, NS3) or 6 months (S6, NS6), and egg suitability to parasitoid development was compared to control eggs exposed (SC) or not (NSC) to UV treatment. Global data analysis showed that E. heros eggs stored in liquid nitrogen with or without UV treatment, for 3 or 6 months, were suitable for T. podisi parasitization.

  1. Calculation of neutron and gamma-ray energy spectra in liquid air and liquid nitrogen due to 14-MeV neutron and californium-252 sources

    International Nuclear Information System (INIS)

    Straker, E.A.; Gritzner, M.L.; Harris, L. Jr.

    1978-01-01

    Calculations of neutron and gamma-ray fluences from 14-MeV neutron and 252 Cf sources in liquid air and liquid nitrogen have been performed. These calculations were made specifically for comparison with experimental data measured at Stohl, Federal Republic of Germany. The discrete-ordinates method was utilized with neutron and gamma-ray cross sections from ENDF/B-IV. One-dimensional calculational models were developed for the sources and tank. Limited comparisons are made with experimental data

  2. LOFT system structural response during subcooled blowdown

    International Nuclear Information System (INIS)

    Martinell, J.S.

    1978-01-01

    The Loss-of-Fluid Test (LOFT) facility is a highly instrumented, pressurized water reactor test system designed to be representative of large pressurized water reactors (LPWRs) for the simulation of loss-of-coolant accidents (LOCAs). Detailed structural analysis and appropriate instrumentation (accelerometers and strain gages) on the LOFT system provided information for evaluation of the structural response of the LOFT facility for loss-of-coolant experiment (LOCE) induced loads. In general, the response of the system during subcooled blowdown was small with typical structural accelerations below 2.0 G's and dynamic strains less than 150 x 10 - 6 m/m. The accelerations measured at the steam generator and simulated steam generator flange exceeded LOCE design values; however, integration of the accelerometer data at these locations yielded displacements which were less than one half of the design values associated with a safe shutdown earthquake (SSE), which assures structural integrity for LOCE loads. The existing measurement system was adequate for evaluation of the LOFT system response during the LOCEs. The conditions affecting blowdown loads during nuclear LOCEs will be nearly the same as those experienced during the nonnuclear LOCEs, and the characteristics of the structural response data in both types of experiments are expected to be the same. The LOFT system is concluded to be adequately designed and further analysis of the LOFT system with structural codes is not required for future LOCE experiments

  3. Thermodynamic analysis of chromium solubility data in liquid lithium containing nitrogen: Comparison between experimental data and computer simulation

    International Nuclear Information System (INIS)

    Krasin, Valery P.; Soyustova, Svetlana I.

    2015-01-01

    The mathematical formalism for description of solute interactions in dilute solution of chromium and nitrogen in liquid lithium have been applied for calculating of the temperature dependence of the solubility of chromium in liquid lithium with the various nitrogen contents. It is shown that the derived equations are useful to provide understanding of a relationship between thermodynamic properties and local ordering in the Li–Cr–N melt. Comparison between theory and data reported in the literature for solubility of chromium in nitrogen-contaminated liquid lithium, was allowed to explain the reasons of the deviation of the experimental semi-logarithmic plot of chromium content in liquid lithium as a function of the reciprocal temperature from a straight line. - Highlights: • The activity coefficient of chromium in ternary melt can be obtained by means of integrating the Gibbs–Duhem equation. • In lithium with the high nitrogen content, the dependence of a logarithm of chromium solubility as a function of the reciprocal temperature has essentially nonlinear character. • At temperatures below a certain threshold, the process of dissolution of chromium in lithium will be controlled by the equilibrium concentration of nitrogen required for the formation of ternary nitride Li_9CrN_5at a given temperature.

  4. Gamma irradiation of hydrocarbon-liquid nitrogen systems and the synthesis of ammonia

    International Nuclear Information System (INIS)

    Fleming, H.L.

    1982-01-01

    The 60 Co-gamma radiolysis of hydrocarbons (HC)-liquid N 2 mixtures at 77 0 K and 1.8 atm of pressure was investigated. Batch irradiation studies of methane, ethane, and ethylene and semibatch studies of methane were made in the presence and absence of transition metal oxide catalysts. In noncatalyzed systems, the effects of varying the radiation dose, total dose, solute feed rate and concentration and liquid N 2 volume were investigated. NH 3 was found to be the major N-containing product in the alkane solute system. N 2 and HC radical addition was found to be the predominate initial reaction for nitrogeneous product formation. Results of scavenger studies indicate that excited N 2 played a lesser role in precursor formation. All product yields were found to be dependent upon the H-containing species availability in the liquid N 2 solution. Production rates were limited by HC solubility. The use of the transition metal oxide supported catalyst greatly increased product formation in all systems. Product yields were found to be dependent upon the available catalyst surface area, metal loading, and reduction techniques for each metal examined. As evidenced by the radiation lag time studies, the stability of the N 2 precursors on the catalyst surface was believed to be a significant factor in reaction enhancement. Energy transfer from the catalyst to the absorbates was examined and could not be ruled out

  5. Performance of miniature electromagnetic pump at liquid nitrogen temperature; Kogata deji ponpu no ekitai chiso ondo ni okeru seino

    Energy Technology Data Exchange (ETDEWEB)

    Nagashima, K.; Herai, T. [Railway Technical Research Inst., Tokyo (Japan)

    1999-11-10

    Though it cools the radiant heat shield board of superconducting magnet for levitation system railway by the liquid nitrogen, the piping on the shield board must be made to circulate the refrigerant in order to maintain the large area, which covers superconducting coil at the uniform temperature. Though as a circulating pump, it had developed thermal pumps using the heater and systems using natural circulation, etc. until now, it examined circulation performance of liquid nitrogen using the electromagnetic pump that here, it was small, and that to do the operation is sure. (NEDO)

  6. Liquid nitrogen or phenolization for giant cell tumor of bone?: a comparative cohort study of various standard treatments at two tertiary referral centers.

    Science.gov (United States)

    van der Heijden, Lizz; van der Geest, Ingrid C M; Schreuder, H W Bart; van de Sande, Michiel A J; Dijkstra, P D Sander

    2014-03-05

    The rate of recurrence of giant cell tumor of bone is decreased by use of adjuvant treatments such as phenol, liquid nitrogen, or polymethylmethacrylate (PMMA) during curettage. We assessed recurrence and complication rates and functional outcome after curettage with use of phenol and PMMA, liquid nitrogen and PMMA, and liquid nitrogen and bone grafts. We retrospectively compared the relative effectiveness of treatment of giant cell tumors of bone at two tertiary centers with a regional function from 1990 to 2010. The 132 (of 201) patients who met the inclusion criteria had a mean age of thirty-three years (range, eleven to sixty-nine years). Treatment assignment depended purely on the center, with primary treatment consisting of curettage with use of phenol and PMMA (n = 82) at one center and with use of either liquid nitrogen and PMMA (n = 26) or liquid nitrogen and bone grafts (n = 24) at the other center. Recurrence and complication rates were determined, and functional outcome was assessed on the basis of the Musculoskeletal Tumor Society (MSTS) score. The mean duration of follow-up was eight years (range, two to twenty-two years). Recurrence rates were comparable among the groups (28% for phenol and PMMA, 31% for liquid nitrogen and PMMA, and 38% for liquid nitrogen and bone grafts; p = 0.52). Soft-tissue extension increased the recurrence risk (hazard ratio [HR] = 2.1, 95% confidence interval [CI] = 1.1 to 4.0, p = 0.024). The complication rate was 33% after use of liquid nitrogen and bone grafts, 27% after liquid nitrogen and PMMA, and 11% after phenol and PMMA (p = 0.019); complications included osteoarthritis, infection, postoperative fracture, nonunion, transient nerve palsy, and PMMA leakage. The complication risk was increased by the presence of a pathologic fracture (HR = 4.1, 95% CI = 1.7 to 9.5, p = 0.001) and use of liquid nitrogen (HR = 3.9, 95% CI = 1.5 to 10, p = 0.006 for liquid nitrogen and bone grafts; HR = 3.1, 95% CI = 1.1 to 8.6, p = 0

  7. CARR-CNS with crescent-shape moderator cell and sub-cooling helium jacket around cell

    International Nuclear Information System (INIS)

    Yu, Qingfeng; Feng, Quanke; Kawai, Takeshi; Cheng, Liang; Shen, Feng; Yuan, Luzheng

    2005-01-01

    The new type of the moderator cell was developed for the Cold Neutron Source (CNS) of the China Advanced Research Reactor (CARR) which is now constructing at the China Institute of Atomic Energy in Beijing. A crescent-shape moderator cell covered by the sub-cooling helium jacket is adopted. A crescent-shape would help to increase the volume of the moderator cell for corresponding it to the 4 cold neutron guide tubes, even if liquid hydrogen not liquid deuterium were used as a cold moderator. The sub-cooling helium jacket covering the moderator cell removes the nuclear heating of the outer shell wall of the cell. It contributes to reduce the void fraction of liquid hydrogen in the inner shell. Such a type of a moderator cell is suitable for the CNS with higher nuclear heating. The cold helium gas flows down firstly into the sub-cooling helium jacket and then flows up to the condenser. Therefore, the theory of the self-regulation for the thermo-siphon type of the CNS is also applicable

  8. Strength analysis of CARR-CNS with crescent-shape moderator cell and helium sub-cooling jacket covering cell

    International Nuclear Information System (INIS)

    Yu Qingfeng; Feng Quanke; Kawai Takeshi; Shen Feng; Yuan Luzheng; Cheng Liang

    2005-01-01

    The new type of the moderator cell was developed for the cold neutron source (CNS) of the China Advanced Research Reactor (CARR) which is now being constructed at the China Institute of Atomic Energy in Beijing. A crescent-shape moderator cell covered by the helium sub-cooling jacket is adopted. The structure of the moderator cell is optimized by the stress FEM analysis. A crescent-shape would help to increase the volume of the moderator cell for fitting it to the four cold neutron guide tubes, even if liquid hydrogen, not liquid deuterium, was used as a cold moderator. The helium sub-cooling jacket covering the moderator cell removes the nuclear heating of the outer shell wall of the cell. It contributes to reduce the void fraction of liquid hydrogen in the outer shell of the moderator cell. Such a type of a moderator cell is suitable for the CNS with higher nuclear heating. The cold helium gas flows down first into the helium sub-cooling jacket and then flows up to the condenser. The theory of the self-regulation suitable to the thermo-siphon type of the CNS is also applicable and validated

  9. CARR-CNS with crescent-shape moderator cell and sub-cooling helium jacket surrounding cell

    International Nuclear Information System (INIS)

    Yu, Qingfeng; Feng, Quanke; Kawai, Takeshi; Shen, Feng; Yuan, Luzheng

    2005-01-01

    The new type of the moderator cell was developed for the Cold Neutron Source (CNS) of the China Advanced Research Reactor (CARR) which is now constructing at the China Institute of Atomic Energy in Beijing. A crescent-shape moderator cell covered by the sub-cooling helium jacket is adopted. A crescent-shape would help to increase the volume of the moderator cell for corresponding it to the 4 cold neutron guide tubes, even if liquid hydrogen not liquid deuterium were used as a cold moderator. The sub-cooling helium jacket covering the moderator cell removes the nuclear heating of the outer shell wall of the cell. It contributes to reduce the void fraction of liquid hydrogen in the inner shell. Such a type of a moderator cell is suitable for the CNS with higher nuclear heating. The cold helium gas flows down firstly into the sub-cooling helium jacket and then flows up to the condenser. Therefore, the theory of the self-regulation for the thermo-siphon type of the CNS is also applicable

  10. Determination of desipramine in biological samples using liquid-liquid-liquid microextraction combined with in-syringe derivatization, gas chromatography, and nitrogen/phosphorus detection.

    Science.gov (United States)

    Saraji, Mohammad; Mehrafza, Narges; Bidgoli, Ali Akbar Hajialiakbari; Jafari, Mohammad Taghi

    2012-10-01

    A method was established for the determination of desipramine in biological samples using liquid-liquid-liquid microextraction followed by in-syringe derivatization and gas chromatography-nitrogen phosphorus detection. The extraction method was based on the use of two immiscible organic solvents. n-Dodecane was impregnated in the pores of the hollow fiber and methanol was placed inside the lumen of the fiber as the acceptor phase. Acetic anhydride was used as the reagent for the derivatization of the analyte inside the syringe barrel. Parameters that affect the extraction efficiency (composition of donor and acceptor phase, ionic strength, sample temperature, and extraction time) as well as derivatization efficiency (amount of acetic anhydride and reaction time and temperature) were investigated. The limit of detection was 0.02 μg/L with intra and interday RSDs of 2.6 and 7.7%, respectively. The linearity of the method was in the range of 0.2-20 μg/L (r(2) = 0.9986). The method was successfully applied to determine desipramine in human plasma and urine. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Methods for applying microchannels to separate methane using liquid absorbents, especially ionic liquid absorbents from a mixture comprising methane and nitrogen

    Science.gov (United States)

    Tonkovich, Anna Lee Y [Dublin, OH; Litt, Robert D [Westerville, OH; Dongming, Qiu [Dublin, OH; Silva, Laura J [Plain City, OH; Lamont, Micheal Jay [Plain City, OH; Fanelli, Maddalena [Plain City, OH; Simmons, Wayne W [Plain city, OH; Perry, Steven [Galloway, OH

    2011-10-04

    Methods of using microchannel separation systems including absorbents to improve thermal efficiency and reduce parasitic power loss. Energy is typically added to desorb methane and then energy or heat is removed to absorb methane using a working solution. The working solution or absorbent may comprise an ionic liquid, or other fluids that demonstrate a difference in affinity between methane and nitrogen in a solution.

  12. Mathematical prediction of freezing times of bovine semen in straws placed in static vapor over liquid nitrogen.

    Science.gov (United States)

    Santos, M V; Sansinena, M; Zaritzky, N; Chirife, J

    2013-02-01

    A widespread practice in cryopreservation is to freeze spermatozoa by suspending the straws in stagnant nitrogen vapor over liquid nitrogen (N(2)V/LN(2)) for variable periods of time before plunging into liquid nitrogen (-196°C) for indefinite storage. A mathematical heat transfer model was developed to predict freezing times (phase change was considered) required for bull semen and extender packaged in 0.5ml plastic straws and suspended in static liquid nitrogen vapor. Thermophysical properties (i.e. thermal conductivity, specific heat, density, initial freezing temperature) of bovine semen and extender as a function of temperature were determined considering the water change of phase. The non-stationary heat transfer partial differential equations with variable properties (nonlinear mathematical problem) were numerically solved considering in series thermal resistances (semen suspension-straw) and the temperature profiles were obtained for both semen suspension and plastic straw. It was observed both the external heat transfer coefficient in stagnant nitrogen vapor and its temperature (controlled by the distance from the surface of liquid nitrogen to the straw) affected freezing times. The accuracy of the model to estimate freezing times of the straws was further confirmed by comparing with experimental literature data. Results of this study will be useful to select "safe" holding times of bull semen in plastic straws placed N(2)V/LN(2) to ensure that complete freezing of the sample has occurred in the nitrogen vapor and avoid cryodamage when plunging in LN(2). Freezing times predicted by the numerical model can be applied to optimize freezing protocols of bull semen in straws. Copyright © 2012 Elsevier Inc. All rights reserved.

  13. Process configuration of Liquid-nitrogen Energy Storage System (LESS) for maximum turnaround efficiency

    Science.gov (United States)

    Dutta, Rohan; Ghosh, Parthasarathi; Chowdhury, Kanchan

    2017-12-01

    Diverse power generation sector requires energy storage due to penetration of variable renewable energy sources and use of CO2 capture plants with fossil fuel based power plants. Cryogenic energy storage being large-scale, decoupled system with capability of producing large power in the range of MWs is one of the options. The drawback of these systems is low turnaround efficiencies due to liquefaction processes being highly energy intensive. In this paper, the scopes of improving the turnaround efficiency of such a plant based on liquid Nitrogen were identified and some of them were addressed. A method using multiple stages of reheat and expansion was proposed for improved turnaround efficiency from 22% to 47% using four such stages in the cycle. The novelty here is the application of reheating in a cryogenic system and utilization of waste heat for that purpose. Based on the study, process conditions for a laboratory-scale setup were determined and presented here.

  14. Rapid hydrogen hydrate growth from non-stoichiometric tuning mixtures during liquid nitrogen quenching.

    Science.gov (United States)

    Grim, R Gary; Kerkar, Prasad B; Sloan, E Dendy; Koh, Carolyn A; Sum, Amadeu K

    2012-06-21

    In this study the rapid growth of sII H(2) hydrate within 20 min of post formation quenching towards liquid nitrogen (LN(2)) temperature is presented. Initially at 72 MPa and 258 K, hydrate samples would cool to the conditions of ~60 MPa and ~90 K after quenching. Although within the stability region for H(2) hydrate, new hydrate growth only occurred under LN(2) quenching of the samples when preformed hydrate "seeds" of THF + H(2) were in the presence of unconverted ice. The characterization of hydrate seeds and the post-quenched samples was performed with confocal Raman spectroscopy. These results suggest that quenching to LN(2) temperature, a common preservation technique for ex situ hydrate analysis, can lead to rapid unintended hydrate growth. Specifically, guest such as H(2) that may otherwise need sufficiently long induction periods to nucleate, may still experience rapid growth through an increased kinetic effect from a preformed hydrate template.

  15. Mechanical characterization of selected adhesives and bulk materials at liquid nitrogen and room temperatures

    International Nuclear Information System (INIS)

    Fitzpatrick, C.M.; Stoddart, W.C.T.

    1977-01-01

    This paper presents the results of a series of mechanical tests on selected adhesives and bulk materials. The materials tested are of general interest to designers of magnets for cryogenic service and include several epoxies, a varnish, a B-stage glass cloth, insulation papers, and commercially available fiber-reinforced composites. These tests were performed at room temperature (293 K) and at liquid nitrogen temperature (77 K). The tests include both simple tension tests and lap shear tests with various adherends. The parameters critical to tensile or bond strength were varied as part of the test program. The procedures used to manufacture and test these specimens and the results of the tests are reported in this paper

  16. Device for the crystallographic study of substances maintained at liquid nitrogen temperature

    International Nuclear Information System (INIS)

    Pluchery, M.; Debrenne, P.

    1961-01-01

    When a substance to be studied has been submitted to a processing at low temperature, and that no heating can be tolerated between this processing and the X-ray investigation, conventional low temperature devices are difficult to use. Diffraction lines are recorded, as well as Bragg angles between 55 and 88 deg. The authors present a device that allows a sample permanently immersed in liquid nitrogen to be studied, either through its lower part, or as a whole. They describe the operation principle, how a sample is set into place, how measurements are performed. They comment technical characteristics and performance. This device has been used to measure parameters of graphite irradiated at high temperature [fr

  17. Deformation behavior of human dentin in liquid nitrogen: a diametral compression test.

    Science.gov (United States)

    Zaytsev, Dmitry; Panfilov, Peter

    2014-09-01

    Contribution of the collagen fibers into the plasticity of human dentin is considered. Mechanical testing of dentin at low temperature allows excluding the plastic response of its organic matrix. Therefore, deformation and fracture behavior of the dentin samples under diametral compression at room temperature and liquid nitrogen temperature are compared. At 77K dentin behaves like almost brittle material: it is deformed exclusively in the elastic regime and it fails due to growth of the sole crack. On the contrary, dentin demonstrates the ductile response at 300K. There are both elastic and plastic contributions in the deformation of dentin samples. Multiple cracking and crack tip blunting precede the failure of samples. Organic phase plays an important role in fracture of dentin: plasticity of the collagen fibers could inhibit the crack growth. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Air conditioning and power generation for residential applications using liquid nitrogen

    International Nuclear Information System (INIS)

    Ahmad, Abdalqader; Al-Dadah, Raya; Mahmoud, Saad

    2016-01-01

    Highlights: • Using liquid nitrogen to provide power and air conditioning for domestic applications. • The proposed system leads to save energy and reduce the peak electricity demands. • Compared with conventional AC saving up to 36% was achieved at the current LN2 price. • The widespread of this technology leads to lower LN2 price and saving up to 81%. • The last configuration was the efficient system with overall thermal efficiency 74%. - Abstract: Current air conditioning (AC) systems consume a significant amount of energy, particularly during peak times where most electricity suppliers face difficulties to meet the users’ demands, and the global demands for AC systems have increased rapidly over the last few decades leading to significant power consumption and carbon dioxide emissions. This paper presents a new technique that uses liquid nitrogen (LN2) produced from renewable energy sources, or surplus electricity at off peak times, to provide cooling and power for domestic houses. Thermodynamic analyses of various cryogenic cycles have been carried out to achieve the most effective configuration that produces the maximum power output with minimum LN2 flow rate, to meet the required cooling of a 170 m"2 dwelling in Libya. A comparison with a conventional AC system was also made. Results showed that at the current LN2 prices, using LN2 to provide cooling and power demands of residential buildings is feasible and saves up to 36% compared to conventional air conditioning systems with an overall thermal efficiency of 74%. However, as the LN2 price decreases to around 1.3 pence per kg, the proposed technology will have significant advantages compared to conventional AC systems with savings of up to 81%.

  19. Knee joint preservation surgery in osteosarcoma using tumour-bearing bone treated with liquid nitrogen.

    Science.gov (United States)

    Higuchi, Takashi; Yamamoto, Norio; Nishida, Hideji; Hayashi, Katsuhiro; Takeuchi, Akihiko; Kimura, Hiroaki; Miwa, Shinji; Inatani, Hiroyuki; Shimozaki, Shingo; Kato, Takashi; Aoki, Yu; Abe, Kensaku; Taniguchi, Yuta; Tsuchiya, Hiroyuki

    2017-10-01

    To preserve the joint structure in order to maintain good limb function in patients with osteosarcoma, we perform epiphyseal or metaphyseal osteotomy and reconstruction using frozen autografts that contain a tumour treated with liquid nitrogen. There are two methods of using liquid nitrogen-treated autografts: the free-freezing method and the pedicle-freezing method. The purpose of this study was to evaluate the results of intentional joint-preserving reconstruction using the free-freezing method and the pedicle-freezing method in patients with osteosarcoma. Between 2006 and 2014, we performed joint-preserving surgery (12 with the free-freezing method and six with the pedicle freezing method) to treat 18 cases of osteosarcoma (12 distal femurs and six proximal tibias) in patients who had achieved a good response to neoadjuvant chemotherapy. Among the 18 patients (nine boys and nine girls) who had a mean age of 11.6 years, 13 remained continuously disease-free, three showed no evidence of disease, one was alive with the disease, and one died from the disease. Functional outcomes were assessed as excellent in 15 patients and poor in three, with a mean follow-up period of 46.1 months. The mean Musculoskeletal Tumour Society (MSTS) score was 90.2%. Except for one patient who underwent amputation, all patients could bend their knee through >90° flexion, and nine achieved full ROM. All but two patients could walk without aid, and 11 were able to run normally throughout the follow-up period. No intraoperative complications were observed, such as surrounding soft-tissue damage, neurovascular injury, or recurrence from frozen bone. Joint-preserving reconstruction using frozen autografts yielded excellent function in patients with osteosarcoma.

  20. Feasibility of liquid nitrogen cryotherapy after failed radiofrequency ablation for Barrett's esophagus.

    Science.gov (United States)

    Trindade, Arvind J; Inamdar, Sumant; Kothari, Shivangi; Berkowitz, Joshua; McKinley, Matthew; Kaul, Vivek

    2017-09-01

    Radiofrequency ablation (RFA) for dysplastic Barrett's esophagus (BE) is highly effective. RFA failures are infrequent but can be a challenging cohort to manage. There are limited data on the feasibility of liquid nitrogen cryospray ablation for complete eradication of dysplasia (CE-D) and/or intestinal metaplasia (CE-IM) after RFA has failed to achieve CE-IM in patients with dysplastic BE. This is a retrospective review from two medical centers of prospectively maintained databases looking at patients that underwent liquid nitrogen cryospray ablation for refractory intestinal metaplasia post failed RFA. Eighteen patients were identified that met inclusion criteria. Eleven patients had persistent dysplasia and IM following RFA and seven had persistent non-dysplastic IM. More than 80% of patients were male with long-segment BE (median length 8 cm). Seventy two percent of patients with dysplasia achieved CE-D after cryotherapy. Fifty percent (9/18) of all RFA failures achieved CE-IM with cryotherapy. In comparison, RFA has a CE-IM of 78% in a less challenging treatment naïve cohort from a large-scale meta-analysis of 3802 patients. No adverse events occurred in our cohort. Cryospray ablation is feasible and safe for achieving CE-D and CE-IM after RFA failure. The CE-D rates are high with cryotherapy in this population. CE-IM with cryotherapy is acceptable in this difficult-to-treat cohort when compared to CE-IM rates with RFA in dysplastic BE treatment naïve patients (50% vs 78%). © 2017 Japan Gastroenterological Endoscopy Society.

  1. Interferometric and numerical study of the temperature field in the boundary layer and heat transfer in subcooled flow boiling

    Energy Technology Data Exchange (ETDEWEB)

    Lucic, Anita; Emans, Maximilian; Mayinger, Franz; Zenger, Christoph

    2004-04-01

    An interferometric study and a numerical simulation are presented of the combined process of the bulk turbulent convection and the dynamic of a vapor bubble which is formed in the superheated boundary layer of a subcooled flowing liquid, in order to determine the heat transfer to the flowing subcooled liquid. In this investigation focus has been given on a single vapor bubble at a defined cavity site to provide reproducible conditions. In the experimental study single bubbles were generated at a single artificial cavity by means of a CO{sub 2}-laser as a spot heater at a uniformly heated wall of a vertical rectangular channel with water as the test fluid. The experiments were performed at various degrees of subcooling and mass flow rates. The bubble growth and the temporal decrease of the bubble volume were captured by means of the high-speed cinematography. The thermal boundary layer and the temperature field at the phase-interface between fluid and bubble were visualized by means of the optical measurement method holographic interferometry with a high temporal and spatial resolution, and thus the local and temporal heat transfer could be quantified. The experimental results form a significant data basis for the description of the mean as well as the local heat transfer as a function of the flow conditions. According to the experimental configuration and the obtained data the numerical simulations were performed. A numerical method has been developed to simulate the influence of single bubbles on the surrounding fluid which is based on a Lagrangian approach to describe the motion of the bubbles. The method is coupled to a large-eddy simulations by the body force term which is locally evaluated based on the density field. The obtained experimental data correspond well with the numerical predictions, both of which demonstrate the thermo- and fluiddynamic characteristics of the interaction between the vapor bubble and the subcooled liquid.

  2. Interferometric and numerical study of the temperature field in the boundary layer and heat transfer in subcooled flow boiling

    International Nuclear Information System (INIS)

    Lucic, Anita; Emans, Maximilian; Mayinger, Franz; Zenger, Christoph

    2004-01-01

    An interferometric study and a numerical simulation are presented of the combined process of the bulk turbulent convection and the dynamic of a vapor bubble which is formed in the superheated boundary layer of a subcooled flowing liquid, in order to determine the heat transfer to the flowing subcooled liquid. In this investigation focus has been given on a single vapor bubble at a defined cavity site to provide reproducible conditions. In the experimental study single bubbles were generated at a single artificial cavity by means of a CO 2 -laser as a spot heater at a uniformly heated wall of a vertical rectangular channel with water as the test fluid. The experiments were performed at various degrees of subcooling and mass flow rates. The bubble growth and the temporal decrease of the bubble volume were captured by means of the high-speed cinematography. The thermal boundary layer and the temperature field at the phase-interface between fluid and bubble were visualized by means of the optical measurement method holographic interferometry with a high temporal and spatial resolution, and thus the local and temporal heat transfer could be quantified. The experimental results form a significant data basis for the description of the mean as well as the local heat transfer as a function of the flow conditions. According to the experimental configuration and the obtained data the numerical simulations were performed. A numerical method has been developed to simulate the influence of single bubbles on the surrounding fluid which is based on a Lagrangian approach to describe the motion of the bubbles. The method is coupled to a large-eddy simulations by the body force term which is locally evaluated based on the density field. The obtained experimental data correspond well with the numerical predictions, both of which demonstrate the thermo- and fluiddynamic characteristics of the interaction between the vapor bubble and the subcooled liquid

  3. Integrated design of cryogenic refrigerator and liquid-nitrogen circulation loop for HTS cable

    Science.gov (United States)

    Chang, Ho-Myung; Ryu, Ki Nam; Yang, Hyung Suk

    2016-12-01

    A new concept of cryogenic cooling system is proposed and investigated for application to long-length HTS cables. One of major obstacles to the cable length of 1 km or longer is the difficulty in circulating liquid nitrogen (LN) along the cables, since the temperature rise and pressure drop of LN flow could be excessively large. This study attempts a breakthrough by integrating the refrigerator with the LN circulation loop in order to eliminate the cryogenic LN pumps, and generate a large LN flow with the power of compressors at ambient temperature. A variety of thermodynamic structures are investigated on standard and modified Claude cycles, where nitrogen is used as refrigerant and the LN circulation loop is included as part of the closed cycle. Four proposed cycles are fully analyzed and optimized with a process simulator (Aspen HYSYS) to evaluate the FOM (figure of merit) and examine the feasibility. The modified dual-pressure cycle cooled with expander stream is recommended for long HTS cables.

  4. [Simultaneous determination of four common nonprotein nitrogen substances in urine by high performance liquid chromatography].

    Science.gov (United States)

    Ma, Yuhua; Huang, Dongqun; Zhang, Rui; Xu, Shiru; Feng, Shun

    2013-11-01

    A high performance liquid chromatographic (HPLC) method was proposed to simultaneously determine four common nonprotein nitrogen substances, including creatine (Cr), creatinine (Cn), uric acid (Ua) and pseudouridine (Pu) in urine. After proteins being removed by acetone precipitation method, freeze drying and redissolving, the urine samples were analyzed by HPLC. Chromatographic separation was performed on a Waters RP18 Column (150 mm x 4.60 mm, 3.5 microm) in gradient elution mode using 10.0 mmol/L KH2PO4 solution (pH 4.78) and acetonitrile as mobile phases at a flow rate of 0.8 mL/min. The samples were detected at 220 nm. Rapid separation was achieved within 7 min. Under the optimized conditions, good linearities of four common nonprotein nitrogen substances were obtained in the range of 0.1-250 mg/L. The detection limits were 9.31 (Cr), 26.19 (Cn), 4.70 (Ua), an 6.30 (Pu) microg/L and the recoveries were in the range of 81%-111% with the relative standar deviations of 0.23%-2.78% (n = 3). The results demonstrate that this method is simple, rapid and accurate with good reproducibility, and can provide early diagnosis and preliminary judgment for type 2 diabetes mellitus (T2DM) patients with renal damage.

  5. Liquid nitrogen for the treatment of actinic keratosis: a longitudinal assessment.

    Science.gov (United States)

    Ianhez, Mayra; Miot, Hélio Amante; Bagatin, Edileia

    2014-08-01

    Cryosurgery with liquid nitrogen is one of the most used treatments for actinic keratosis. We aimed to study the effectiveness of two consecutive sessions of cryosurgery for actinic keratosis and investigate factors associated with its therapeutic success. Hence, we conducted a longitudinal study including 92 patients of both sexes, aged 50-75 years with 5-50 actinic keratosis on the face and forearms, who underwent cryosurgery and treatment with sunscreen SPF 30, at baseline and after 120 days. The lesions were counted in duplicate by the same examiner before the start of treatment and after 120 (N=92) and 300 days (N=33), represented by their medians and quartiles and compared using the generalized linear mixed effects model (negative binomial). Treatment behavior was investigated in relation to sex, age, education, skin type, smoking, sun exposure at work and the use of aspirin, anti-inflammatory and angiotensin-converting enzyme inhibitors. There was a significant reduction in the actinic keratosis count on the face and forearms (pliquid nitrogen reduced the actinic keratosis count. Copyright © 2014 Elsevier Inc. All rights reserved.

  6. Straightforward single-calibrant quantification of seized designer drugs by liquid chromatography-chemiluminescence nitrogen detection.

    Science.gov (United States)

    Rasanen, Ilpo; Kyber, Marianne; Szilvay, Ilmari; Rintatalo, Janne; Ojanperä, Ilkka

    2014-04-01

    Sixty-one different psychoactive substances were quantified by liquid chromatography-chemiluminescence nitrogen detection (LC-CLND) in 177 samples, using a single secondary standard (caffeine), in a trial concerning the quantitative purity assessment of drug-related material seized by the police in 2011-2012 and customs in 2011-2013 in Finland. The substances found were predominantly substituted phenethylamines, cathinones, tryptamines and synthetic cannabinoids, which were identified by appropriate methods prior to submitting the samples for quantification by LC-CLND. The equimolarity and expanded uncertainty of measurement by LC-CLND were on average 95% and 13%, respectively, based on 16 different substances. The median (mean) purity of stimulant/hallucinogenic drug samples seized at the border was 92.9% (87.6%) and in the street 82.0% (64.5%). The corresponding figures for powdery synthetic cannabinoid samples seized at the border and in the street were 99.0% (96.8%) and 90.0% (92.2%), respectively. There was generally only one active drug to be quantified in each sample. Seized herbal samples contained 0.15-9.2% of between one and three components. LC-CLND was found to be suitable for quantification of the nitrogen-containing drugs encountered in the study, showing sufficient N-equimolarity for both stimulant/hallucinogenic drugs and synthetic cannabinoids. The technique possesses great potential as a standard technique in forensic laboratories. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  7. First 10 kg of naked Germanium detectors in liquid nitrogen installed in the GENIUS-Test-Facility

    International Nuclear Information System (INIS)

    Klapdor-Kleingrothaus, H.V.; Chkvorets, O.; Krivosheina, I.V.; Strecker, H.; Tomei, C.

    2003-01-01

    The first four naked high-purity Germanium detectors were installed successfully in liquid nitrogen in the GENIUS-Test-Facility in the GRAN SASSO Underground Laboratory on May 5, 2003. This is the first time ever that this novel technique aiming at extreme background reduction in search for rare decays is going to be tested underground. First operational parameters are presented

  8. Effect of geographical location, year and cultivar on survival of Malus sp. dormant buds stored in vapors of liquid nitrogen

    Science.gov (United States)

    Woody plant crop germplasm is often grown in different geographical locations with various climatic conditions. One of the methods of a secure back-up of tree crop is storing winter buds in liquid nitrogen. It was thought that dormant buds from colder climates would have a higher post storage surviv...

  9. Application of a Novel Liquid Nitrogen Control Technique for Heat Stress and Fire Prevention in Underground Mines.

    Science.gov (United States)

    Shi, Bobo; Ma, Lingjun; Dong, Wei; Zhou, Fubao

    2015-01-01

    With the continually increasing mining depths, heat stress and spontaneous combustion hazards in high-temperature mines are becoming increasingly severe. Mining production risks from natural hazards and exposures to hot and humid environments can cause occupational diseases and other work-related injuries. Liquid nitrogen injection, an engineering control developed to reduce heat stress and spontaneous combustion hazards in mines, was successfully utilized for environmental cooling and combustion prevention in an underground mining site named "Y120205 Working Face" (Y120205 mine) of Yangchangwan colliery. Both localized humidities and temperatures within the Y120205 mine decreased significantly with liquid nitrogen injection. The maximum percentage drop in temperature and humidity of the Y120205 mine were 21.9% and 10.8%, respectively. The liquid nitrogen injection system has the advantages of economical price, process simplicity, energy savings and emission reduction. The optimized heat exchanger used in the liquid nitrogen injection process achieved superior air-cooling results, resulting in considerable economic benefits.

  10. TEMPORARY STORAGE OF BOVINE SEMEN CRYOPRESERVED IN LIQUID NITROGEN ON DRY ICE AND REFREEZING OF FROZEN-THAWED SEMEN.

    Science.gov (United States)

    Abdussamad, A M; Gauly, M; Holtz, W

    2015-01-01

    Two experiments were conducted. The purpose of Experiment 1 was to investigate whether viability of bovine semen stored in liquid nitrogen (-196°C) will be adversely affected by temporary exposure to dry ice (-79°C). It was convincingly shown that post thaw-motility was not affected, regardless whether semen was thawed immediately or after being returned to liquid nitrogen. Shipping or temporary storage on dry ice, thus, is a viable option. In Experiment 2, refreezing of frozen-thawed semen was attempted. The proportion of motile spermatozoa was reduced by a factor of ten to between 6.0 % and 7.4 %, regardless whether thawing occurred directly after removal from liquid nitrogen or after an interim period on dry ice. When semen was refrozen on dry ice before being returned to liquid nitrogen, motility rates were significantly improved (13.0 % to 17.0 %, P<0.05). In both experiments sperm cells that remained motile displayed vigorous forward movement and normal morphological appearance.

  11. Test of Topmetal-II{sup −} in liquid nitrogen for cryogenic temperature TPCs

    Energy Technology Data Exchange (ETDEWEB)

    Zou, Shuguang; Fan, Yan; An, Mangmang; Chen, Chufeng; Huang, Guangming; Liu, Jun; Pei, Hua; Sun, Xiangming, E-mail: xmsun@phy.ccnu.edu.cn; Yang, Ping; Wang, Dong; Xiao, Le; Wang, Zhen; Wang, Kai; Zhou, Wei

    2016-09-11

    Topmetal-II{sup −} is a highly pixelated direct charge sensor that contains a 72×72 pixel array of 83 μm pitch size. The key feature of Topmetal-II{sup −} is that it can directly collect charges via metal nodes of each pixel to form two-dimensional images of charge cloud distributions. Topmetal-II{sup −} was proved to measure charged particles without amplification at room temperature. To measure its performance at cryogenic temperature, a Topmetal-II{sup −} sensor is embedded into a liquid nitrogen dewar. The results presented in this paper show that Topmetal-II{sup −} can also operate well at this low temperature with a noise (ENC) of 12 e{sup −} lower than that at room temperature (13 e{sup −}). From the noise perspective, Topmetal-II{sup −} is a promising candidate for the next generation readout of liquid argon and xenon time projection chamber (TPC) used in experiments searching for neutrinoless double beta decay and dark matter.

  12. CFD simulation of subcooled flow boiling at low pressure

    International Nuclear Information System (INIS)

    Koncar, B.; Mavko, B.

    2001-01-01

    An increased interest to numerically simulate the subcooled flow boiling at low pressures (1 to 10 bar) has been aroused in recent years, pursued by the need to perform safety analyses of research nuclear reactors and to investigate the sump cooling concept for future light water reactors. In this paper the subcooled flow boiling has been simulated with a multidimensional two-fluid model used in a CFX-4.3 computational fluid dynamics (CFD) code. The existing model was adequately modified for low pressure conditions. It was shown that interfacial forces, which are usually used for adiabatic flows, need to be modeled to simulate subcooled boiling at low pressure conditions. Simulation results are compared against published experimental data [1] and agree well with experiments.(author)

  13. influence of sub-cooling on the energy performance of two eco

    African Journals Online (AJOL)

    PUBLICATIONS1

    frigerants, consistently exhibited better performance than R22 in sub-cooling heat ... 2014 Kwame Nkrumah University of Science and Technology (KNUST) ... sales volume among all refrigerants. .... The sub-cooling heat exchanger affects the.

  14. Recovery of nitrogen and phosphorus from alkaline fermentation liquid of waste activated sludge and application of the fermentation liquid to promote biological municipal wastewater treatment.

    Science.gov (United States)

    Tong, Juan; Chen, Yinguang

    2009-07-01

    In previous publications we reported that by controlling the pH at 10.0 the accumulation of short-chain fatty acids (SCFA) during waste activated sludge (WAS) fermentation was remarkably improved [Yuan, H., Chen, Y., Zhang, H., Jiang, S., Zhou, Q., Gu, G., 2006. Improved bioproduction of short-chain fatty acids (SCFAs) from excess sludge under alkaline conditions. Environ. Sci. Technol. 40, 2025-2029], but significant ammonium nitrogen (NH(4)-N) and soluble ortho-phosphorus (SOP) were released [Chen, Y., Jiang, S., Yuan, H., Zhou, Q., Gu, G., 2007. Hydrolysis and acidification of waste activated sludge at different pHs. Water Res. 41, 683-689]. This paper investigated the simultaneous recovery of NH(4)-N and SOP from WAS alkaline fermentation liquid and the application of the fermentation liquid as an additional carbon source for municipal wastewater biological nitrogen and phosphorus removal. The central composite design (CCD) of the response surface methodology (RSM) was employed to optimize and model the simultaneous NH(4)-N and SOP recovery from WAS alkaline fermentation liquid. Under the optimum conditions, the predicted and experimental recovery efficiency was respectively 73.4 and 75.7% with NH(4)-N, and 82.0 and 83.2% with SOP, which suggested that the developed models described the experiments well. After NH(4)-N and SOP recovery, the alkaline fermentation liquid was added to municipal wastewater, and the influence of volume ratio of fermentation liquid to municipal wastewater (FL/MW) on biological nitrogen and phosphorus removal was investigated. The addition of fermentation liquid didn't significantly affect nitrification. Both SOP and total nitrogen (TN) removal were increased with fermentation liquid, but there was no significant increase at FL/MW greater than 1/35. Compared to the blank test, the removal efficiency of SOP and TN at FL/MW=1/35 was improved from 44.0 to 92.9%, and 63.3 to 83.2%, respectively. The enhancement of phosphorus and nitrogen

  15. Use of highly pressurized liquid nitrogen technology for concrete scabbling application at SICN nuclear facility - 59282

    International Nuclear Information System (INIS)

    Moggia, Fabrice; Vaudey, Claire-Emilie; Damerval, Frederique; Varet, Thierry; Toulemonde, Valerie; Richard, Frederic; Anderson, Gary

    2012-01-01

    The decommissioning process is a quite long and complicated stage who may take few years or decades to be achieved. Generally, this process involves the implementation of a large number of technologies dedicated to cutting and decontamination operations. Based on this finding, the Clean- Up Business Unit of AREVA with Air Liquide decided to start the development of a new technology based on the use of liquid nitrogen (-140 deg. C / 3500 bar). The NitroJet R process is a quite interesting and promising technology. It can be used, as we described in this document, for concrete scabbling operations but also for decontamination and cutting applications. The Clean-Up Business Unit, with its partner Air Liquide, realized a complete study of this technology including several tests and optimizations to be able to handle it in a nuclear environment. Thus, we did: - increase of the reliability of the machine, - nuclearization of the system (including the development of efficient shroud system and efficient HP pipes insulation); - development of a dedicated bearer for automatic configuration; - optimization of parameters for D and D applications. As we already mentioned, NitroJet R technology showed promising perspectives as: - economic: increase of rate processing, decrease in site monitoring costs, - environmental: use of an inert gas, no secondary waste generation, non use of chemical, dry process, - social: less strenuous work, decrease of operator dosimetry compatible with ALARA principle The future for the NitroJet R technology will be its implementation in a real high level activity environment. This process will be used in spring 2012 in AREVA nuclear reprocessing facility of La Hague (France) to accomplish concrete scabbling applications. This test will be the last of a long development period before industrial exploitation. (authors)

  16. A Comparative Study of Liquid Nitrogen Cryotherapy as Monotherapy versus in Combination with Podophyllin in the Treatment of Condyloma Acuminata.

    Science.gov (United States)

    Sharma, Nidhi; Sharma, Sanjeev; Singhal, Chetna

    2017-03-01

    Condyloma Acuminata (CA) is a common viral sexually transmitted disease. Although various treatment modalities are available for treating CA, but none of them can achieve 100% response rate. In a search for better response rate and less recurrence rate, the combination of cytotoxic agent Podophyllin with ablative liquid nitrogen cryotherapy was evaluated over cryotherapy alone. To evaluate the synergistic effect of Podophyllin as a chemotherapeutic adjunct to an ablative therapy of liquid nitrogen cryotherapy versus liquid nitrogen cryotherapy alone in the treatment of CA. Sixty patients with multiple CA were randomly assigned to two groups in the study. Thirty patients in group A received double freeze thaw cycle of 25 seconds of liquid nitrogen cryotherapy. Thirty patients in Group B were subjected to liquid nitrogen cryotherapy in a similar manner followed by application of not more than 0.5 ml of 25% Podophyllin solution. All patients were followed up at 1, 4, 8, 12 and 24 weeks after the treatment to monitor the response to therapy and evaluation for any recurrence. When the number of unresponsive lesions were more than 30% of original lesions at 4 weeks follow-up, then the whole procedure was repeated again. The complete response rate and the recurrence rate in the Group B in our study were comparable to Group A as the difference was statistically insignificant. But the differentiating point was that the similar results were obtained in Group B with an average1.2 sessions per patient in comparison to an average of 1.67 sessions per patient in Group A. Cryotherapy represents a simple, safe and effective regimen for the treatment of multiple CA which in combination with Podophyllin is even more effective as a single session procedure; thereby shortening the treatment regimen.

  17. Nitrogen

    Science.gov (United States)

    Apodaca, L.E.

    2010-01-01

    Ammonia was produced by 13 companies at 23 plants in 16 states during 2009. Sixty percent of all U.S. ammonia production capacity was centered in Louisiana. Oklahoma and Texas because of those states' large reserves of natural gas, the dominant domestic feedstock. In 2009, U.S. producers operated at about 83 percent of their rated capacity (excluding plants that were idle for the entire year). Five companies — Koch Nitrogen Co.; Terra Industries Inc.; CF Industries Inc.; PCS Nitrogen Inc. and Agrium Inc., in descending order — accounted for 80 percent of the total U.S. ammonia production capacity. U.S. production was estimated to be 7.7 Mt (8.5 million st) of nitrogen (N) content in 2009 compared with 7.85 Mt (8.65 million st) of N content in 2008. Apparent consumption was estimated to have decreased to 12.1 Mt (13.3 million st) of N, a 10-percent decrease from 2008. The United States was the world's fourth-ranked ammonia producer and consumer following China, India and Russia. Urea, ammonium nitrate, ammonium phosphates, nitric acid and ammonium sulfate were the major derivatives of ammonia in the United States, in descending order of importance.

  18. Nitrogen-doped carbon capsules via poly(ionic liquid)-based layer-by-layer assembly.

    Science.gov (United States)

    Zhao, Qiang; Fellinger, Tim-Patrick; Antonietti, Markus; Yuan, Jiayin

    2012-07-13

    Layer-by-layer (LbL) assembly technique is applied for the first time for the preparation of nitrogen-doped carbon capsules. This approach uses colloid silica as template and two polymeric deposition components, that is, poly(ammonium acrylate) and a poly (ionic liquid) poly(3-cyanomethyl-1-vinylimidazolium bromide), which acts as both the carbon precursor and nitrogen source. Nitrogen-doped carbon capsules are prepared successfully by polymer wrapping, subsequent carbonization and template removal. The as-synthesized carbon capsules contain ≈7 wt% of nitrogen and have a structured specific surface area of 423 m(2) g(-1). Their application as supercapacitor has been briefly introduced. This work proves that LbL assembly methodology is available for preparing carbon structures of complex morphology. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    Science.gov (United States)

    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.

  20. Subcooled boiling heat transfer on a finned surface

    International Nuclear Information System (INIS)

    Kowalski, J.E.; Tran, V.T.; Mills, P.J.

    1992-01-01

    Experimental and numerical studies have been performed to determine the heat transfer coefficients from a finned cylindrical surface to subcooled boiling water. The heat transfer rates were measured in an annular test section consisting of an electrically heated fuel element simulator (FES) with eight longitudinal, rectangular fins enclosed in a glass tube. A two-dimensional finite-element heat transfer model using the Galerkin method was employed to determine the heat transfer coefficients along the periphery of the FES surface. An empirical correlation was developed to predict the heat transfer coefficients during subcooled boiling. The correlation agrees well with the measured data. (6 figures) (Author)

  1. Commissioning of the Liquid Nitrogen Thermo-Siphon System for NASA-JSC Chamber-A

    Science.gov (United States)

    Homan, J.; Montz, M.; Ganni, V.; Sidi-Yekhlef, A.; Knudsen, P.; Garcia, S.; Garza, J.

    2013-01-01

    NASA's Space Environment Simulation Laboratory's (SESL) Chamber A, located at the Johnson Space Center in Houston Texas has recently implemented major enhancements of its cryogenic and vacuum systems. The new liquid nitrogen (LN2) thermo-siphon system was successfully commissioned in August of 2012. Chamber A, which has 20 K helium cryo-panels (or shrouds ) which are shielded by 80 K nitrogen shrouds, is capable of simulating a deep space environment necessary to perform ground testing of NASA s James Webb Space Telescope (JWST). Chamber A s previous system used forced flow LN2 cooling with centrifugal pumps, requiring 200,000 liters of LN2 to cool-down and consuming 180,000 liters per day of LN2 in steady operation. The LN2 system did not have the reliability required to meet the long duration test of the JWST, and the cost estimate provided in the initial approach to NASA-JSC by the sub-contractor for refurbishment of the system to meet the reliability goals was prohibitive. At NASA-JSC's request, the JLab Cryogenics Group provided alternative options in 2007, including a thermo-siphon, or natural flow system. This system, eliminated the need for pumps and used one tenth of the original control valves, relief valves, and burst disks. After the thermo-siphon approach was selected, JLab provided technical assistance in the process design, mechanical design, component specification development and commissioning oversight, while the installation and commissioning operations of the system was overseen by the Jacobs Technology/ESC group at JSC. The preliminary commissioning data indicate lower shroud temperatures, 70,000 liters to cool-down and less than 90,000 liters per day consumed in steady operation. All of the performance capabilities have exceeded the design goals. This paper will outline the comparison between the original system and the predicted results of the selected design option, and the commissioning results of thermo-siphon system.

  2. Commissioning of the Liquid Nitrogen Thermo-Siphon System for NASA-JSC Chamber A

    Science.gov (United States)

    Homan, J.; Montz, M.; Ganni, V.; Sidi-Yekhlef, A.; Knudsen, P.; Garcia, S.; Garza, J.

    2013-01-01

    NASA s Space Environment Simulation Laboratory s (SESL) Chamber A, located at the Johnson Space Center in Houston Texas has recently implemented major enhancements of its cryogenic and vacuum systems. The new liquid nitrogen (LN) thermo-siphon system was successfully commissioned in August of 2012. Chamber A, which has 20 K helium cryo-panels (or shrouds ) which are shielded by 80 K nitrogen shrouds, is capable of simulating a deep space environment necessary to perform ground testing of NASA s James Webb Space Telescope (JWST). Chamber A s previous system used forced flow LN cooling with centrifugal pumps, requiring 220,000 liters of LN to cool-down and consuming 180,000 liters per day of LN in steady operation. The LN system did not have the reliability required to meet the long duration test of the JWST, and the cost estimate provided in the initial approach to NASA-JSC by the subcontractor for refurbishment of the system to meet the reliability goals was prohibitive. At NASA-JSC s request, the JLab Cryogenics Group provided alternative options in 2007, including a thermo-siphon, or natural flow system. This system, eliminated the need for pumps and used one tenth of the original control valves, relief valves, and burst disks. After the thermo-siphon approach was selected, JLab provided technical assistance in the process design, mechanical design, component specification development and commissioning oversight, while the installation and commissioning operations of the system was overseen by the Jacobs Technology/ESC group at JSC. The preliminary commissioning data indicate lower shroud temperatures, 68,000 liters to cool-down and less than 91,000 liters per day consumed in steady operation. All of the performance capabilities have exceeded the design goals. This paper will outline the comparison between the original system and the predicted results of the selected design option, and the commissioning results of thermo-siphon system.

  3. Principle of a liquid nitrogen irradiation device and its realization for use in a swimming-pool type reactor

    International Nuclear Information System (INIS)

    Bochirol, L.; Doulat, J.; Weil, L.

    1961-01-01

    The problem of pile irradiation of samples immersed in liquid nitrogen has been solved with total elimination of explosion hazards and high reliability (no moving parts). The principle of the device is that of a double bath: one of high purity nitrogen cools the samples at the level of the core; a second of commercial nitrogen is located above the first one, outside the high radiation field, and works as a continuous condenser for the pure nitrogen, the flow-back of which is provided simply by gravity. The apparatus described in detail here has been designed for a swimming-pool pile. It was so designed as to provide absolute protection against radiations and to allow the irradiated samples to be easily removed in the cold condition. This apparatus has been in operation for several months. In a fast flux greater than 10 13 neutrons/cm 2 .s and a γ-flux of the order of 10 8 roentgens/h, the consumption of liquid nitrogen is of the order of 100 liters a day. (author) [fr

  4. Assessment of external heat transfer coefficient during oocyte vitrification in liquid and slush nitrogen using numerical simulations to determine cooling rates.

    Science.gov (United States)

    Santos, M V; Sansinena, M; Zaritzky, N; Chirife, J

    2012-01-01

    In oocyte vitrification, plunging directly into liquid nitrogen favor film boiling and strong nitrogen vaporization. A survey of literature values of heat transfer coefficients (h) for film boiling of small metal objects with different geometries plunged in liquid nitrogen revealed values between 125 to 1000 W per per square m per K. These h values were used in a numerical simulation of cooling rates of two oocyte vitrification devices (open-pulled straw and Cryotop), plunged in liquid and slush nitrogen conditions. Heat conduction equation with convective boundary condition was considered a linear mathematical problem and was solved using the finite element method applying the variational formulation. COMSOL Multiphysics was used to simulate the cooling process of the systems. Predicted cooling rates for OPS and Cryotop when cooled at -196 degree C (liquid nitrogen) or -207 degree C (average for slush nitrogen) for heat transfer coefficients estimated to be representative of film boiling, indicated lowering the cooling temperature produces only a maximum 10 percent increase in cooling rates; confirming the main benefit of plunging in slush over liquid nitrogen does not arise from their temperature difference. Numerical simulations also demonstrated that a hypothetical four-fold increase in the cooling rate of vitrification devices when plunging in slush nitrogen would be explained by an increase in heat transfer coefficient. This improvement in heat transfer (i.e., high cooling rates) in slush nitrogen is attributed to less or null film boiling when a sample is placed in slush (mixture of liquid and solid nitrogen) because it first melts the solid nitrogen before causing the liquid to boil and form a film.

  5. Direct Numerical Simulation and Visualization of Subcooled Pool Boiling

    Directory of Open Access Journals (Sweden)

    Tomoaki Kunugi

    2014-01-01

    Full Text Available A direct numerical simulation of the boiling phenomena is one of the promising approaches in order to clarify their heat transfer characteristics and discuss the mechanism. During these decades, many DNS procedures have been developed according to the recent high performance computers and computational technologies. In this paper, the state of the art of direct numerical simulation of the pool boiling phenomena during mostly two decades is briefly summarized at first, and then the nonempirical boiling and condensation model proposed by the authors is introduced into the MARS (MultiInterface Advection and Reconstruction Solver developed by the authors. On the other hand, in order to clarify the boiling bubble behaviors under the subcooled conditions, the subcooled pool boiling experiments are also performed by using a high speed and high spatial resolution camera with a highly magnified telescope. Resulting from the numerical simulations of the subcooled pool boiling phenomena, the numerical results obtained by the MARS are validated by being compared to the experimental ones and the existing analytical solutions. The numerical results regarding the time evolution of the boiling bubble departure process under the subcooled conditions show a very good agreement with the experimental results. In conclusion, it can be said that the proposed nonempirical boiling and condensation model combined with the MARS has been validated.

  6. Cavitation, subcooled boiling and a measuring method developed at ENEA

    International Nuclear Information System (INIS)

    Tirelli, D.

    1988-01-01

    A brief description of cavitation and subcooled boiling is reported; their effects, measuring methods, operating limits and prescribed standards are described. The whole, to better clarify the usefulness and the importance of a measuring instrument developed at ENEA, to study the above phenomena

  7. On subcooler design for integrated two-temperature supermarket refrigeration system

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Liang [Institute of Refrigeration and Cryogenics, Shanghai Jiaotong University, Shanghai 200240 (China); Zhang, Chun-Lu [College of Mechanical Engineering, Tongji University, No. 4800, Cao An Highway, Shanghai 201804 (China)

    2011-01-15

    The energy saving opportunity of supermarket refrigeration systems using subcooler between the medium-temperature (MT) refrigeration system and the low-temperature (LT) refrigeration system has been identified in the previous work. This paper presents a model-based comprehensive analysis on the subcooler design. The optimal subcooling control is discussed as well. With optimal subcooler size and subcooling control, the maximum energy savings of integrated two-temperature supermarket refrigeration system using R404A or R134a as working fluid can achieve 27% or 20%, respectively. The load ratio of MT to LT system and the operating conditions have considerable impact on the energy savings. (author)

  8. Experimental evaluation of local bubble parameters of subcooled boiling flow in a pressurized vertical annulus channel

    Energy Technology Data Exchange (ETDEWEB)

    Chu, In-Cheol, E-mail: chuic@kaeri.re.kr; Lee, Seung-Jun; Youn, Young Jung; Park, Jong Kuk; Choi, Hae Seob; Euh, Dong-Jin; Song, Chul-Hwa

    2017-02-15

    Experiments were performed to quantify the local bubble parameters such as void fraction, bubble velocity, interfacial area concentration, and Sauter mean diameter for the subcooled boiling flow of a refrigerant R-134a in a pressurized vertical annulus channel. Optical fiber void probe and double pressure boundary visualization windows were installed at four measurement stations with different elevations, thus enabling the quantification of local bubble parameters and observation of global boiling structure. Using high-resolution traverse systems for the optical fiber void probes and the heating tube, the radial profiles of the bubble parameters and their axial propagation can be evaluated at any elevation of the whole heating region. At this first phase of the experiments, three tests were conducted by varying the pressure, heat flux, mass flux, and local liquid subcooling. The radial profiles of the bubble parameters were obtained at seven elevations. The pressure condition of the present experiments covered the normal operating pressure of PWRs according to the similarity criteria. The present experimental data will be useful for thorough validation and improvement of the CMFD (Computation Multi-Fluid Dynamics) codes and constitutive relations.

  9. Numerical Simulation on Subcooled Boiling Heat Transfer Characteristics of Water-Cooled W/Cu Divertors

    Science.gov (United States)

    Han, Le; Chang, Haiping; Zhang, Jingyang; Xu, Tiejun

    2015-04-01

    In order to realize safe and stable operation of a water-cooled W/Cu divertor under high heating condition, the exact knowledge of its subcooled boiling heat transfer characteristics under different design parameters is crucial. In this paper, subcooled boiling heat transfer in a water-cooled W/Cu divertor was numerically investigated based on computational fluid dynamic (CFD). The boiling heat transfer was simulated based on the Euler homogeneous phase model, and local differences of liquid physical properties were considered under one-sided high heating conditions. The calculated wall temperature was in good agreement with experimental results, with the maximum error of 5% only. On this basis, the void fraction distribution, flow field and heat transfer coefficient (HTC) distribution were obtained. The effects of heat flux, inlet velocity and inlet temperature on temperature distribution and pressure drop of a water-cooled W/Cu divertor were also investigated. These results provide a valuable reference for the thermal-hydraulic design of a water-cooled W/Cu divertor. supported by the National Magnetic Confinement Fusion Science Program of China (No. 2010GB104005), Funding of Jiangsu Innovation Program for Graduate Education (CXLX12_0170), the Fundamental Research Funds for the Central Universities of China

  10. Tensile strengths of polyamide based 3D printed polymers in liquid nitrogen

    International Nuclear Information System (INIS)

    Cruz, P; Shoemake, E D; Adam, P; Leachman, J

    2015-01-01

    Advances in additive manufacturing technology have made 3D printing a viable solution for many industries, allowing for the manufacture of designs that could not be made through traditional subtractive methods. Applicability of additive manufacturing in cryogenic applications is hindered, however, by a lack of accurate material properties information. Nylon is available for printing using fused deposition modeling (FDM) and selective laser sintering (SLS). We selected 5 SLS (DuraForm® EX, DuraForm® HST, DuraForm® PA, PA 640-GSL, and PA 840-GSL) and 2 FDM (Nylon 12, ULTEM) nylon variants based on the bulk material properties and printed properties at room temperature. Tensile tests were performed on five samples of each material while immersed in liquid nitrogen at approximately 77 Kelvin. Samples were tested in XY and, where available, Z printing directions to determine influence on material properties. Results show typical SLS and FDM nylon ultimate strength retention at 77 K, when compared to (extruded or molded) nylon ultimate strength. (paper)

  11. 1000–ton testing machine for cyclic fatigue tests of materials at liquid nitrogen temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Khitruk, A. A.; Klimchenko, Yu. A.; Kovalchuk, O. A.; Marushin, E. L.; Mednikov, A. A.; Nasluzov, S. N.; Privalova, E. K.; Rodin, I. Yu.; Stepanov, D. B.; Sukhanova, M. V. [The D.V. Efremov Scientific Research Institute of Electrophysical Apparatus (NIIEFA), 3 Doroga na Metallostroy, Metallostroy, Saint Petersburg 196641 (Russian Federation)

    2014-01-29

    One of the main tasks of superconductive magnets R and D is to determine the mechanical and fatigue properties of structural materials and the critical design elements in the cryogenic temperature range. This paper describes a new facility built based on the industrial 1000-ton (10 MN) testing machine Schenk PC10.0S. Special equipment was developed to provide the mechanical and cyclic tensile fatigue tests of large-scale samples at the liquid nitrogen temperature and in a given load range. The main feature of the developed testing machine is the cryostat, in which the device converting a standard compression force of the testing machine to the tensile force affected at the test object is placed. The control system provides the remote control of the test and obtaining, processing and presentation of test data. As an example of the testing machine operation the test program and test results of the cyclic tensile fatigue tests of fullscale helium inlet sample of the PF1 coil ITER are presented.

  12. 1000–ton testing machine for cyclic fatigue tests of materials at liquid nitrogen temperatures

    International Nuclear Information System (INIS)

    Khitruk, A. A.; Klimchenko, Yu. A.; Kovalchuk, O. A.; Marushin, E. L.; Mednikov, A. A.; Nasluzov, S. N.; Privalova, E. K.; Rodin, I. Yu.; Stepanov, D. B.; Sukhanova, M. V.

    2014-01-01

    One of the main tasks of superconductive magnets R and D is to determine the mechanical and fatigue properties of structural materials and the critical design elements in the cryogenic temperature range. This paper describes a new facility built based on the industrial 1000-ton (10 MN) testing machine Schenk PC10.0S. Special equipment was developed to provide the mechanical and cyclic tensile fatigue tests of large-scale samples at the liquid nitrogen temperature and in a given load range. The main feature of the developed testing machine is the cryostat, in which the device converting a standard compression force of the testing machine to the tensile force affected at the test object is placed. The control system provides the remote control of the test and obtaining, processing and presentation of test data. As an example of the testing machine operation the test program and test results of the cyclic tensile fatigue tests of fullscale helium inlet sample of the PF1 coil ITER are presented

  13. Caution on the use of liquid nitrogen traps in stable hydrogen isotope-ratio mass spectrometry

    Science.gov (United States)

    Coplen, Tyler B.; Qi, Haiping

    2010-01-01

    An anomalous stable hydrogen isotopic fractionation of 4 ‰ in gaseous hydrogen has been correlated with the process of adding liquid nitrogen (LN2) to top off the dewar of a stainless-steel water trap on a gaseous hydrogen-water platinum equilibration system. Although the cause of this isotopic fractionation is unknown, its effect can be mitigated by (1) increasing the capacity of any dewars so that they do not need to be filled during a daily analytic run, (2) interspersing isotopic reference waters among unknowns, and (3) applying a linear drift correction and linear normalization to isotopic results with a program such as Laboratory Information Management System (LIMS) for Light Stable Isotopes. With adoption of the above guidelines, measurement uncertainty can be substantially improved. For example, the long-term (months to years) δ2H reproducibility (1& sigma; standard deviation) of nine local isotopic reference waters analyzed daily improved substantially from about 1‰ to 0.58 ‰. This isotopically fractionating mechanism might affect other isotope-ratio mass spectrometers in which LN2 is used as a moisture trap for gaseous hydrogen

  14. Angiogenic effects of cryosurgery with liquid nitrogen on the normal skin of rats, through morphometric study.

    Science.gov (United States)

    Pimentel, Camila Bianco; Moraes, Aparecida Machado de; Cintra, Maria Letícia

    2014-01-01

    Cryosurgery is an efficient therapeutic technique used to treat benign and malignant cutaneous diseases. The primary active mechanism of cryosurgery is related to vascular effects on treated tissue. After a cryosurgical procedure, exuberant granulation tissue is formed at the injection site, probably as a result of angiogenic stimulation of the cryogen and inflammatory response, particularly in endothelial cells. To evaluate the angiogenic effects of freezing, as part of the phenomenon of healing rat skin subjected to previous injury. Two incisions were made in each of the twenty rats, which were divided randomly into two groups of ten. After 3 days, cryosurgery with liquid nitrogen was performed in one of incisions. The rats' samples were then collected, cut and stained to conduct histopathological examination, to assess the local angiogenesis in differing moments and situations. It was possible to demonstrate that cryosurgery, in spite of promoting cell death and accentuated local inflammation soon after its application, induces quicker cell proliferation in the affected tissue and maintenance of this rate in a second phase, than in tissue healing without this procedure. These findings, together with the knowledge that there is a direct relationship between mononuclear cells and neovascularization (the development of a rich system of new vessels in injury caused by cold), suggest that cryosurgery possesses angiogenic stimulus, even though complete healing takes longer to occur. The significance level for statistical tests was 5% (p<0,05).

  15. Liquid nitrogen pretreatment of eucalyptus sawdust and rice hull for enhanced enzymatic saccharification.

    Science.gov (United States)

    Castoldi, Rafael; Correa, Vanesa G; de Morais, Gutierrez Rodrigues; de Souza, Cristina G M; Bracht, Adelar; Peralta, Rosely A; Peralta-Muniz Moreira, Regina F; Peralta, Rosane M

    2017-01-01

    In this work, liquid nitrogen was used for the first time in the pretreatment of plant biomasses for purposes of enzymatic saccharification. After treatment (cryocrushing), the initial rates of the enzymatic hydrolysis of eucalyptus sawdust and rice hull were increased more than ten-fold. Cryocrushing did not modify significantly the contents of cellulose, hemicellulose and lignin in both eucalyptus sawdust and rice hulls. However, substantial disorganization of the lignocellulosic materials in consequence of the pretreatment could be observed by electron microscopy. Cryocrushing was highly efficient in improving the saccharification of the holocellulose component of the plant biomasses (from 4.3% to 54.1% for eucalyptus sawdust and from 3.9% to 40.6% for rice hull). It is important to emphasize that it consists in a simple operation with low requirements of water and chemicals, no corrosion, no release of products such as soluble phenolics, furfural and hydroxymethylfurfural and no waste generation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Experimental investigations on cryogenic cooling by liquid nitrogen in the end milling of hardened steel

    Science.gov (United States)

    Ravi, S.; Pradeep Kumar, M.

    2011-09-01

    Milling of hardened steel generates excessive heat during the chip formation process, which increases the temperature of cutting tool and accelerates tool wear. Application of conventional cutting fluid in milling process may not effectively control the heat generation also it has inherent health and environmental problems. To minimize health hazard and environmental problems caused by using conventional cutting fluid, a cryogenic cooling set up is developed to cool tool-chip interface using liquid nitrogen (LN 2). This paper presents results on the effect of LN 2 as a coolant on machinability of hardened AISI H13 tool steel for varying cutting speed in the range of 75-125 m/min during end milling with PVD TiAlN coated carbide inserts at a constant feed rate. The results show that machining with LN 2 lowers cutting temperature, tool flank wear, surface roughness and cutting forces as compared with dry and wet machining. With LN 2 cooling, it has been found that the cutting temperature was reduced by 57-60% and 37-42%; the tool flank wear was reduced by 29-34% and 10-12%; the surface roughness was decreased by 33-40% and 25-29% compared to dry and wet machining. The cutting forces also decreased moderately compared to dry and wet machining. This can be attributed to the fact that LN 2 machining provides better cooling and lubrication through substantial reduction in the cutting zone temperature.

  17. Two-phase flow instability in a liquid nitrogen heat exchanger, 2

    International Nuclear Information System (INIS)

    Kondoh, Tetsuya; Fukuda, Kenji; Hasegawa, Shu; Yamada, Hidetomo; Ryu, Hiroyuki.

    1988-01-01

    Experimental and analytical investigations are conducted on flow instability in a vertically installed liquid nitrogen shell and tube type heat exchanger. The experiments are carried out by making use of water steam as a secondary fluid and it is observed that flow instability occurs in the range of small inlet flow rate. Mode analysis of the flow instability oscillation reveals that there exists a fundamental mode and its higher harmonics up to the fourth. As the period of the fundamental mode is nearly equal to the transit time for a fluid particle to travel through the heated tube, it is suggested that this flow instability is of the density wave type. It is shown that the amount of exchanged heat, as well as the pressure drop, decrease when unstable flow oscillation occurs. An analysis of the static heat transfer and pressure drop characteristics can simulate the experimental results in the stable region. Linear stability analysis is also carried out to yield the stability map as well as the period of flow oscillation, which proved to agree with the experimental data qualitatively. (author)

  18. Arcing time analysis of liquid nitrogen with respect to electrode materials

    Science.gov (United States)

    Junaid, Muhammad; Yang, Kun; Ge, Hanming; Wang, Jianhua

    2018-03-01

    Unlike sulphur hexafluoride (SF6), liquid nitrogen (LN2) is cost effective, environment friendly and cryogenic dielectric. It has astounding insulating properties with the potential to decrease power loss in switchgear applications due to its remarkably low temperatures. The basic research is however a necessity to observe the performance of LN2 subjected to high luminance arcs. So far, there are no findings that refer to the arcing time inside the LN2 environment. The objective of this work was to investigate the arcing times in LN2 and compare the results with open air conditions using different electrode materials. Experiments were conducted on different DC voltages and their arcing times were measured. Three different kinds of electrode materials, namely: pure copper (Cu), stainless used steel (SUS) and aluminium alloy (Al 6061) were tested under 1 atmospheric pressure. The results revealed that LN2 extinguishes arc in almost half the amount of time required by the open air insulation. With Al 6061 has the shortest arcing time, whilst Cu, the second best choice and SUS places last in the evaluation. It was encapsulated from the findings that LN2 is a better choice than air insulation in terms of arc quenching and a better alternative to SF6 when environment is the priority.

  19. Utilization of urea/molasses liquid feed as a major source of nitrogen and energy for lactating cows

    International Nuclear Information System (INIS)

    Ranjhan, S.K.; Krishna Mohan, D.V.G.; Pathak, N.N.

    1976-01-01

    Experiments were conducted in which urea/molasses liquid feed along with a limited amount of intact protein and cereal forage was fed to lactating cows, and compared with another group receiving conventional concentrate and roughage-based rations. Voluntary consumption of liquid feed by cows was satisfactory. There was no significant difference in the milk yield between the two groups. The higher consumption of metabolizable energy and digestible crude protein by experimental cows from liquid feed was not reflected in their milk yields or body weights. Various other parameters such as digestibilities of nutrients, efficiency of energy and nitrogen utilization for milk production and N-balance have been presented in cows fed urea/molasses liquid diets and conventional diets. (author)

  20. Removal of Basic Nitrogen Compounds from Fuel Oil with [Hnmp]H2PO4 Ionic Liquid

    Directory of Open Access Journals (Sweden)

    Z. Zhou

    2017-04-01

    Full Text Available Ionic liquid (IL N-methyl pyrrolidone dihydrogen phosphate ([Hnmp]H2PO4 was synthesized and its structure was characterized with FT-IR spectroscopy and 1H NMR. The denitrogenation performance of the ionic liquid was investigated using Fushun shale diesel oil that included 0.52 w% basic nitrogen as feedstock. Experiment results showed that under the operating conditions with temperature of 30 °C, 1:7 (w/w IL: oil, reaction time of 20 min, and settling time of 2 h, the ionic liquid exhibited good denitrogenation performance achieving 86.27 % basic N-extraction efficiency and the yield of refined diesel oil can reach more than 90 %. In addition, the basic N-removal efficiency can still reach 54 % during four recycles of the ionic liquid.

  1. Mandibular Reconstruction by Using a Liquid Nitrogen-Treated Autograft in a Dog with an Oral Tumor.

    Science.gov (United States)

    Okamura, Yasuhiko; Heishima, Kazuki; Motegi, Tomoki; Sasaki, Jun; Goryo, Masanobu; Nishida, Hideji; Tsuchiya, Hiroyuki; Katayama, Masaaki; Uzuka, Yuji

    A 10 yr old intact female German shepherd dog presented with a large peripheral odontogenic fibroma and malignant melanoma on her lower jaw. The tumor was resected with a unilateral subtotal rostral hemimandibulectomy. After the mandible was removed, it was devitalized intraoperatively by freezing it in liquid nitrogen. It was subsequently reimplanted. New bone tissue formed in the gap between the frozen bone and the host bone. The regenerated bone contained osteocytes, osteoblasts, and blood vessels. The cosmetic appearance of the dog was preserved. The dog had normal mastication. The malignant melanoma recurred rostral of the left canine tooth at 159 days after the reconstruction surgery. A subtotal hemimandibulectomy was consequently performed. This is the first reported case of mandibular reconstruction using a liquid nitrogen-treated autograft in a dog with oral tumors.

  2. A planar, solid-state amperometric sensor for nitrogen dioxide, employing an ionic liquid electrolyte contained in a polymeric matrix

    Czech Academy of Sciences Publication Activity Database

    Nádherná, M.; Opekar, F.; Reiter, Jakub; Stulík, K.

    2012-01-01

    Roč. 161, č. 1 (2012), s. 811-817 ISSN 0925-4005 R&D Projects: GA MŠk LC523; GA AV ČR KJB200320901 Institutional research plan: CEZ:AV0Z40320502 Keywords : Amperometry * Gas sensor * Solid-state sensor * Planar sensor * Ionic liquid * Solid polymer electrolyte * Gold minigrid electrode * Nitrogen dioxide Subject RIV: CG - Electrochemistry Impact factor: 3.535, year: 2012

  3. Liquid Phase Plasma Synthesis of Iron Oxide Nanoparticles on Nitrogen-Doped Activated Carbon Resulting in Nanocomposite for Supercapacitor Applications.

    Science.gov (United States)

    Lee, Heon; Lee, Won-June; Park, Young-Kwon; Ki, Seo Jin; Kim, Byung-Joo; Jung, Sang-Chul

    2018-03-25

    Iron oxide nanoparticles supported on nitrogen-doped activated carbon powder were synthesized using an innovative plasma-in-liquid method, called the liquid phase plasma (LPP) method. Nitrogen-doped carbon (NC) was prepared by a primary LPP reaction using an ammonium chloride reactant solution, and an iron oxide/NC composite (IONCC) was prepared by a secondary LPP reaction using an iron chloride reactant solution. The nitrogen component at 3.77 at. % formed uniformly over the activated carbon (AC) surface after a 1 h LPP reaction. Iron oxide nanoparticles, 40~100 nm in size, were impregnated homogeneously over the NC surface after the LPP reaction, and were identified as Fe₃O₄ by X-ray photoelectron spectroscopy and X-ray diffraction. NC and IONCCs exhibited pseudo-capacitive characteristics, and their specific capacitance and cycling stability were superior to those of bare AC. The nitrogen content on the NC surface increased the compatibility and charge transfer rate, and the composites containing iron oxide exhibited a lower equivalent series resistance.

  4. Feasibility analysis of gas turbine inlet air cooling by means of liquid nitrogen evaporation for IGCC power augmentation

    International Nuclear Information System (INIS)

    Morini, Mirko; Pinelli, Michele; Spina, Pier Ruggero; Vaccari, Anna; Venturini, Mauro

    2015-01-01

    Integrated Gasification Combined Cycles (IGCC) are energy systems mainly composed of a gasifier and a combined cycle power plant. Since the gasification process usually requires oxygen as the oxidant, an Air Separation Unit (ASU) is also part of the plant. In this paper, a system for power augmentation in IGCC is evaluated. The system is based on gas turbine inlet air cooling by means of liquid nitrogen spray. In fact, nitrogen is a product of the ASU, but is not always exploited. In the proposed plant, the nitrogen is first liquefied to be used for inlet air cooling or stored for later use. This system is not characterized by the limits of water evaporative cooling systems (the lower temperature is limited by air saturation) and refrigeration cooling (the effectiveness is limited by the pressure drop in the heat exchanger). A thermodynamic model of the system is built by using a commercial code for energy conversion system simulation. A sensitivity analysis on the main parameters is presented. Finally the model is used to study the capabilities of the system by imposing the real temperature profiles of different sites for a whole year and by comparing to traditional inlet air cooling strategies. - Highlights: • Gas turbine inlet air cooling by means of liquid nitrogen spray. • Humidity condensation may form a fog which provides further power augmentation. • High peak and off peak electric energy price ratios make the system profitable

  5. Transport critical current measurement apparatus using liquid nitrogen cooled high-T(c) superconducting magnet with variable temperature insert.

    Science.gov (United States)

    Nishijima, G; Kitaguchi, H; Tshuchiya, Y; Nishimura, T; Kato, T

    2013-01-01

    We have developed an apparatus to investigate transport critical current (I(c)) as a function of magnetic field and temperature using only liquid nitrogen. The apparatus consists of a (Bi,Pb)(2)Sr(2)Ca(2)Cu(3)O(10) (Bi-2223) superconducting magnet, an outer dewar, and a variable temperature insert (VTI). The magnet, which is operated in depressurized liquid nitrogen, generates magnetic field up to 1.26 T. The sample is also immersed in liquid nitrogen. The pressure in the VTI is controlled from 0.02 to 0.3 MPa, which corresponds to temperature ranging from 66 to 88 K. We have confirmed the long-term stable operation of the Bi-2223 magnet at 1 T. The temperature stability of the sample at high transport current was also demonstrated. The apparatus provides easy-operating I(c) measurement environment for a high-T(c) superconductor up to 500 A in magnetic fields up to 1 T and in temperatures ranging from 66 to 88 K.

  6. Facile fabrication of palladium-ionic liquids-nitrogen-doped graphene nanocomposites as enhanced electro-catalyst for ethanol oxidation

    Science.gov (United States)

    Li, Shuwen; Yang, Honglei; Ren, Ren; Ma, Jianxin; Jin, Jun; Ma, Jiantai

    2015-10-01

    The palladium-ionic liquids-nitrogen-doped graphene nanocomposites are facile fabricated as enhanced electro-catalyst for ethanol oxidation. First, the ionic liquids functionalized nitrogen-doping graphene nanosheets (PDIL-NGS) with few layers is synthesized through a facile and effective one-pot hydrothermal method with graphene oxide as raw material, urea as reducing-doping agents and ionic liquids (ILs) derived from 3,4,9,10-perylene tetracarboxylic acid as functional molecules. The results of systematic characterization reveal that the PDIL molecules not only can functionalize NGS by π-π stacking with no affecting the nitrogen doping but also prevent the agglomeration of NGS. More importantly, the processing performance and the property of electron transfer are remarkably enhanced duo to introducing a large number of ILs groups. Then, the enhanced electrocatalytic Pd nanoparticles are successfully anchored on PDIL-NGS by a facile and surfactant-free synthetic technique. As an anode catalyst, the novel catalyst exhibits better kinetics, more superior electrocatalytic performance, higher tolerance and electrochemical stability than the other catalysts toward ethanol electrooxidation, owing to the role of PDIL molecules. Therefore, the new catalyst is believed to have the potential use for direct alcohol fuel cells in the future and the functionalized NGS is promising useful materials applied in other fields.

  7. Histomorphometric assessment of bone necrosis produced by two cryosurgery protocols using liquid nitrogen: an experimental study on rat femurs.

    Science.gov (United States)

    Costa, Fábio Wildson Gurgel; Brito, Gerly Anne de Castro; Pessoa, Rosana Maria Andrade; Studart-Soares, Eduardo Costa

    2011-01-01

    The aim of this study was to evaluate the effects of liquid nitrogen cryosurgery on the femoral diaphysis of rats. The femoral diaphyses of 42 Wistar rats were exposed to three local and sequential applications of liquid nitrogen for 1 or 2 min, intercalated with periods of 5 min of passive thawing. The animals were sacrificed after 1, 2, 4 and 12 weeks and the specimens obtained were processed and analyzed histomorphometrically. The depth and extent of peak bone necrosis were 124.509 µm and 2087.094 µm for the 1-min protocol, respectively, and 436.424 µm and 12046.426 µm for the 2-min protocol. Peak necrosis was observed in the second experimental week with both cryotherapy protocols. The present results indicate that the 2-min protocol produced more marked bone necrosis than the 1-min protocol. Although our results cannot be entirely extrapolated to clinical practice, they contribute to the understanding of the behavior of bone tissue submitted to different cycles of liquid nitrogen freezing and may serve as a basis for new studies.

  8. The potential of Mythimna sequax Franclemont eggs for the production of Trichogramma spp. after cryopreservation in liquid nitrogen

    Directory of Open Access Journals (Sweden)

    Magda Fernanda Paixão

    Full Text Available ABSTRACT The cryopreservation of noctuid eggs in liquid nitrogen has proved be a promising tool in the mass production of Trichogramma, however studies into this technique have only just begun. This study evaluated the response of different densities of the female of Trichogramma pretiosum Riley to the parasitism of Mythimna sequax eggs stored and not stored in liquid nitrogen, and the performance of females reared only in cryopreserved eggs. The study evaluated the influence of the number of T. pretiosum females (4, 8 and 12 released to parasitise 40 M. sequax eggs, stored and not stored for 15 days in liquid nitrogen, as well as the performance of T. pretiosum females reared in eggs stored for three generations and females reared in non-stored eggs. Parasitism by T. pretiosum in stored eggs was 84%, twice the value obtained in previous studies. The emergence of parasitoids was greater than 95% in both experiments. The performance of females raised in stored eggs did not differ from that of females raised in non-stored eggs. The data show that the technique of cryopreservation of M. sequax eggs may be a viable alternative in the mass production of T. pretiosum.

  9. Clinical results of primary malignant musculoskeletal tumor treated by wide resection and recycling autograft reconstruction using liquid nitrogen.

    Science.gov (United States)

    Paholpak, Permsak; Sirichativapee, Winai; Wisanuyotin, Taweechok; Kosuwon, Weerachai; Jeeravipoolvarn, Polasak

    2015-06-01

    To evaluate the clinical results of primary malignant musculoskeletal tumors treated with wide resection and recycling autograft reconstruction using liquid nitrogen. We reviewed 12 patients who had a primary malignant bone and soft tissue tumor treated by wide resection and recycling autograft reconstruction using liquid nitrogen between March 2006 and March 2013. The results were judged by recurrence, functional status and complications. Functional status was assessed according to the Musculoskeletal Tumor Society Score (MSTSS). Clinical failure was defined as need for reoperation in order to change the type of reconstruction or to amputate, and the presence of local recurrence. The most common tumor was osteosarcoma (eight cases) followed by Ewing's sarcoma (two cases). The tibia was the most frequently involved skeletal site (six cases) followed by the femur (three cases). The median follow-up period was 32 months. In 12 patients, 7 were still alive without recurrence. There were 3 clinical failures: 1 local recurrence and 2 graft complications at 28, 51 and 20 months after reconstruction, respectively. The main complication was infection (three cases). All osteotomy sites were radiographic unions, and the union time was 8.2 ± 2.7 months. The mean ± SD MSTSS score was 79% ± 11%; excellent functional results were achieved in seven patients. Recycling autograft reconstruction using liquid nitrogen had favorable clinical outcomes in terms of functional status and local recurrence. This reconstruction method, therefore, represents a reasonable alternative for limb salvage surgery. © 2014 Wiley Publishing Asia Pty Ltd.

  10. The influence of cavitation on the flow characteristics of liquid nitrogen through spray nozzles: A CFD study

    Science.gov (United States)

    Xue, Rong; Ruan, Yixiao; Liu, Xiufang; Cao, Feng; Hou, Yu

    2017-09-01

    Spray cooling with cryogen could achieve lower temperature level than refrigerant spray. The internal flow conditions within spray nozzles have crucial impacts on the mass flow rate, particle size, spray angle and spray penetration, thereby influencing the cooling performance. In this paper, CFD simulations based on mixture model are performed to study the cavitating flow of liquid nitrogen in spray nozzles. The cavitation model is verified using the experimental results of liquid nitrogen flow over hydrofoil. The numerical models of spray nozzle are validated against the experimental data of the mass flow rate of liquid nitrogen flow through different types of nozzles including the pressure swirl nozzle and the simple convergent nozzle. The numerical studies are performed under a wide range of pressure difference and inflow temperature, and the vapor volume fraction distribution, outlet vapor quality, mass flow rate and discharge coefficient are obtained. The results show that the outlet diameter, the pressure difference, and the inflow temperature significantly influence the mass flow rate of spray nozzles. The increase of the inflow temperature leads to higher saturation pressure, higher cavitation intensity, and more vapor at nozzle outlet, which can significantly reduce mass flow rate. While the discharge coefficient is mainly determined by the inflow temperature and has little dependence on the pressure difference and outlet diameter. Based on the numerical results, correlations of discharge coefficient are proposed for pressure swirl nozzle and simple convergent nozzles, respectively, and the deviation is less than 20% for 93% of data.

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

    International Nuclear Information System (INIS)

    Boyd, Ronald D.

    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 high velocity helium and liquid metal cooling have been considered as serious contenders. Each technique has its advantages and disadvantages [1], which must be weighed as to reliability and reduced cost of fusion reactor components. Previous studies [2] have set the stage for the present work, which will concentrate on fundamental thermal hydraulic issues associated with the h-international Thermonuclear Experimental Reactor (ITER) and the Engineering Design Activity (EDA). This proposed work is intended to increase our understanding of high heat flux removal alternatives as well as our present capabilities by: (1) including single-side heating effects in models for local predictions of heat transfer and critical heat flux; (2) inspection of the US, Japanese, and other possible data sources for single-side heating, with the aim of exploring possible correlations for both CHF and local heat transfer; and (3) assessing the viability of various high heat flux removal techniques. The latter task includes: (a) sub-cooled water flow boiling with enhancements such as twisted tapes, and hypervapotrons, (b) high velocity helium cooling, and (c) other potential techniques such as liquid metal cooling. This assessment will increase our understanding of: (1) hypervapotron heat transfer via fins, flow recirculation, and flow oscillation, and (2) swirl flow. This progress report contains selective examples of ongoing work. Section II contains an extended abstract, which is part of and evolving technical paper on single-side f heating. Section III describes additional details

  12. Electrical conductivity and equation of state of liquid nitrogen, oxygen, benzene, and 1-butene shocked to 60 GPa

    International Nuclear Information System (INIS)

    Hamilton, D.C.

    1986-01-01

    Measurements are reported for the electrical conductivity of liquid nitrogen (N 2 ), oxygen (O 2 ) and benzene (C 6 H 6 ), and Hugoniot equation of state of liquid 1-butene (C 4 H 8 ) under shock compressed conditions. The conductivity data span 7 x 10 -4 to 7 x 10 1 Ω -1 cm -1 over a dynamic pressure range 18.1 to 61.5 GPa and are discussed in terms of amorphous semiconduction models which include such transport phenomena as hopping, percolation, pseudogaps, and metallization. Excellent agreement is found between the equation-of-state measurements, which span a dynamic pressure range 12.3 to 53.8 GPa, and Ree's calculated values which assume a 2-phase mixture consisting of molecular hydrogen and carbon in a dense diamond-like phase. There is a 2-1/2 fold increase in the thermal pressure contribution over a less dense, stoichiometrically equivalent liquid. 90 refs., 48 figs., 8 tabs

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

    International Nuclear Information System (INIS)

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

    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 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

  14. Surface wettability and subcooling on nucleate pool boiling heat transfer

    Science.gov (United States)

    Suroto, Bambang Joko; Kohno, Masamichi; Takata, Yasuyuki

    2018-02-01

    The effect of varying surface wettabilities and subcooling on nucleate pool boiling heat transfer at intermediate heat flux has been examined and investigated. The experiments were performed using pure water as the working fluid and subcooling ranging from 0, 5 and 10 K, respectively. The three types of heat transfer block were used that are bare surface/hydrophilic (polished copper), superhydrophilic/TiO2-coated on copper and hydrophobic/PTFE surface. The experimental results will be examined by the existing model. The results show that the heat transfer performance of surfaces with PTFE coating is better at low heat flux. While for an intermediate heat flux, superhydrophilic surface (TiO2) is superior compared to hydrophilic and hydrophobic surfaces. It is observed that the heat transfer performance is decreasing when the sub cooling degree is increased.

  15. Effect of degree of subcooling on vapor explosion

    International Nuclear Information System (INIS)

    Xu Zhihong; Yang Yanhua; Li Tianshu

    2010-01-01

    In order to investigate the mechanism of the vapor explosion, an observable experiment equipment for low-temperature molten materials to be dropped into water was designed. In the experiment, molten material jet was injected into water to experimentally obtain the visualized information. This experiment results show that the degree of subcooling restrains the explosion. In order to validate the result by other aspects, the breakup experiment was conducted. Results show that the degree of water subcooling is important to melt breakup. High temperature of water is easy to increase the vapor generation during molten material falling, which decrease the drag and accelerated the molten material falling. At the same time, more vapor appear around the molten metal decrease the heat transfer amount between water and molten materials. The two experimental results coincide. (authors)

  16. Mechanisms and predictions for subcooled flow boiling CHF

    International Nuclear Information System (INIS)

    Liu, Wei; Nariai, Hideki; Inasaka, Fujio

    2000-01-01

    Corresponding to the two kinds of flow pattern reported in literature for subcooled flow boiling, two kinds of CHF triggering mechanism are considered existing with working in different working scope. On the base of a criterion proposed recently by the present authors, subcooled flow boiling data firstly are categorized into two groups by judging whether the first kind or the second kind of flow pattern is established. Possible CHF triggering mechanisms and prediction methods for the two kinds of flow pattern condition are discussed. By considering both the flow pattern development and CHF triggering mechanism, a detailed data categorization is carried out. The corresponding CHF occurrence properties in different data groups are summarized. Parametric trends are reviewed for the first and second kind of data group working condition respectively. Mass flux, pressure, inlet subcooling and inner diameter show almost same effects in the two different working conditions, while the ratio of heated length to diameter's effects on CHF show to be different. Research for the L/D effect on the CHF transverse the interface of the different data groups is carried out. (author)

  17. Automatic filling of liquid nitrogen traps auxiliary safety devices of a pumping unit; Alimentation automatique des pieges a azote liquide securites annexes d'un groupe de pompage

    Energy Technology Data Exchange (ETDEWEB)

    Chatel, S [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1969-07-01

    The liquid nitrogen traps in our laboratories are generally filled at fixed time intervals, the supply being cut when the liquid flowing through the overflow pipe acts on a lever to which is fixed a small cup fitted with a hole which allows the water of condensation to escape. This system is reliable. After a certain time however, the escape hole blocks up, water accumulates and the lever arm no longer works properly. Furthermore the duration of any cuts in the current, is added to the fixed time intervals, and in this case there can be a lack of liquid nitrogen for several hours after the current has been restored. The device described here avoids these problems. A stainless steel tube containing a copper wire passes into the trap and is immersed in the nitrogen which boils at its tip. A mercury manometer with concentric reservoirs, or an oil manometer, acting on two micro switches through a floater, records the pressure corresponding to the difference in level and controls the filling operation. If there is a lack of nitrogen, a valve can be closed by means of a falling weight, or a diffusion pump can be cut off; one time switch and at least two relays are required. One single relay can be used to control, the supply of several similar traps placed in series. [French] Dans nos laboratoires, les pieges a azote liquide sont generalement remplis a intervalles fixes jusqu'a ce que le trop-plein d'azote actionne une bascule dont le recipient presente un petit trou par ou s'en va l'eau de condensation. Ce systeme est sur. A la longue, pourtant, le trou d'ecoulement se bouche, l'eau s'accumule et la bascule cesse de fonctionner. De plus, la duree des pannes de courant s'ajoute aux 'intervalles fixes' de sorte que l'azote peut manquer plusieurs heures apres le retour du courant. Le dispositif suivant evite ces ennuis. Un tube d'acier inoxydable contenant un fil de cuivre penetre dans le piege et plonge dans l'azote qui bout a son extremite. Un manometre a mercure a cuves

  18. Liquid methane gelled with methanol and water reduces rate of nitrogen absorption

    Science.gov (United States)

    Vanderwall, E. M.

    1972-01-01

    Dilution of gelant vapor with inert carrier gas accomplishes gelation. Mixture is injected through heated tube and orifice into liquid methane for immediate condensation within bulk of liquid. Direct dispersion of particles in liquid avoids condensation on walls of vessel and eliminates additional mixing.

  19. The Application of Liquid Nitrogen Spray Cryotherapy in Treatment of Bronchial Stenosis.

    Science.gov (United States)

    Janke, Kelly J; Abbas, Abbas El-Sayed; Ambur, Vishnu; Yu, Daohai

    Spray cryotherapy (SCT), the application of liquid nitrogen in a noncontact form, has been demonstrated to have efficacy in treating various types of pathologic lesions of the airway when used as an adjunct with bronchoscopy. The purpose of the study was to evaluate the results of the use of bronchoscopic SCT on the airway in a single institution. We performed a retrospective review of data collected on all patients who underwent SCT to re-establish or improve airway patency in an 11-month period. Patients were classified based on the nature of their disease into benign or malignant. Demographic data, change in luminal patency, and clinical outcomes were recorded. The percent of stenosis was divided into grades according to the following classification: 1, ≤25%; 2, 26% to 50%; 3, 51% to 75%; and 4, ≥76%. We defined successful completion of treatment as obtaining a final patency of grade 1. Twenty-two patients met inclusion criteria, with 45.5% (10 patients) having benign stenosis and 54.5% (12 patients) malignant. At initial bronchoscopic evaluation, the median grade of stenosis was 4 for malignant disease and 3.5 for benign disease. The median final posttreatment grade of stenosis was 2 for malignant disease and 1 for benign. The median improvement in grade of stenosis after treatment was 2 for both malignant and benign causes (Wilcoxon test, P = 0.92). Final patency of grade 1 was achieved in 42% of malignant stenosis and 80% of benign. Overall, 86.4% of patients had an improvement in grade of stenosis after treatment. The rate of morbidity was 4.5% (1/22) of all patients. The median change in grade after treatment was 2 grades of improvement for both the benign and malignant groups. These results provide evidence that the use of SCT is equally efficacious for both types of stenosis with an expectation of overall improvement in luminal patency, offering a safe and effective method of achieving airway patency in a minimally invasive fashion. This study

  20. Physicochemical processes in embryonic plant tissue during the transition to the state of cold anabiosis and storage at liquid nitrogen temperature

    Science.gov (United States)

    Khodko, A. T.; Lysak, Yu. S.

    2017-10-01

    Critical opalescence phenomenon was observed in the cytoplasm of garlic embryonic tissue—meristem—upon cooling in liquid nitrogen vapor, indicating liquid-liquid phase transition in the system. It was established that cells of the meristem tissue survive the cooling-thawing cycle. We suggest that the transition of meristem tissue to the state of anabiosis is mainly due to a drastic slowing of the diffusion in the cytoplasm caused by the passage of the solution through the critical point, followed by the formation of a dispersed system—a highly concentrated emulsion—as a result of a liquid-liquid phase transition. This macrophase separation is characteristic of polymer-solvent systems. We established the regime of cooling down to liquid nitrogen temperature and subsequent thawing in the cryopreservation cycle for the biological object under study, which ensures the preservation of tissue viability.

  1. First 10 kg of naked germanium detectors installed in liquid nitrogen in GENIUS Test-Facility in GRAN-SASSO

    Energy Technology Data Exchange (ETDEWEB)

    Klapdor-Kleingrothaus, H.V. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany)

    2004-07-01

    The GENIUS Test Facility has come into operation in Gran Sasso on May 5, 2003 with its first ten kg of naked Ge detectors in liquid nitrogen. This is the first time that this novel technique for extreme background reduction in search for rare decays is applied under the background conditions of an underground laboratory. GENIUS-TF has the potential to check the DAMA evidence for cold dark matter by modulation, and possibly, to improve the accuracy of the recently observed first signal for neutrinoless double beta decay. (orig.)

  2. First 10 kg of naked germanium detectors installed in liquid nitrogen in GENIUS Test-Facility in GRAN-SASSO

    International Nuclear Information System (INIS)

    Klapdor-Kleingrothaus, H.V.

    2004-01-01

    The GENIUS Test Facility has come into operation in Gran Sasso on May 5, 2003 with its first ten kg of naked Ge detectors in liquid nitrogen. This is the first time that this novel technique for extreme background reduction in search for rare decays is applied under the background conditions of an underground laboratory. GENIUS-TF has the potential to check the DAMA evidence for cold dark matter by modulation, and possibly, to improve the accuracy of the recently observed first signal for neutrinoless double beta decay. (orig.)

  3. A Simple Method to Measure the Thermal contraction Percentage of a Solid Between Room and Liquid Nitrogen Temperatures

    International Nuclear Information System (INIS)

    Grau Carles, A.; Grau Malonda, A.

    2000-01-01

    We described how to build a simple device for measuring, with a reasonable good accuracy, the thermal contraction of a flat sample between room and liquid nitrogen temperatures. The contraction percentage of the sample is determined by the dimensional comparison of two images taken through the bottom of a transparent quartz tray. Instead of a photo or video camera, a high-resolution flatbed scanner is utilized to avoid the correction of perspectives. The so-called Grueneisen approximation are applied to evaluate the contraction percentages for intermediate temperatures. (Author) 28 refs

  4. Lap shear strength of selected adhesives (epoxy, varnish, B-stage glass cloth) in liquid nitrogen and at room temperature

    International Nuclear Information System (INIS)

    Froelich, K.J.; Fitzpatrick, C.M.

    1976-12-01

    The adhesives included several epoxy resins, a varnish, and a B-stage glass cloth (a partially cured resin in a fiberglass cloth matrix). Several parameters critical to bond strength were varied: adhesive and adherend differences, surface preparation, coupling agents, glass cloth, epoxy thickness, fillers, and bonding pressure and temperature. The highest lap shear strengths were obtained with the B-shear glass cloth at both liquid nitrogen and room temperatures with values of approximately 20 MPa (3000 psi) and approximately 25.5 MPa (3700 psi) respectively

  5. Photo- and electro-luminescence of rare earth doped ZnO electroluminors at liquid nitrogen temperature

    International Nuclear Information System (INIS)

    Bhushan, S.; Kaza, B.R.; Pandey, A.N.

    1981-01-01

    Photo (PL) and electroluminescent (EL) spectra of some rare earth (La, Gd, Er or Dy) doped ZnO electroluminors have been investigated at liquid nitrogen temperature (LNT) and compared with their corresponding results at room temperature (RT). In addition to three bands observed at RT, one more band on the higher wavelength side appears in EL spectra. Spectral shift with the exciting intensity at LNT supports the donor-acceptor (DA) model in which the rare earths form the donor levels. From the temperature dependent studies of PL and EL brightness, the EL phenomenon is found to be more susceptible to traps. (author)

  6. Development and validation of a new solver based on the interfacial area transport equation for the numerical simulation of sub-cooled boiling with OpenFOAM CFD code for nuclear safety applications

    Energy Technology Data Exchange (ETDEWEB)

    Alali, Abdullah

    2014-02-21

    The one-group interfacial area transport equation has been coupled to a wall heat flux partitioning model in the framework of two-phase Eulerian approach using the OpenFOAM CFD code for better prediction of subcooled boiling phenomena which is essential for safety analysis of nuclear reactors. The interfacial area transport equation has been modified to include the effect of bubble nucleation at the wall and condensation by subcooled liquid in the bulk that governs the non-uniform bubble size distribution.

  7. Development and validation of a new solver based on the interfacial area transport equation for the numerical simulation of sub-cooled boiling with OpenFOAM CFD code for nuclear safety applications

    International Nuclear Information System (INIS)

    Alali, Abdullah

    2014-01-01

    The one-group interfacial area transport equation has been coupled to a wall heat flux partitioning model in the framework of two-phase Eulerian approach using the OpenFOAM CFD code for better prediction of subcooled boiling phenomena which is essential for safety analysis of nuclear reactors. The interfacial area transport equation has been modified to include the effect of bubble nucleation at the wall and condensation by subcooled liquid in the bulk that governs the non-uniform bubble size distribution.

  8. Quantitative study of sniffer leak rate and pressure drop leak rate of liquid nitrogen panels of SST-1 tokamak

    Science.gov (United States)

    Pathan, F. S.; Khan, Z.; Semwal, P.; Raval, D. C.; Joshi, K. S.; Thankey, P. L.; Dhanani, K. R.

    2008-05-01

    Steady State Super-conducting (SST-1) Tokamak is in commissioning stage at Institute for Plasma Research. Vacuum chamber of SST-1 Tokamak consists of 1) Vacuum vessel, an ultra high vacuum (UHV) chamber, 2) Cryostat, a high vacuum (HV) chamber. Cryostat encloses the liquid helium cooled super-conducting magnets (TF and PF), which require the thermal radiation protection against room temperature. Liquid nitrogen (LN2) cooled panels are used to provide thermal shield around super-conducting magnets. During operation, LN2 panels will be under pressurized condition and its surrounding (cryostat) will be at high vacuum. Hence, LN2 panels must have very low leak rate. This paper describes an experiment to study the behaviour of the leaks in LN2 panels during sniffer test and pressure drop test using helium gas.

  9. Quantitative study of sniffer leak rate and pressure drop leak rate of liquid nitrogen panels of SST-1 tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Pathan, F S; Khan, Z; Semwal, P; Raval, D C; Joshi, K S; Thankey, P L; Dhanani, K R [Institute for Plasma Research, Bhat, Gandhinagar - 382 428, Gujarat (India)], E-mail: firose@ipr.res.in

    2008-05-01

    Steady State Super-conducting (SST-1) Tokamak is in commissioning stage at Institute for Plasma Research. Vacuum chamber of SST-1 Tokamak consists of 1) Vacuum vessel, an ultra high vacuum (UHV) chamber, 2) Cryostat, a high vacuum (HV) chamber. Cryostat encloses the liquid helium cooled super-conducting magnets (TF and PF), which require the thermal radiation protection against room temperature. Liquid nitrogen (LN2) cooled panels are used to provide thermal shield around super-conducting magnets. During operation, LN{sub 2} panels will be under pressurized condition and its surrounding (cryostat) will be at high vacuum. Hence, LN{sub 2} panels must have very low leak rate. This paper describes an experiment to study the behaviour of the leaks in LN{sub 2} panels during sniffer test and pressure drop test using helium gas.

  10. Quantitative study of sniffer leak rate and pressure drop leak rate of liquid nitrogen panels of SST-1 tokamak

    International Nuclear Information System (INIS)

    Pathan, F S; Khan, Z; Semwal, P; Raval, D C; Joshi, K S; Thankey, P L; Dhanani, K R

    2008-01-01

    Steady State Super-conducting (SST-1) Tokamak is in commissioning stage at Institute for Plasma Research. Vacuum chamber of SST-1 Tokamak consists of 1) Vacuum vessel, an ultra high vacuum (UHV) chamber, 2) Cryostat, a high vacuum (HV) chamber. Cryostat encloses the liquid helium cooled super-conducting magnets (TF and PF), which require the thermal radiation protection against room temperature. Liquid nitrogen (LN2) cooled panels are used to provide thermal shield around super-conducting magnets. During operation, LN 2 panels will be under pressurized condition and its surrounding (cryostat) will be at high vacuum. Hence, LN 2 panels must have very low leak rate. This paper describes an experiment to study the behaviour of the leaks in LN 2 panels during sniffer test and pressure drop test using helium gas

  11. Experiments on the effects of nanoparticles on subcooled nucleate pool boiling

    Science.gov (United States)

    Kangude, Prasad; Bhatt, Dhairya; Srivastava, Atul

    2018-05-01

    The effect of nanoparticles on a single bubble-based nucleate pool boiling phenomenon under subcooled conditions has been studied. Water (as the base fluid) and two different concentrations of water-silica nanofluids (0.005% and 0.01% V/V) have been employed as the working fluids. The boiling experiments have been conducted in a specially designed chamber, wherein an ITO-coated heater substrate has been used to induce single bubble nucleation. Measurements have been performed in a completely non-intrusive manner using one of the refractive index-based diagnostics techniques, namely, rainbow schlieren deflectometry. Thus, the thermal gradients prevailing in the boiling chamber have directly been mapped as a two-dimensional distribution of hue values that are recorded in the form of rainbow schlieren images. The schlieren-based measurements clearly revealed the plausible influence of nanoparticles on the strength of temperature gradients prevailing in the boiling chamber. As compared to the base fluid, the experiments with dilute nanofluids showed that the suspended nanoparticles tend to diffuse (homogenize) the strength of temperature gradients, both in the vicinity of the heated substrate and in the thermal boundary layer enveloping the vapor bubble. An overall reduction in the bubble volume and dynamic contact angle was seen with increasing concentrations of dilute nanofluids. In addition, the vapor bubble was found to assume a more spherical shape at higher concentrations of dilute nanofluids in comparison to its shape with water-based experiments. Clear oscillations of the vapor bubble in the subcooled pool of liquids (water and/or nanofluids) were observed, the frequency of which was found to be significantly reduced as the nanoparticle concentration was increased from 0% (water) to 0.01% (V/V). A force balance analysis has been performed to elucidate the plausible mechanisms explaining the observed trends of the oscillation frequencies of the vapor bubble.

  12. Effect of cooling rate on the survival of cryopreserved rooster sperm: Comparison of different distances in the vapor above the surface of the liquid nitrogen.

    Science.gov (United States)

    Madeddu, M; Mosca, F; Abdel Sayed, A; Zaniboni, L; Mangiagalli, M G; Colombo, E; Cerolini, S

    2016-08-01

    The aim of the present trial was to study the effect of different freezing rates on the survival of cryopreserved rooster semen packaged in straws. Slow and fast freezing rates were obtained keeping straws at different distances in the vapor above the surface of the nitrogen during freezing. Adult Lohmann roosters (n=27) were used. Two experiments were conducted. In Experiment 1, semen was packaged in straws and frozen comparing the distances of 1, 3 and 5cm in nitrogen vapor above the surface of the liquid nitrogen. In Experiment 2, the distances of 3, 7 and 10cm above the surfaces of the liquid nitrogen were compared. Sperm viability, motility and progressive motility and the kinetic variables were assessed in fresh and cryopreserved semen samples. The recovery rates after freezing/thawing were also calculated. In Experiment 1, there were no significant differences among treatments for all semen quality variables. In Experiment 2, the percentage of viable (46%) and motile (22%) sperm in cryopreserved semen was greater when semen was placed 3cm compared with 7 and 10cm in the vapor above the surface of the liquid nitrogen. The recovery rate of progressive motile sperm after thawing was also greater when semen was stored 3cm in the vapor above the surface of the liquid nitrogen. More rapid freezing rates are required to improve the survival of rooster sperm after cryopreservation and a range of distances from 1 to 5cm in nitrogen vapor above the surface of the liquid nitrogen is recommended for optimal sperm viability. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Calculation of Void Volume Fraction in the Subcooled and Quality Boiling Regions

    Energy Technology Data Exchange (ETDEWEB)

    Rouhani, S Z; Axelsson, E

    1968-10-15

    The complex problem of void calculation in the different regions of flow boiling is divided in two parts. The first part includes only the description of the mechanisms and the calculation of the rates of heat transfer for vapour and liquid. It is assumed that heat is removed by vapour generation, heating of the liquid that replaces the detached bubbles, and in some parts, by single phase heat transfer. By considering the rate of vapour condensation in liquid, an equation for the differential changes in the true steam quality throughout the boiling regions is obtained. Integration of this equation yields the vapour weight fraction at any position. The second part of the problem concerns the determination of the void fractions corresponding to the calculated steam qualities. For this purpose we use the derivations of Zuber and Findlay. This model is compared with data from different geometries including small rectangular channels and large rod bundles. The data covered pressures from 19 to 138 bars, heat fluxes from 18 to 120 W/cm{sup 2} with many different subcoolings and mass velocities. The agreement is generally very good.

  14. Experimental study on two-phase flow parameters of subcooled boiling in inclined annulus

    International Nuclear Information System (INIS)

    Lee, Tae Ho; Kim, Moon Oh; Park, Goon Cherl

    1999-01-01

    Local two-phase flow parameters of subcooled flow boiling in inclined annulus were measured to investigate the effect of inclination on the internal flow structure. Two-conductivity probe technique was applied to measured local gas phasic parameters, including void by fraction, vapor bubble frequency, chord length, vapor bubble velocity and interfacial area concentration. Local liquid velocity was measured by Pitot tube. Experiments were conducted for three angles of inclination: 0 o (vertical), 30 o , 60 o . The system pressure was maintained at atmospheric pressure. The range of average void fraction was up to 10 percent and the average liquid superficial velocities were less than 1.3 m/sec. The results of experiments showed that the distributions of two-phase flow parameters were influenced by the angle of channel inclination. Especially, the void fraction and chord length distributions were strongly affected by the increase of inclination angle, and flow pattern transition to slug flow was observed depending on the flow conditions. The profiles of vapor velocity, liquid velocity and interfacial area concentration were found to be affected by the non-symmetric bubble size distribution in inclined channel. Using the measured distributions of local phasic parameters, an analysis for predicting average void fraction was performed based on the drift flux model and flowing volumetric concentration. And it was demonstrated that the average void fraction can be more appropriately presented in terms of flowing volumetric concentration. (Author). 18 refs., 2 tabs., 18 figs

  15. Calculation of Void Volume Fraction in the Subcooled and Quality Boiling Regions

    International Nuclear Information System (INIS)

    Rouhani, S.Z.; Axelsson, E.

    1968-10-01

    The complex problem of void calculation in the different regions of flow boiling is divided in two parts. The first part includes only the description of the mechanisms and the calculation of the rates of heat transfer for vapour and liquid. It is assumed that heat is removed by vapour generation, heating of the liquid that replaces the detached bubbles, and in some parts, by single phase heat transfer. By considering the rate of vapour condensation in liquid, an equation for the differential changes in the true steam quality throughout the boiling regions is obtained. Integration of this equation yields the vapour weight fraction at any position. The second part of the problem concerns the determination of the void fractions corresponding to the calculated steam qualities. For this purpose we use the derivations of Zuber and Findlay. This model is compared with data from different geometries including small rectangular channels and large rod bundles. The data covered pressures from 19 to 138 bars, heat fluxes from 18 to 120 W/cm 2 with many different subcoolings and mass velocities. The agreement is generally very good

  16. Comparison of heat transfer in liquid and slush nitrogen by numerical simulation of cooling rates for French straws used for sperm cryopreservation.

    Science.gov (United States)

    Sansinena, M; Santos, M V; Zaritzky, N; Chirife, J

    2012-05-01

    Slush nitrogen (SN(2)) is a mixture of solid nitrogen and liquid nitrogen, with an average temperature of -207 °C. To investigate whether plunging a French plastic straw (commonly used for sperm cryopreservation) in SN(2) substantially increases cooling rates with respect to liquid nitrogen (LN(2)), a numerical simulation of the heat conduction equation with convective boundary condition was used to predict cooling rates. Calculations performed using heat transfer coefficients in the range of film boiling confirmed the main benefit of plunging a straw in slush over LN(2) did not arise from their temperature difference (-207 vs. -196 °C), but rather from an increase in the external heat transfer coefficient. Numerical simulations using high heat transfer (h) coefficients (assumed to prevail in SN(2)) suggested that plunging in SN(2) would increase cooling rates of French straw. This increase of cooling rates was attributed to a less or null film boiling responsible for low heat transfer coefficients in liquid nitrogen when the straw is placed in the solid-liquid mixture or slush. In addition, predicted cooling rates of French straws in SN(2) tended to level-off for high h values, suggesting heat transfer was dictated by heat conduction within the liquid filled plastic straw. Copyright © 2012 Elsevier Inc. All rights reserved.

  17. Mechanistic modeling of CHF in forced-convection subcooled boiling

    International Nuclear Information System (INIS)

    Podowski, M.Z.; Alajbegovic, A.; Kurul, N.; Drew, D.A.; Lahey, R.T. Jr.

    1997-05-01

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

  18. Use of ultrasonic waves in sub-cooled boiling

    International Nuclear Information System (INIS)

    Bartoli, Carlo; Baffigi, Federica

    2012-01-01

    This work focuses on the use of ultrasounds in heat transfer fields. Under particular conditions, ultrasonic waves induce a convection coefficient increase. This initial research work, indicates that there are some practical applications in the cooling of the latest generation electronic components. In the first part of this paper, some background on this subject is reported. The ultrasound's influence on heat transfer rate has been observed since the 60's: different authors studied the cooling effect due to ultrasonic waves from different heat transfer regimes. The most investigated configuration was a thin platinum wire immersed in water. Later, a bibliographic research on possible practical applications of ultrasounds was carried out. This research focused in particular on the issue for 3D highly integrated electronic components. For these systems the thermal problem is a major challenge, because they cannot exceed critical temperatures, after which they could be damaged irreversibly. On the basis of our experimental results, ultrasounds could represent a valid means to overcome these thermal problems. Finally, the paper presents a series of experiments performed in the Thermal-Fluid- Dynamic Lab at the Energy and Engineering Systems Department of University of Pisa. The experiments provide systematic evidence of ultrasonic waves effects, on free convection heat transfer, from a heated circular cylinder to sub-cooled water, at atmospheric pressure. Many variables involved in the heat transfer rise were tested, for example: the ultrasonic generator's power, the position of the heater inside the ultrasonic tank, the variation of the water sub-cooling degree, as function of the heat flux needed dissipating. The aim of the experiment was to find out the set of optimal conditions, in order to successively apply all the results to real packaging systems, as mentioned before. The maximum increase in the heat transfer coefficient, due to ultrasonic waves, was 57

  19. Reynolds analogy for subcooled surface boiling under forced convection

    International Nuclear Information System (INIS)

    Avdeev, A.A.

    1982-01-01

    For the case of subcooled surface boiling under forced convection the analytic expression of analogy between the heat transfer and carry pulse (Reynolds analogy) is derived. It is concluded that the obtained dependence creates the basis for solution of a series of problems of surface boiling physics. On the basis of the performed analysis the method of coordinate calculation of the origin of intensive vapour generation is developed and the formula for calculation of the broken-off-bubble radius under forced convection is derived [ru

  20. Survival and death of seeds during liquid nitrogen storage: a case study on seeds with short lifespans.

    Science.gov (United States)

    Ballesteros, D; Pence, V C

    The low temperature of liquid nitrogen is assumed to stop ageing and preserve viability indefinitely, however there are few validating data sets. The use of seeds to test these assumptions is important because other cryopreserved systems lack quantitative measures of viability to allow comparisons among timed points. To evaluate survival of a collection of seeds with short lifespans stored 12-20 years in liquid nitrogen. Seeds from 11 species (26 accessions) were removed from cryostorage and evaluated for germination and normal growth. Germination of Plantago cordata and Betula spp. seeds did not decrease significantly during cryostorage. However, Populus deltoides and most Salix spp. accessions showed a significant decrease in germination, with further loss observed when P. deltoides seedlings were followed to the young plant stage. Seeds of initial low quality showed greater deterioration during cryostorage. Cryostorage maintained viability of Salix and Populus seeds longer than other temperatures. However, ageing was not completely stopped and seed longevity was shorter than that predicted for many other species. A high initial seed quality is important in order to obtain the maximum benefit of cryostorage.

  1. IMPACT OF LIQUID NITROGEN EXPOSURE ON SELECTED BIOCHEMICAL AND STRUCTURAL PARAMETERS OF HYDRATED Phaseolus vulgaris L. SEEDS.

    Science.gov (United States)

    Cejas, Inaudis; Rivas, Maribel; Nápoles, Lelurlys; Marrero, Pedro; Yabor, Lourdes; Aragón, Carlos; Pérez, Aurora; Engelmann, Florent; Martínez-Montero, Marcos Edel; Lorenzo, José Carlos

    2015-01-01

    It is well known that cryopreserving seeds with high water content is detrimental to survival, but biochemical and structural parameters of cryostored hydrated common bean seeds have not been published. The objective of this work was to study the effect of liquid nitrogen exposure on selected biochemical and structural parameters of hydrated Phaseolus vulgaris seeds. We cryopreserved seeds at various moisture contents and evaluated: germination; electrolyte leakage; fresh seed weight; levels of chlorophyll pigments, malondialdehyde, other aldehydes, phenolics and proteins; thickness of cotyledon epidermis, parenchyma, and starch storage parenchyma; and radicle and plumule lengths. Germination was totally inhibited when seeds were immersed in water for 50 min (moisture content of 38%, FW basis) before cryopreservation. The combined effects of seed water imbibition and cryostorage decreased phenolics (free, cell wall-linked, total), chlorophyll a and protein content. By contrast, electrolyte leakage and levels of chlorophyll b and other aldehydes increased as a result of the combination of these two experimental factors. These were the most significant effects observed during exposure of humid seed to liquid nitrogen. Further studies are still required to clarify the molecular events taking place in plant cells during cryostorage.

  2. Identification of multiply charged proteins and amino acid clusters by liquid nitrogen assisted spray ionization mass spectrometry.

    Science.gov (United States)

    Kumar Kailasa, Suresh; Hasan, Nazim; Wu, Hui-Fen

    2012-08-15

    The development of liquid nitrogen assisted spray ionization mass spectrometry (LNASI MS) for the analysis of multiply charged proteins (insulin, ubiquitin, cytochrome c, α-lactalbumin, myoglobin and BSA), peptides (glutathione, HW6, angiotensin-II and valinomycin) and amino acid (arginine) clusters is described. The charged droplets are formed by liquid nitrogen assisted sample spray through a stainless steel nebulizer and transported into mass analyzer for the identification of multiply charged protein ions. The effects of acids and modifier volumes for the efficient ionization of the above analytes in LNASI MS were carefully investigated. Multiply charged proteins and amino acid clusters were effectively identified by LNASI MS. The present approach can effectively detect the multiply charged states of cytochrome c at 400 nM. A comparison between LNASI and ESI, CSI, SSI and V-EASI methods on instrumental conditions, applied temperature and observed charge states for the multiply charged proteins, shows that the LNASI method produces the good quality spectra of amino acid clusters at ambient conditions without applied any electric field and heat. To date, we believe that the LNASI method is the most simple, low cost and provided an alternative paradigm for production of multiply charged ions by LNASI MS, just as ESI-like ions yet no need for applying any electrical field and it could be operated at low temperature for generation of highly charged protein/peptide ions. Copyright © 2012 Elsevier B.V. All rights reserved.

  3. DETERMINATION OF CONVECTIVE HEAT TRANSFER COEFFICIENT AT THE OUTER SURFACE OF A CRYOVIAL BEING PLUNGED INTO LIQUID NITROGEN.

    Science.gov (United States)

    Wang, T; Zhao, G; Tang, H Y; Jiang, Z D

    2015-01-01

    Cell survival upon cryopreservation is affected by the cooling rate. However, it is difficult to model the heat transfer process or to predict the cooling curve of a cryoprotective agent (CPA) solution due to the uncertainty of its convective heat transfer coefficient (h). To measure the h and to better understand the heat transfer process of cryovials filled with CPA solution being plunged in liquid nitrogen. The temperatures at three locations of the CPA solution in a cryovial were measured. Different h values were selected after the cooling process was modeled as natural convection heat transfer, the film boiling and the nucleate boiling, respectively. And the temperatures of the selected points are simulated based on the selected h values. h was determined when the simulated temperature best fitted the experimental temperature. When the experimental results were best fitted, according to natural convection heat transfer model, h(1) = 120 W/(m(2)·K) while due to film boiling and nucleate boiling regimes h(f) = 5 W/(m(2)·K) followed by h(n) = 245 W/(m(2)·K). These values were verified by the differential cooling rates at the three locations of a cryovial. The heat transfer process during cooling in liquid nitrogen is better modeled as film boiling followed by nucleate boiling.

  4. Low cyclic fatigue behavior of 32 % Mn nonmagnetic steel and the effects of C and N in liquid nitrogen and liquid helium

    International Nuclear Information System (INIS)

    Shibata, Koji; Fujita, Toshio

    1987-01-01

    The effects of testing temperature, C, and N on the low cyclic deformation behavior of 32 % Mn non-magnetic steels have been investigated in ambient air, liquid nitrogen, and liquid helium. It was observed that several problems exsisted in fatigue tests in liquid helium due to special phenomena occurred at very low temperatures. The steel containing 0.3 % N, which showed large fatigue softening at room temperature, increased the trend toward the softening at low temperatures. The steel containing 0.14 % C and 0.13 % N also increased the tendency of softening with the temperature decrease, while it was not so large at room temperature. Dislocation configuration in steels showing the softening tended to be mainly planne at very low temperatures same as at room temperature. The steel with a very low content of C and N, the 0.3 % C steel, and the 0.12 % N steel did not show the softening at low temperatures, but showed only fatigue hardening. The hardening of the former two steels increased remarkably as the temperature decreased. This phenomenon was attributable to ε martensite induced by the cyclic deformation. The fatigue softening behavior observed at low temperatures could qualitatively be explained with the hypothesis that the softening occurred through the breakdown of solid solution strengthening due to IS complexes during the cyclic deformation. (author)

  5. Controllable synthesis of nitrogen-doped hollow mesoporous carbon spheres using ionic liquids as template for supercapacitors

    Science.gov (United States)

    Chen, Aibing; Li, Yunqian; Liu, Lei; Yu, Yifeng; Xia, Kechan; Wang, Yuying; Li, Shuhui

    2017-01-01

    We have demonstrated a facile and controllable synthesis of monodispersed nitrogen-doped hollow mesoporous carbon spheres (N-HMCSs) using resorcinol/formaldehyde resin as a carbon precursor, tetraethyl orthosilicate as a structure-assistant agent, ionic liquids (ILs) as soft template, partial carbon sources, and nitrogen sources. The sizes and the architectures including hollow and yolk-shell of resultant carbon spheres can be efficiently controlled through the adjustment of the content of ILs. Alkyl chain length of the ILs also has an important effect on the formation of N-HMCSs. With proper alkyl chain length and content of ILs, the resultant N-HMCSs show monodispersed hollow spheres with high surface areas (up to 1158 m2 g-1), large pore volumes (up to 1.70 cm3 g-1), and uniform mesopore size (5.0 nm). Combining the hollow mesoporous structure, high porosity, large surface area, and nitrogen functionality, the as-synthesized N-HMCSs have good supercapacitor performance with good capacitance (up to 159 F g-1) and favorable capacitance retention (88% capacitive retention after 5000 cycles).

  6. Pyrolysis of high-ash sewage sludge in a circulating fluidized bed reactor for production of liquids rich in heterocyclic nitrogenated compounds.

    Science.gov (United States)

    Zuo, Wu; Jin, Baosheng; Huang, Yaji; Sun, Yu; Li, Rui; Jia, Jiqiang

    2013-01-01

    A circulating fluidized bed reactor was used for pyrolyzing sewage sludge with a high ash content to produce liquids rich in heterocyclic nitrogenated compounds. GC/MS and FTIR analyses showed that heterocyclic nitrogenated compounds and hydrocarbons made up 38.5-61.21% and 2.24-17.48% of the pyrolysis liquids, respectively. A fluidized gas velocity of 1.13 m/s, a sludge feed rate of 10.78 kg/h and a particle size of 1-2mm promoted heterocyclic nitrogenated compound production. Utilizing heterocyclic nitrogenated compounds as chemical feedstock could be a way for offsetting the cost of sewage sludge treatment. Copyright © 2012 Elsevier Ltd. All rights reserved.

  7. A case of death of the driver due to environmental asphyxia by liquid nitrogen leakage in the cabin of the car during a road accident

    Science.gov (United States)

    Raczkowska, Zuzanna; Samojłowicz, Dorota

    2013-01-01

    Nitrogen causes environmental asphyxia by displacing oxygen in the air leading to death. The study presents a case of a death of a driver death who was transporting flasks with liquid nitrogen that depressurized during an accident. The mechanism and cause of death were determined based on the result of the autopsy and histopathologic examination. The authors emphasize the relevance of accident scene inspection during establishing the cause of death in similar cases.

  8. Research on axial total pressure distributions of sonic steam jet in subcooled water

    International Nuclear Information System (INIS)

    Wu Xinzhuang; Li Wenjun; Yan Junjie

    2012-01-01

    The axial total pressure distributions of sonic steam jet in subcooled water were experimentally investigated for three different nozzle diameters (6.0 mm, 8.0 mm and 10.0 mm). The inlet steam pressure, and pool subcooling subcooled water temperature were in the range of 0.2-0.6 MPa and 420-860 ℃, respectively. The effect of steam pressure, subcooling water temperature and nozzle size on the axial pressure distributions were obtained, and also the characteristics of the maximum pressure and its position were studied. The results indicated that the characteristics of the maximum pressure were influenced by the nozzle size for low steam pressure, but the influence could be ignored for high steam pressure. Moreover, a correlation was given to correlate the position of the maximum pressure based on steam pressure and subcooling water temperature, and the discrepancies of predictions and experiments are within ±15%. (authors)

  9. An automatic device for refilling liquid nitrogen traps at constant time intervals; Dispositif automatique assurant le remplissage de pieces en azote liquide a intervales de temps constant

    Energy Technology Data Exchange (ETDEWEB)

    Bourguillot, R; Lohez, P [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    We have been led to study the design of an automatic device for the filling of liquid nitrogen traps at constant time intervals in connection with the maintenance of a type MS 5 mass spectrometer; in the tube of this apparatus it is necessary to maintain a vacuum of about 10{sup -7} mm of mercury. The replenishing is done every four hours. The presence in the vacuum section of an electron multiplier has led us to provide a safety-device making it impossible for mercury vapour to come into contact with either the copper tube or the multiplier in the event of an incident leading to the warming up of the traps. In case of a breakdown, the vacuum section is therefore brought up to atmospheric pressure by the introduction of nitrogen. (author) [French] Nous avons ete conduits pour la maintenance d'un spectrometre de masse type MS 5, dans le tube duquel il faut entretenir un vide de quelques 10{sup -7} mm de mercure, a etudier un systeme de remplissage automatique a intervalle de temps fixe des pieges en azote liquide. Ce remplissage se fait toutes les quatre heures. La presence dans l'enceinte sous vide, d'un multiplicateur d'electrons, nous a amenes a prevoir un systeme de securite evitant de mettre le tube en cuivre et le multiplicateur en contact avec la vapeur de mercure en cas d'incident amenant le rechauffage des pieges. En cas de panne, l'enceinte sous vide est donc ramenee a la pression atmospherique par une introduction d'azote. (auteur)

  10. Electrical conductivity and equation of state of liquid nitrogen, oxygen, benzene, and 1-butene shocked to 60 GPa

    Energy Technology Data Exchange (ETDEWEB)

    Hamilton, D.C.

    1986-10-08

    Measurements are reported for the electrical conductivity of liquid nitrogen (N/sub 2/), oxygen (O/sub 2/) and benzene (C/sub 6/H/sub 6/), and Hugoniot equation of state of liquid 1-butene (C/sub 4/H/sub 8/) under shock compressed conditions. The conductivity data span 7 x 10/sup -4/ to 7 x 10/sup 1/ ..cap omega../sup -1/cm/sup -1/ over a dynamic pressure range 18.1 to 61.5 GPa and are discussed in terms of amorphous semiconduction models which include such transport phenomena as hopping, percolation, pseudogaps, and metallization. Excellent agreement is found between the equation-of-state measurements, which span a dynamic pressure range 12.3 to 53.8 GPa, and Ree's calculated values which assume a 2-phase mixture consisting of molecular hydrogen and carbon in a dense diamond-like phase. There is a 2-1/2 fold increase in the thermal pressure contribution over a less dense, stoichiometrically equivalent liquid. 90 refs., 48 figs., 8 tabs.

  11. Outcome of bone recycling using liquid nitrogen as bone reconstruction procedure in malignant and recurrent benign aggressive bone tumour of distal tibia: A report of four cases.

    Science.gov (United States)

    Gede, Eka Wiratnaya I; Ida Ayu, Arrisna Artha; Setiawan I Gn, Yudhi; Aryana Ign, Wien; I Ketut, Suyasa; I Ketut, Siki Kawiyana; Putu, Astawa

    2017-01-01

    Amputation still considered as primary choice of malignancy treatment in distal tibia. Bone recycling with liquid nitrogen for reconstruction following resection of malignant bone tumours offers many advantages. We presented four patients with osteosarcoma, Ewing sarcoma, adamantinoma and recurrent giant cell tumour over distal tibia. All of the patients underwent wide excision and bone recycling using liquid nitrogen as bone reconstruction. The mean functional Musculoskeletal Tumor Society (MSTS) score was 75% with no infection and local recurrent. The reconstruction provides good local control and functional outcome.

  12. Local interfacial structure of subcooled boiling flow in a heated annulus

    International Nuclear Information System (INIS)

    Lee, Tae-Ho; Kim, Seong-O; Yun, Byong-Jo; Park, Goon-Cherl; Hibiki, Takashi

    2008-01-01

    Local measurements of flow parameters were performed for vertical upward subcooled boiling flows in an internally heated annulus. The annulus channel consisted of an inner heater rod with a diameter of 19.0 mm and an outer round tube with an inner diameter of 37.5 mm, and the hydraulic equivalent diameter was 18.5 mm. The double-sensor conductivity probe method was used for measuring the local void fraction, interfacial area concentration, bubble Sauter mean diameter and gas velocity, whereas the miniature Pitot tube was used for measuring the local liquid velocity. A total of 32 data sets were acquired consisting of various combinations of heat flux, 88.1-350.9 kW/m 2 , mass flux, 469.7-1061.4kg(m 2 s) and inlet liquid temperature, 83.8-100.5degC. Six existing drift-flux models, six exiting correlations of the interfacial area concentration and bubble layer thickness model were evaluated using the data obtained in the experiment. (author)

  13. Effects of nitrogen on corrosion of stainless steels in a liquid sodium environment

    International Nuclear Information System (INIS)

    Suzuki, Tadashi; Mutoh, Isao

    1990-01-01

    The corrosion of ferritic stainless steels using sodium at 650degC in a maximum isothermal region contained in a non-isothermal sodium loop constructed of a Type 316 stainless steel has been examined. Also, previous results on corrosion of austenitic stainless steels in sodium at 700degC in the same loop have been reproduced. The selective dissolution and absorption of nickel, the selective dissolution of chromium, and the resultant increase in iron in the surface of stainless steels in the loop mainly determine the corrosion loss of the stainless steel specimens. The austenitic steels hardly decarburize, but denitride. The ferritic steels decarburize and denitride and the denitriding is more remarkable than the decarburizing. The vanadium and niobium, carbide and nitride formers, in the ferritic steels inhibit the decarburizing to some extent, but barely inhibit the denitriding. The nitrogen in the steels rapidly diffuses to the grain boundaries, and rapidly dissolves into sodium, which will lower surface energy of the steels to enhance the dissolution of other elements. The dissolved N in sodium would then be transported to the free surface of the sodium adjacent to the argon cover gas of sodium and easily be released into the cover gas. This mechanism would cause the rapid dissolution of nitrogen into sodium and the enhancement of the corrosion rate of the steels containing nitrogen. (orig.)

  14. A dry-spot model of critical heat flux and transition boiling in pool and subcooled forced convection boiling

    International Nuclear Information System (INIS)

    Ha, Sang Jun

    1998-02-01

    A new dry-spot model for critical heat flux (CHF) is proposed. The new concept for dry area formation based on Poisson distribution of active nucleation sites and the critical active site number is introduced. The model is based on the boiling phenomena observed in nucleate boiling such as Poisson distribution of active nucleation sites and formation of dry spots on the heating surface. It is hypothesized that when the number of bubbles surrounding one bubble exceeds a critical number, the surrounding bubbles restrict the feed of liquid to the microlayer under the bubble. Then a dry spot of vapor will form on the heated surface. As the surface temperature is raised, more and more bubbles will have a population of surrounding active sites over the critical number. Consequently, the number of the spots will increase and the size of dry areas will increase due to merger of several dry spots. If this trend continues, the number of effective sites for heat transport through the wall will diminish, and CHF and transition boiling occur. The model is applicable to pool and subcooled forced convection boiling conditions, based on the common mechanism that CHF and transition boiling are caused by the accumulation and coalescences of dry spots. It is shown that CHF and heat flux in transition boiling can be determined without any empirical parameter based on information on the boiling parameters such as active site density and bubble diameter, etc., in nucleate boiling. It is also shown that the present model well represents actual phenomena on CHF and transition boiling and explains the mechanism on how parameters such as flow modes (pool or flow) and surface wettability influence CHF and transition boiling. Validation of the present model for CHF and transition boiling is achieved without any tuning parameter always present in earlier models. It is achieved by comparing the predictions of CHF and heat flux in transition boiling using measured boiling parameters in nucleate

  15. Two-phase wall function for modeling of turbulent boundary layer in subcooled boiling flow

    International Nuclear Information System (INIS)

    Bostjan Koncar; Borut Mavko; Yassin A Hassan

    2005-01-01

    Full text of publication follows: The heat transfer and phase-change mechanisms in the subcooled flow boiling are governed mainly by local multidimensional mechanisms near the heated wall, where bubbles are generated. The structure of such 'wall boiling flow' is inherently non-homogeneous and is further influenced by the two-phase flow turbulence, phase-change effects in the bulk, interfacial forces and bubble interactions (collisions, coalescence, break-up). In this work the effect of two-phase flow turbulence on the development of subcooled boiling flow is considered. Recently, the modeling of two-phase flow turbulence has been extensively investigated. A notable progress has been made towards deriving reliable models for description of turbulent behaviour of continuous (liquid) and dispersed phase (bubbles) in the bulk flow. However, there is a lack of investigation considering the modeling of two-phase flow boundary layer. In most Eulerian two-fluid models standard single-phase wall functions are used for description of turbulent boundary layer of continuous phase. That might be a good approximation at adiabatic flows, but their use for boundary layers with high concentration of dispersed phase is questionable. In this work, the turbulent boundary layer near the heated wall will be modeled with the so-called 'two-phase' wall function, which is based on the assumption of additional turbulence due to bubble-induced stirring in the boundary layer. In the two-phase turbulent boundary layer the wall function coefficients strongly depend on the void fraction. Moreover, in the turbulent boundary layer with nucleating bubbles, the bubble size variation also has a significant impact on the liquid phase. As a basis, the wall function of Troshko and Hassan (2001), developed for adiabatic bubbly flows will be used. The simulations will be performed by a general-purpose CFD code CFX-4.4 using additional models provided by authors. The results will be compared to the boiling

  16. Instrumentation for cryogenic magic angle spinning dynamic nuclear polarization using 90L of liquid nitrogen per day.

    Science.gov (United States)

    Albert, Brice J; Pahng, Seong Ho; Alaniva, Nicholas; Sesti, Erika L; Rand, Peter W; Saliba, Edward P; Scott, Faith J; Choi, Eric J; Barnes, Alexander B

    2017-10-01

    Cryogenic sample temperatures can enhance NMR sensitivity by extending spin relaxation times to improve dynamic nuclear polarization (DNP) and by increasing Boltzmann spin polarization. We have developed an efficient heat exchanger with a liquid nitrogen consumption rate of only 90L per day to perform magic-angle spinning (MAS) DNP experiments below 85K. In this heat exchanger implementation, cold exhaust gas from the NMR probe is returned to the outer portion of a counterflow coil within an intermediate cooling stage to improve cooling efficiency of the spinning and variable temperature gases. The heat exchange within the counterflow coil is calculated with computational fluid dynamics to optimize the heat transfer. Experimental results using the novel counterflow heat exchanger demonstrate MAS DNP signal enhancements of 328±3 at 81±2K, and 276±4 at 105±2K. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Effect of killer impurities on laser-excited barium-doped ZnS phosphors at liquid nitrogen temperature

    Science.gov (United States)

    Kumar, Sunil; Verma, N. K.; Bhatti, H. S.

    Zinc sulphide phosphors doped with Ba, as well as killer impurities of Fe, Co and Ni, having variable concentrations, were synthesized; and using an ultraviolet laser as the excitation source, decay-curve analyses were done. Various strong emissions in these phosphors were detected and the corresponding excited-state life times were measured at liquid nitrogen temperature. Studies were carried out to see the effect of killer impurities on the phosphorescence excited-state life times. Excited-state life times were found to decrease appreciably (microsecond to nanosecond) with the addition of quenchers. These studies are quite useful and find applications in areas such as optical memories, sensors, luminescent screens, laser-beam detection and alignment, color displays, printing, etc.

  18. Histopathological analysis of the therapeutic response to cryotherapy with liquid nitrogen in patients with multiple actinic keratosis.

    Science.gov (United States)

    Oliveira, Marina Câmara de; Trevisan, Flávia; Pinto, Clovis Antônio Lopes; Xavier, Célia Antônia; Pinto, Jaqueline Campoi Calvo Lopes

    2015-01-01

    Actinic keratoses are premalignant lesions of the skin caused by excessive sun exposure. Lesions may become mainly squamous cell carcinoma. Cryotherapy with liquid nitrogen is one of the main treatments. In order to evaluate the response of actinic keratosis to cryotherapy by histopathology, two lesions were selected in each of 14 patients with multiple actinic keratoses. In one lesion a biopsy was performed and in the other lesion a biopsy was performed after cryotherapy. Subsequently, both biopsies were compared histologically. Of the thirteen patients who completed the study, the best results were obtained in lesions undergoing cryotherapy concerning the atypia of keratinocytes, epithelial thickness and corneal layer and lymphocytic infiltrate. Despite the small number of patients, it was concluded that, if performed correctly, cryotherapy has high efficacy in the treatment of actinic keratoses.

  19. [In vitro activity of human bone marrow cells after cryopreservation in liquid nitrogen for 21 - 25 years].

    Science.gov (United States)

    Huang, You-Zhang; Shen, Jian-Liang; Gong, Li-Zhong; Zheng, Pei-Hao; Liu, Yi; Yin, Wen-Jie; Cen, Jian; Wang, Ning; Zhao, De-Feng

    2010-02-01

    The aim of this study was to investigate the best method to preserve human bone marrow cells and the effectiveness of long term cryopreservation at -80 degrees C. The human bone marrow cells in 20 samples were firstly frozen by a programmed freezer or -80 degrees C refrigerator, and then were preserved in liquid nitrogen with DMSO-AuP (10% dimethylsulfonamide, 10% autologous plasma) or DMSO-HES-HuA (5% dimethylsulfonamide, 6% hydroxyethyl starch, 4% human serum albumin) as cryoprotectant for 21 to 25 years. They were thawed in 38 degrees C. The cell sample frozen in -80 degrees C refrigerator was frozen at a low frozen speed of 1 degrees C/min which was the same as the programmed freezer before -30 degrees C. Before detection the bone marrow cells were taken from liquid nitrogen and were thawed in 38 degrees C, then the suspension of bone marrow cells was prepared for detection. The cell morphology and recovery rate of erythrocytes, nucleocytes and platelets; the recovery rate of hematopoietic stem progenitors cells, as well as mesenchymal stem cells were determined. The results showed that the protective effectiveness of DMSO-HES-HuA was better than DMSO-AuP. The mature erythrocytes were destroyed lightly [(3.5 +/- 1.5)% versus (12.6 +/- 4.8)%], the hemolysis rate was lower [(3.3 +/- 1.6)% versus (23.1 +/- 5.1)%]. Osmotic fragility of erythrocytes in the former was not changed, but was dropped in the latter. The recovery rates of red cell, platelet, granulocyte-macrophage colony forming units and long term culture-initiating cells were higher in the former than that in the latter [(96.1 +/- 1.8)%, (70.0 +/- 9.5)%, (49.2 +/- 10.9)%, (54.2 +/- 13.8)% versus (76.3 +/- 5.6)%, (52.7 +/- 8.1)%, (43.5 +/- 12.3)%, (47.2 +/- 13.6)% respectively]. With each kind of cryoprotectant or frozen method, the frozen MSC could keep the original growth properties. With the same cryoprotectant and different frozen method, the cryopreservative effectiveness was not different. The

  20. The cryoablation of lung tissue using liquid nitrogen in gel and in the ex vivo pig lung.

    Science.gov (United States)

    Nomori, Hiroaki; Yamazaki, Ikuo; Kondo, Toshiya; Kanno, Masaya

    2017-02-01

    To examine the efficiency of cryoablation using liquid nitrogen in lung tissue, we measured the size and temperature distribution of the frozen area (iceball) in gel and in the ex vivo pig lungs. Cryoprobes with diameters of 2.4 and 3.4 mm (2.4D and 3.4D, respectively) were used. Three temperature sensors were positioned at the surface of the cryoprobe and at distances of 0.5 and 1.5 cm from the cryoprobe. The ex vivo pig lungs were perfused with 37 °C saline and inflated using ventilator to simulate in vivo lung conditions. In gel, the 2.4D and 3.4D probes made iceballs of 3.9 ± 0.1 and 4.8 ± 0.3 cm in diameter, respectively, and the temperature at 1.5 cm from those probes reached -32 ± 8 and -53 ± 5 °C, respectively. In the pig lung, the 2.4D and 3.4D probes made iceballs of 5.2 ± 0.1 and 5.5 ± 0.4 cm in diameter, respectively, and the temperature at 1.5 cm from these probes reached -49 ± 5 and -58 ± 3 °C, respectively. Liquid nitrogen cryoablation using both 2.4D and 3.4D probes made iceballs that were of sufficient size, and effective temperatures were reached in both gel and the ex vivo pig lung.

  1. Changes in transcript expression patterns as a result of cryoprotectant treatment and liquid nitrogen exposure in Arabidopsis shoot tips.

    Science.gov (United States)

    Gross, Briana L; Henk, Adam D; Bonnart, Remi; Volk, Gayle M

    2017-03-01

    Transcripts related to abiotic stress, oxidation, and wounding were differentially expressed in Arabidopsis shoot tips in response to cryoprotectant and liquid nitrogen treatment. Cryopreservation methods have been implemented in genebanks as a strategy to back-up plant genetic resource collections that are vegetatively propagated. Cryopreservation is frequently performed using vitrification methods, whereby shoot tips are treated with cryoprotectant solutions, such as Plant Vitrification Solution 2 (PVS2) or Plant Vitrification Solution 3 (PVS3); these solutions remove and/or replace freezable water within the meristem cells. We used the model system Arabidopsis thaliana to identify suites of transcripts that are up- or downregulated in response to PVS2 and PVS3 treatment and liquid nitrogen (LN) exposure. Our results suggest that there are many changes in transcript expression in shoot tips as a result of cryoprotection and that these changes exceed the number detected as a result of LN exposure. In total, 180 transcripts showed significant changes in expression level unique to treatment with either the cryoprotectant or cryopreservation followed by recovery. Of these 180 transcripts, 67 were related to stress, defense, wounding, lipid, carbohydrate, abscisic acid, oxidation, temperature (cold/heat), or osmoregulation. The responses of five transcripts were confirmed using qPCR methods. The transcripts responding to PVS2 + LN suggest an oxidative response to this treatment, whereas the PVS3 + LN treatment invoked a more general metabolic response. This work shows that the choice of cryoprotectant can have a major influence on the patterns of transcript expression, presumably due to the level and extent of stress experienced by the shoot tip. As a result, there may be divergent responses of study systems to PVS2 and PVS3 treatments.

  2. Disappearance of a detached vapor mass in subcooled water

    International Nuclear Information System (INIS)

    Inada, Shigeaki; Miyasaka, Yoshiki; Izumi, Ryotaro.

    1986-01-01

    Experiments on pool transition boiling of water under atmospheric pressure on a heated surface 10 mm in diameter were conducted for subcooling 15 - 50 K. The mass flux of condensation of a detached coalescent vapor bubble was experimentally estimated by a mathematical model based on the mass transfer mechanism of condensation. As a result, it is clarified that the mass flux of condensation of the detached bubble was influenced by the initial growing velocity of a vapor bubble immediately following the detached bubble. The disappearance velocity of the detached bubble defined as a ratio of the bubble diameter at the departure to the time required until the disappearance, is in the range 0.2 to 2.0 m/sec. The disappearance velocity is proportional to the initial growing velocity of the bubble, to the square of the heat flux of the heated surface and to the cube of the wall superheat, separately. (author)

  3. Hydrophobic recovery of repeatedly plasma-treated silicone rubber .2. A comparison of the hydrophobic recovery in air, water, or liquid nitrogen

    NARCIS (Netherlands)

    Everaert, EP; VanderMei, HC; Busscher, HJ

    1996-01-01

    Surfaces of medical grade silicone rubber (Q7-4750, Dow Coming) were modified by repeated (six times) RF plasma treatments using various discharge gases: oxygen, argon, carbon dioxide, and ammonia. The treated samples were stored for a period of 3 months in ambient air, water, or liquid nitrogen.

  4. Liquid nitrogen or phenolization for giant cell tumor of bone?: a comparative cohort study of various standard treatments at two tertiary referral centers

    NARCIS (Netherlands)

    Heijden, L. van der; Geest, I.C.M. van der; Schreuder, H.W.B.; Sande, M.A.B. van der; Dijkstra, P.D.

    2014-01-01

    BACKGROUND: The rate of recurrence of giant cell tumor of bone is decreased by use of adjuvant treatments such as phenol, liquid nitrogen, or polymethylmethacrylate (PMMA) during curettage. We assessed recurrence and complication rates and functional outcome after curettage with use of phenol and

  5. Bubble and boundary layer behaviour in subcooled flow boiling

    Energy Technology Data Exchange (ETDEWEB)

    Maurus, Reinhold; Sattelmayer, Thomas [Lehrstuhl fuer Thermodynamik, Technische Universitaet Muenchen, 85747 Garching (Germany)

    2006-03-15

    Subcooled flow boiling is a commonly applied technique for achieving efficient heat transfer. In the study, an experimental investigation in the nucleate boiling regime was performed for water circulating in a closed loop at atmospheric pressure. The horizontal orientated test-section consists of a rectangular channel with a one side heated copper strip and good optical access. Various optical observation techniques were applied to study the bubble behaviour and the characteristics of the fluid phase. The bubble behaviour was recorded by the high-speed cinematography and by a digital high resolution camera. Automated image processing and analysis algorithms developed by the authors were applied for a wide range of mass flow rates and heat fluxes in order to extract characteristic length and time scales of the bubbly layer during the boiling process. Using this methodology, the bubbles were automatically analysed and the bubble size, bubble lifetime, waiting time between two cycles were evaluated. Due to the huge number of observed bubbles a statistical analysis was performed and distribution functions were derived. Using a two-dimensional cross-correlation algorithm, the averaged axial phase boundary velocity profile could be extracted. In addition, the fluid phase velocity profile was characterised by means of the particle image velocimetry (PIV) for the single phase flow as well as under subcooled flow boiling conditions. The results indicate that the bubbles increase the flow resistance. The impact on the flow exceeds by far the bubbly region and it depends on the magnitude of the boiling activity. Finally, the ratio of the averaged phase boundary velocity and of the averaged fluid velocity was evaluated for the bubbly region. (authors)

  6. Liquid nitrogen enhancement of partially annealed fission tracks in glass; and reply

    International Nuclear Information System (INIS)

    Wagner, G.A.; Carpenter, B.S.; Pilione, L.J.; Gold, D.P.

    1977-01-01

    Pilione and Gold (Nature 262: 773 (1976)) stated that it was possible to reveal partially annealed fission tracks in glass by immersion in liquid N 2 , and that it was possible to increase the total number of etchable tracks by increasing the immersion time. The present authors attempted to duplicate the work of the former authors using the same glass. They found no significant change in the number of etchable tracks after immersion in liquid N 2 , and they concluded that the latter has no effect on annealed tracks in glass. Any observed enhancement of partially annealed tracks is probably a surface effect and has no effect on the interior matrix of the glass. A reply by Pilione and Gold is appended. (U.K.)

  7. Use of liquid nitrogen during storage in a cell and tissue bank: contamination risk and effect on the detectability of potential viral contaminants.

    Science.gov (United States)

    Mirabet, Vicente; Alvarez, Manuel; Solves, Pilar; Ocete, Dolores; Gimeno, Concepción

    2012-04-01

    Cryopreservation is widely used for banking cells and tissues intended for transplantation. Liquid nitrogen provides a very stable ultra-low temperature environment. Thus, it is used for longterm storage. Unlike the exhaustive microbiological monitoring of the environmental conditions during tissue processing, storage is not usually considered as a critical point of potential contamination risk in professional standards for cell and tissue banking. We have analysed the presence of microbial agents inside our nitrogen tanks. We have mainly detected environmental and water-borne bacteria and fungi. In addition, we have studied the effect of liquid nitrogen exposure on virus detectability. Only differences for hepatitis C virus RNA were observed. Measures for contamination risk reduction during storage must be mandatory in cell and tissue banking. Copyright © 2011 Elsevier Inc. All rights reserved.

  8. Nitrogen injection in stagnant liquid metal. Eulerian-Eulerian and VOF calculations by fluent

    International Nuclear Information System (INIS)

    Pena, A.; Esteban, G.A.

    2004-01-01

    High power spallation sources are devices that can be very useful in different fields, as medicine, material science, and also in the Accelerator Driven Systems (ADS). This devices use Heavy Liquid Metals (HLM) as the spallation target. Furthermore, HLM are thought to be the coolant of those big energy sources produced by the process. Fast breeder reactors, advanced nuclear reactors, as well as the future designs of fusion reactors, also consider HLM as targets or coolants. Gas injection in liquid metal flows allows the enhancement of this coolant circulation. The difference in densities between the gas and the liquid metal is a big challenge for the multiphase models implemented in the Computational Fluid Dynamics (CFD) codes. Also the changing shape of the bubbles involves extra difficulties in the calculations. A N 2 flow in stagnant Lead-Bismuth eutectic (Pb-Bi), experiment available at Forschungszentrum Rossendorf e.V (FZR) in Germany, was used in one of the work-packages of the ASCHLIM project (EU contract number FIKW-CT-2001-80121). In this paper, calculations made by the UPV/EHU (University of the Basque Country) show measuring data compared with numerical results using the CFD (Computational Fluid Dynamics) code FLUENT and two multiphase models: the Eulerian-Eulerian and the Volume of Fluid (VOF). The interpretation of the experimental resulting velocities was difficult, because some parameters were not known, bubble trajectory and bubble shape, for example, as direct optical methods cannot be used, like it is done with water experiments. (author)

  9. Denitration of medium level liquid radioactive wastes by catalytic destruction of nitrogen oxides

    International Nuclear Information System (INIS)

    Donato, A.; Ricci, G.

    1984-01-01

    The catalytic abatement by means of NH 3 of the NOsub(x) produced in the radwaste conditioning has been studied. With reference to the gas produced in a bituminization plant, the thermodynamics and the chemistry of the NOsub(x) catalytic reduction to nitrogen and H 2 O have been evaluated. The following operational parameters have been experimentally studied: the catalyst bed temperature; the gas residence time; the vapour concentration; the NOsub(x) concentration; the gas velocity; the catalyst grain size distribution; the catalyst time-life. Abatement yields of the order of 99,5% have been obtained following experimental conditions must be selected. In the case of a bituminization plant, a NOsub(x) catalytic reactor, if installed between the evaporator denitrator and the condenser, could reduce to less than 1/100 the volume of the NaNO 3 secondary wastes produced by the gas scrubbing

  10. On the Partitioning of Wall Heat Flux in Subcooled Flow Boiling

    International Nuclear Information System (INIS)

    Chu, In-Cheol; Hoang, Nhan Hien; Euh, Dong-Jin; Song, Chul-Hwa

    2015-01-01

    This region has been treated successfully by two-fluid model coupled with a population balance model or interfacial area transport equation (IATE). The second region is near-wall heat transfer which has been commonly described by a wall heat flux partitioning model coupled with models of nucleation site density (NSD), bubble departure diameter and bubble release frequency. Since the phase change process in the near-wall heat transfer is really complex, comprising different heat transfer mechanisms, bubble dynamics, bubble nucleation and thermal response of heated surface, the modeling of the second region is still a great challenge despite intensive efforts. Numerous models and correlations have been proposed to aim for computing the near-wall heat transfer. The models of nucleation site density, bubble departure diameter and bubble release frequency are used to quantify these components. The models closely related to each other. The heat flux partitioning model controls the wall and liquid temperatures. Then, it turns to control the boiling parameters, i.e. nucleation site density, bubble departure diameter and bubble release frequency. In this study, the partitioning of wall heat flux is taken into account. The existing issues occurred with previous models of the heat flux partitioning are pointed out and then a new model which considers the heat transfer caused by evaporation of superheated liquid at bubble boundary and the actual period of transient conduction term is formulated. The new model is then validated with a collected experimental database. This paper presented a new heat flux partitioning model in which the heat transfer by evaporation of the superheated liquid at the bubble boundary and the active period of the transient conduction were considered. The new model was validated with the experimental data of the subcooled flow boiling of water obtained by Phillips

  11. Subcooled flow boiling heat transfer of ethanol aqueous solutions in vertical annulus space

    Directory of Open Access Journals (Sweden)

    Sarafraz M.M.

    2012-01-01

    Full Text Available The subcooled flow boiling heat-transfer characteristics of water and ethanol solutions in a vertical annulus have been investigated up to heat flux 132kW/m2. The variations in the effects of heat flux and fluid velocity, and concentration of ethanol on the observed heat-transfer coefficients over a range of ethanol concentrations implied an enhanced contribution of nucleate boiling heat transfer in flow boiling, where both forced convection and nucleate boiling heat transfer occurred. Increasing the ethanol concentration led to a significant deterioration in the observed heat-transfer coefficient because of a mixture effect, that resulted in a local rise in the saturation temperature of ethanol/water solution at the vapor-liquid interface. The reduction in the heat-transfer coefficient with increasing ethanol concentration is also attributed to changes in the fluid properties (for example, viscosity and heat capacity of tested solutions with different ethanol content. The experimental data were compared with some well-established existing correlations. Results of comparisons indicate existing correlations are unable to obtain the acceptable values. Therefore a modified correlation based on Gnielinski correlation has been proposed that predicts the heat transfer coefficient for ethanol/water solution with uncertainty about 8% that is the least in comparison to other well-known existing correlations.

  12. An investigation of transition boiling mechanisms of subcooled water under forced convective conditions

    Energy Technology Data Exchange (ETDEWEB)

    Kwang-Won, Lee; Sang-Yong, Lee

    1995-09-01

    A mechanistic model for forced convective transition boiling has been developed to investigate transition boiling mechanisms and to predict transition boiling heat flux realistically. This model is based on a postulated multi-stage boiling process occurring during the passage time of the elongated vapor blanket specified at a critical heat flux (CHF) condition. Between the departure from nucleate boiling (DNB) and the departure from film boiling (DFB) points, the boiling heat transfer is established through three boiling stages, namely, the macrolayer evaporation and dryout governed by nucleate boiling in a thin liquid film and the unstable film boiling characterized by the frequent touches of the interface and the heated wall. The total heat transfer rates after the DNB is weighted by the time fractions of each stage, which are defined as the ratio of each stage duration to the vapor blanket passage time. The model predictions are compared with some available experimental transition boiling data. The parametric effects of pressure, mass flux, inlet subcooling on the transition boiling heat transfer are also investigated. From these comparisons, it can be seen that this model can identify the crucial mechanisms of forced convective transition boiling, and that the transition boiling heat fluxes including the maximum heat flux and the minimum film boiling heat flux are well predicted at low qualities/high pressures near 10 bar. In future, this model will be improved in the unstable film boiling stage and generalized for high quality and low pressure situations.

  13. Prediction of subcooled flow boiling characteristics using two-fluid Eulerian CFD model

    Energy Technology Data Exchange (ETDEWEB)

    Braz Filho, Francisco A.; Ribeiro, Guilherme B., E-mail: gbribeiro@ieav.cta.br; Caldeira, Alexandre D.

    2016-11-15

    Highlights: • CFD multiphase model is used to predict subcooled flow boiling characteristics. • Better agreement is achieved for higher saturation pressures. • Onset of nucleate boiling and saturated boiling are well predicted. • CFD multiphase model tends to underestimate the void fraction. • Factors were adjusted in order to improve the void fraction results. - Abstract: The present study concerns a detailed analysis of flow boiling phenomena under high pressure systems using a two-fluid Eulerian approach provided by a Computational Fluid Dynamics (CFD) solver. For this purpose, a vertical heated pipe made of stainless steel with an internal diameter of 15.4 mm was considered as the modeled domain. Two different uniform heat fluxes and three saturation pressures were applied to the channel wall, whereas water mass flux of 900 kg/m{sup 2} s was considered for all simulation cases. The model was validated against a set of experimental data and results have indicated a promising use of the CFD technique for estimation of the wall temperature, the liquid bulk temperature and the location of the departure of nucleate boiling. Changes in factors applied in the modeling of the interfacial heat transfer coefficient and bubble departure frequency were suggested, allowing a better prediction of the void fraction along the heated channel. The commercial CFD solver FLUENT 14.5 was used for the model implementation.

  14. Prediction of subcooled flow boiling characteristics using two-fluid Eulerian CFD model

    International Nuclear Information System (INIS)

    Braz Filho, Francisco A.; Ribeiro, Guilherme B.; Caldeira, Alexandre D.

    2016-01-01

    Highlights: • CFD multiphase model is used to predict subcooled flow boiling characteristics. • Better agreement is achieved for higher saturation pressures. • Onset of nucleate boiling and saturated boiling are well predicted. • CFD multiphase model tends to underestimate the void fraction. • Factors were adjusted in order to improve the void fraction results. - Abstract: The present study concerns a detailed analysis of flow boiling phenomena under high pressure systems using a two-fluid Eulerian approach provided by a Computational Fluid Dynamics (CFD) solver. For this purpose, a vertical heated pipe made of stainless steel with an internal diameter of 15.4 mm was considered as the modeled domain. Two different uniform heat fluxes and three saturation pressures were applied to the channel wall, whereas water mass flux of 900 kg/m"2 s was considered for all simulation cases. The model was validated against a set of experimental data and results have indicated a promising use of the CFD technique for estimation of the wall temperature, the liquid bulk temperature and the location of the departure of nucleate boiling. Changes in factors applied in the modeling of the interfacial heat transfer coefficient and bubble departure frequency were suggested, allowing a better prediction of the void fraction along the heated channel. The commercial CFD solver FLUENT 14.5 was used for the model implementation.

  15. High-pressure (vapor + liquid) equilibria in the (nitrogen + n-heptane) system

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Sanchez, Fernando [Laboratorio de Termodinamica, Programa de Ingenieria Molecular, Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas 152, 07730 Mexico, D.F. (Mexico)]. E-mail: fgarcias@imp.mx; Eliosa-Jimenez, Gaudencio [Laboratorio de Termodinamica, Programa de Ingenieria Molecular, Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas 152, 07730 Mexico, D.F. (Mexico); Silva-Oliver, Guadalupe [Laboratorio de Termodinamica, Programa de Ingenieria Molecular, Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas 152, 07730 Mexico, D.F. (Mexico); Godinez-Silva, Armando [Laboratorio de Termodinamica, Programa de Ingenieria Molecular, Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas 152, 07730 Mexico, D.F. (Mexico)

    2007-06-15

    In this work, new (vapor + liquid) equilibrium data for the (N{sub 2} + n-heptane) system were experimentally measured over a wide temperature range from (313.6 to 523.7) K and pressures up to 50 MPa. A static-analytic apparatus with visual sapphire windows and pneumatic capillary samplers was used in the experimental measurements. Equilibrium phase compositions and (vapor + liquid) equilibrium ratios are reported. The new results were compared with those reported by other authors. The comparison showed that the pressure-composition data reported in this work are less scattered than those determined by others. Hence, the results demonstrate the reliability of the experimental apparatus at high temperatures and pressures. The experimental data were represented with the PR and PC-SAFT equations of state by using one-fluid mixing rules and a single temperature independent interaction parameter. Results of the representation showed that the PC-SAFT equation was superior to the PR equation in correlating the experimental data of the (N{sub 2} + n-heptane) system.

  16. High-pressure (vapor + liquid) equilibria in the (nitrogen + n-heptane) system

    International Nuclear Information System (INIS)

    Garcia-Sanchez, Fernando; Eliosa-Jimenez, Gaudencio; Silva-Oliver, Guadalupe; Godinez-Silva, Armando

    2007-01-01

    In this work, new (vapor + liquid) equilibrium data for the (N 2 + n-heptane) system were experimentally measured over a wide temperature range from (313.6 to 523.7) K and pressures up to 50 MPa. A static-analytic apparatus with visual sapphire windows and pneumatic capillary samplers was used in the experimental measurements. Equilibrium phase compositions and (vapor + liquid) equilibrium ratios are reported. The new results were compared with those reported by other authors. The comparison showed that the pressure-composition data reported in this work are less scattered than those determined by others. Hence, the results demonstrate the reliability of the experimental apparatus at high temperatures and pressures. The experimental data were represented with the PR and PC-SAFT equations of state by using one-fluid mixing rules and a single temperature independent interaction parameter. Results of the representation showed that the PC-SAFT equation was superior to the PR equation in correlating the experimental data of the (N 2 + n-heptane) system

  17. Transient pool boiling heat transfer due to increasing heat inputs in subcooled water at high pressures

    Energy Technology Data Exchange (ETDEWEB)

    Fukuda, K. [Kobe Univ. of Mercantile Marine (Japan); Shiotsu, M.; Sakurai, A. [Kyoto Univ. (Japan)

    1995-09-01

    Understanding of transient boiling phenomenon caused by increasing heat inputs in subcooled water at high pressures is necessary to predict correctly a severe accident due to a power burst in a water-cooled nuclear reactor. Transient maximum heat fluxes, q{sub max}, on a 1.2 mm diameter horizontal cylinder in a pool of saturated and subcooled water for exponential heat inputs, q{sub o}e{sup t/T}, with periods, {tau}, ranging from about 2 ms to 20 s at pressures from atmospheric up to 2063 kPa for water subcoolings from 0 to about 80 K were measured to obtain the extended data base to investigate the effect of high subcoolings on steady-state and transient maximum heat fluxes, q{sub max}. Two main mechanisms of q{sub max} exist depending on the exponential periods at low subcoolings. One is due to the time lag of the hydrodynamic instability which starts at steady-state maximum heat flux on fully developed nucleate boiling (FDNB), and the other is due to the heterogenous spontaneous nucleations (HSN) in flooded cavities which coexist with vapor bubbles growing up from active cavities. The shortest period corresponding to the maximum q{sub max} for long period range belonging to the former mechanism becomes longer and the q{sub max}mechanism for long period range shifts to that due the HSN on FDNB with the increase of subcooling and pressure. The longest period corresponding to the minimum q{sub max} for the short period range belonging to the latter mechanism becomes shorter with the increase in saturated pressure. On the contrary, the longest period becomes longer with the increase in subcooling at high pressures. Correlations for steady-state and transient maximum heat fluxes were presented for a wide range of pressure and subcooling.

  18. Transient pool boiling heat transfer due to increasing heat inputs in subcooled water at high pressures

    International Nuclear Information System (INIS)

    Fukuda, K.; Shiotsu, M.; Sakurai, A.

    1995-01-01

    Understanding of transient boiling phenomenon caused by increasing heat inputs in subcooled water at high pressures is necessary to predict correctly a severe accident due to a power burst in a water-cooled nuclear reactor. Transient maximum heat fluxes, q max , on a 1.2 mm diameter horizontal cylinder in a pool of saturated and subcooled water for exponential heat inputs, q o e t/T , with periods, τ, ranging from about 2 ms to 20 s at pressures from atmospheric up to 2063 kPa for water subcoolings from 0 to about 80 K were measured to obtain the extended data base to investigate the effect of high subcoolings on steady-state and transient maximum heat fluxes, q max . Two main mechanisms of q max exist depending on the exponential periods at low subcoolings. One is due to the time lag of the hydrodynamic instability which starts at steady-state maximum heat flux on fully developed nucleate boiling (FDNB), and the other is due to the heterogenous spontaneous nucleations (HSN) in flooded cavities which coexist with vapor bubbles growing up from active cavities. The shortest period corresponding to the maximum q max for long period range belonging to the former mechanism becomes longer and the q max mechanism for long period range shifts to that due the HSN on FDNB with the increase of subcooling and pressure. The longest period corresponding to the minimum q max for the short period range belonging to the latter mechanism becomes shorter with the increase in saturated pressure. On the contrary, the longest period becomes longer with the increase in subcooling at high pressures. Correlations for steady-state and transient maximum heat fluxes were presented for a wide range of pressure and subcooling

  19. Insulation effect on thermal stability of Coated Conductors wires in liquid nitrogen

    Science.gov (United States)

    Rubeli, Thomas; Dutoit, Bertrand; Martynova, Irina; Makarevich, Artem; Molodyk, Alexander; Samoilenkov, Sergey

    2017-02-01

    Superconducting wires are not perfectly homogeneous in term of critical current as well as stabilization. In resistive fault current limiter applications this could lead to hot spots if the fault current is only slightly above the nominal current of the device. Increasing stabilization by using thicker silver coating for example may prevent this problem but this method implies longer wire length to maintain the same impedance during a fault. Very efficient cooling in another way to prevent hot spots, this can be achieved in nucleate boiling regime. Optimal insulation can be used to prevent film boiling regime, staying in nucleate boiling regime in a much broader temperature range. In this work a novel technique is used to monitor in real time the temperature of the wire during the quench. Using this method several increasing insulation thicknesses are tested, measuring for each the heat exchange rate to the nitrogen bath. Exchange rate measurements are made in quasistatic regime and during the re-cooling of the wire. SuperOx wires provided with different insulation thicknesses exhibit an excellent stability, far above a bare wire. On the other side, for very thick insulations the stability gain is lost. Re-cooling speeds dependency on insulation thicknesses is measured too.

  20. Development of Bubble Lift-off Diameter Model for Subcooled Boiling Flows

    International Nuclear Information System (INIS)

    Hoang, Nhan Hien; Chu, Incheol; Song Chulhwa; Euh, Dongjin

    2014-01-01

    A lot of models and correlations for predicting the bubble departure/lift-off diameter are available in the literature. Most of them were developed based on a hydrodynamic principle, which balances forces acting on a bubble at the departure/lift-off point. One difficulty of these models is lack of essential information, such as bubble front velocity, liquid velocity, or relative velocity, to estimate the active force elements. Hence, the lift-off bubble diameter predicted by these hydrodynamic-controlled models may be suffered a large uncertainty. In contract to the hydrodynamic approach, there are few models developed based on the heat transfer aspect. By balancing the heat conducted through a microlayer underneath a bubble with the heat taken away by condensation at the upper part of the bubble, Unal derived a heat-controlled model of the bubble lift-off diameter. This model did not consider the role of superheat liquid layer surrounding the bubble as well as the effect of liquid properties on the heat transfer process. Beside these two approaches, several empirical correlations have been proposed based on dimensionless analyses for measured experimental databases. The application of these correlations to different experiments conditions is, of course, questionable because of the lack of physical bases. Regarding the heat transfer accompanied by a vapor bubble, four involved heat transfer regions surrounding this bubble can be defined as in Fig. 1. These are dry region, microlayer, superheated liquid layer (SpLL) and subcooled liquid layer (SbLL). The existing of the microlayer is confirmed by experiments, and it is considered to be very effective in the heat transfer. Sernas and Hoper defined five types of the microlayer and indicated that the microlayer acting as a very thick liquid layer gives a best prediction for the bubble growth. However, beside the microlayer, the SpLL might play an important role in the heat transfer if its effective heat transfer area

  1. LC-MS/MS analysis of uncommon paracetamol metabolites derived through in vitro polymerization and nitration reactions in liquid nitrogen.

    Science.gov (United States)

    Trettin, Arne; Jordan, Jens; Tsikas, Dimitrios

    2014-09-01

    Paracetamol (acetaminophen, APAP) is a commonly used analgesic drug. Known paracetamol metabolites include the glucuronide, sulfate and mercapturate. N-Acetyl-benzoquinonimine (NAPQI) is considered the toxic intermediate metabolite of paracetamol. In vitro and in vivo studies indicate that paracetamol is also metabolized to additional poorly characterized metabolites. For example, metabolomic studies in urine samples of APAP-treated mice revealed metabolites such as APAP-sulfate-APAP and APAP-S-S-APAP in addition to the classical phase II metabolites. Here, we report on the development and application of LC-MS and LC-MS/MS approaches to study reactions of unlabelled and (2)H-labelled APAP with unlabelled and (15)N-labelled nitrite in aqueous phosphate buffers (pH 7.4) upon their immersion into liquid nitrogen (-196°C). In mechanistic studies, these reactions were also studied in aqueous buffer prepared in (18)O-labelled water. LC-MS and LC-MS/MS analyses were performed on a reverse-phase material (C18) using gradient elution (2mM ammonium acetate/acetonitrile), in positive and negative electrospray mode. We identified a series of APAP metabolites including di-, tri- and tetra-APAP, mono- and di-nitro-APAP and nitric ester of di-APAP. Our study indicates that nitrite induces oxidation, i.e., polymerization and nitration of APAP, when buffered APAP/nitrite solutions are immersed into liquid nitrogen. These reactions are specific for nitrite with respect to nitrate and do not proceed via intermediate formation of NAPQI. Potassium ions and physiological saline but not thiols inhibit nitrite- and shock-freeze-induced reactions of paracetamol. The underlying mechanism likely involves in situ formation of NO2 radicals from nitrite secondary to profound pH reduction (down to pH 1) and disproportionation. Polymeric paracetamol species can be analyzed as pentafluorobenzyl derivatives by LC-MS but not by GC-MS. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. Theoretical analysis and experimental investigation on performance of the thermal shield of accelerator cryomodules by thermo-siphon cooling of liquid nitrogen

    Science.gov (United States)

    Datta, T. S.; Kar, S.; Kumar, M.; Choudhury, A.; Chacko, J.; Antony, J.; Babu, S.; Sahu, S. K.

    2015-12-01

    Five beam line cryomodules with total 27 superconducting Radio Frequency (RF) cavities are installed and commissioned at IUAC to enhance the energy of heavy ion from 15 UD Pelletron. To reduce the heat load at 4.2 K, liquid nitrogen (LN2) cooled intermediate thermal shield is used for all these cryomodules. For three linac cryomodules, concept of forced flow LN2 cooling is used and for superbuncher and rebuncher, thermo-siphon cooling is incorporated. It is noticed that the shield temperature of superbuncher varies from 90 K to 110 K with respect to liquid nitrogen level. The temperature difference can't be explained by using the basic concept of thermo-siphon with the heat load on up flow line. A simple thermo-siphon experimental set up is developed to simulate the thermal shield temperature profile. Mass flow rate of liquid nitrogen is measured with different heat load on up flow line for different liquid levels. It is noticed that small amount of heat load on down flow line have a significant effect on mass flow rate. The present paper will be investigating the data generated from the thermosiphon experimental set up and a theoretical analysis will be presented here to validate the measured temperature profile of the cryomodule shield.

  3. Investigation of transient chill down phenomena in tubes using liquid nitrogen

    Science.gov (United States)

    Shukla, A. K.; Sridharan, Arunkumar; Atrey, M. D.

    2017-12-01

    Chill down of cryogenic transfer lines is a crucial part of cryogenic propulsion as chill down ensures transfer of single phase fluid to the storage tanks of cryogenic engines. It also ensures single phase liquid flow at the start of the engine. Chill down time depends on several parameters such as length of the pipe, pipe diameter, orientation, mass flux etc. To understand the effect of these parameters, experiments are carried out in a set up designed and fabricated at Indian Institute of Technology Bombay using tubes of two different diameters. Experiments are conducted at different inlet pressures and mass flow rate values to understand their effect. Two different pipe sizes are taken to study the effect of variation in diameter on chill down time and quantity of cryogen required. Different orientations are taken to understand their effect on the chill down time, heat transfer coefficient and critical heat flux for the same inlet pressure and mass flux. Pipe inner wall temperature, heat transfer coefficient for different boiling regimes and critical heat flux are calculated based on measured outer surface temperature history for each case. A one dimensional energy conservation equation is solved for transient chill down process considering constant mass flux and inlet pressure to predict the chill down time. Temperature variation during chill down obtained from the numerical simulations are compared with the measured temperature history.

  4. Research on Flow Pattern of Nitrogen Tetroxide Liquid in the Different Bend Radii Pipes

    Directory of Open Access Journals (Sweden)

    Hao Pengfei

    2016-01-01

    Full Text Available N2O4 is a common rocket fuel propellants, it has the characteristics of low boiling point and a large viscosity , the friction between viscosity fluids and pipeline dramatic leads to a huge sticky heat, therefore, the vaporization phenomenon often occurs in the pipeline, particularly in bending of the viscous heat. For this reason, the research of the different bending radii vaporized fluid conditions for optimizing the piping and precise the filling flow is significant. In this paper, the MIXTURE mixed flow model is used to achieve the numerical simulation the pipelines filling of the three different bending radii, it still have not solved the mass transfer problem between the different phases. Therefore, the custom functions are needed to define the mass transfer problems from the liquid phase to the vapor phase. Though the contrast among the volume phase cloud of six different elbow models , we have the following conclusions: 1 In the entire pipeline transportation, the distribution vaporization rate from the inlet pipe to the outlet pipe follows the distribution of the first increasing and then decreasing, the gas rates of the elbow area is highest; 2Analyzing the sticky heat for different bend radii, we have the conclusion that the lowest bending vaporization the of the optimal radius is 0.45m. The above conclusions are drawn in good agreement with the actual law, can effectively guide the engineering practice, have important significance for the future design for the optimization of the fuel pipeline transportation.

  5. Thermodynamic models for vapor-liquid equilibria of nitrogen + oxygen + carbon dioxide at low temperatures

    Science.gov (United States)

    Vrabec, Jadran; Kedia, Gaurav Kumar; Buchhauser, Ulrich; Meyer-Pittroff, Roland; Hasse, Hans

    2009-02-01

    For the design and optimization of CO 2 recovery from alcoholic fermentation processes by distillation, models for vapor-liquid equilibria (VLE) are needed. Two such thermodynamic models, the Peng-Robinson equation of state (EOS) and a model based on Henry's law constants, are proposed for the ternary mixture N 2 + O 2 + CO 2. Pure substance parameters of the Peng-Robinson EOS are taken from the literature, whereas the binary parameters of the Van der Waals one-fluid mixing rule are adjusted to experimental binary VLE data. The Peng-Robinson EOS describes both binary and ternary experimental data well, except at high pressures approaching the critical region. A molecular model is validated by simulation using binary and ternary experimental VLE data. On the basis of this model, the Henry's law constants of N 2 and O 2 in CO 2 are predicted by molecular simulation. An easy-to-use thermodynamic model, based on those Henry's law constants, is developed to reliably describe the VLE in the CO 2-rich region.

  6. Thermal Performance of Low Layer Density Multilayer Insu1ation Using Liquid Nitrogen

    Science.gov (United States)

    Johnson, Wesley L.; Fesmire, James E.

    2011-01-01

    In order to support long duration cryogenic propellant storage, the Cryogenic Fluid Management (CFM) Project of the Exploration Technology Development Program (ETDP) is investigating the long duration storage propertie$ of liquid methane on the lunar surface. The Methane Lunar Surface Thermal Control (MLSTC) testing is using a tank of the approximate dimensions of the Altair ascent tanks inside of a vacuum chamber to simulate the environment in low earth orbit and on the lunar surface. The thermal performance testing of multilayer insulation (MLI) coupons that are fabricated identically to the tank applied insulation is necessary to understand the performance of the blankets and to be able to predict the performance of the insulation prior to testing. This coupon testing was completed in Cryostat-100 at the Cryogenics Test Laboratory. The results showed the properties of the insulation as a function of layer density, number of layers, and warm boundary temperature. These results aid in the understanding of the performance parameters o fMLI and help to complete the body of literature on the topic.

  7. Development and test of an axial flux type PM synchronous motor with liquid nitrogen cooled HTS armature windings

    International Nuclear Information System (INIS)

    Sugimoto, H; Morishita, T; Tsuda, T; Takeda, T; Togawa, H; Oota, T; Ohmatsu, K; Yoshida, S

    2008-01-01

    We developed an axial gap permanent magnet type superconducting synchronous motor cooled by liquid nitrogen (LN 2 ). The motor includes 8 poles and 6 armature windings. The armature windings are made from BSCCO wire operated at the temperature level between 66K∼70K. The design of the rated output is 400kW at 250rpm. Because HTS wires produce AC loss, there are few motors developed with a superconducting armature winding. In a large capacity motor, HTS windings need to be connected in parallel way. However, the parallel connection causes different current flowing to each HTS winding. To solve this problem, we connected a current distributor to the motor. As a result, not only the current difference can be suppressed, but also the current of each winding can be adjusted freely. The low frequency and less flux penetrating HTS wire because of current distributor contribute to low AC loss. This motor is an axial gap rotating-field one, the cooling parts are fixed. This directly leads to simple cooling system. The motor is also brushless. This paper presents the structure, the analysis of the motor and the tests

  8. Integrity of chromatin and replicating DNA in nuclei released from fission yeast by semi-automated grinding in liquid nitrogen

    Science.gov (United States)

    2011-01-01

    Background Studies of nuclear function in many organisms, especially those with tough cell walls, are limited by lack of availability of simple, economical methods for large-scale preparation of clean, undamaged nuclei. Findings Here we present a useful method for nuclear isolation from the important model organism, the fission yeast, Schizosaccharomyces pombe. To preserve in vivo molecular configurations, we flash-froze the yeast cells in liquid nitrogen. Then we broke their tough cell walls, without damaging their nuclei, by grinding in a precision-controlled motorized mortar-and-pestle apparatus. The cryo-ground cells were resuspended and thawed in a buffer designed to preserve nuclear morphology, and the nuclei were enriched by differential centrifugation. The washed nuclei were free from contaminating nucleases and have proven well-suited as starting material for genome-wide chromatin analysis and for preparation of fragile DNA replication intermediates. Conclusions We have developed a simple, reproducible, economical procedure for large-scale preparation of endogenous-nuclease-free, morphologically intact nuclei from fission yeast. With appropriate modifications, this procedure may well prove useful for isolation of nuclei from other organisms with, or without, tough cell walls. PMID:22088094

  9. Processing Adipose-Rich Mohs Samples: A Comparative Study of Effectiveness of Pretreatment With Liquid Nitrogen Versus Flash Freezing Spray.

    Science.gov (United States)

    Reserva, Jeave; Kozel, Zachary; Krol, Cindy; Speiser, Jodi; Adams, William; Tung, Rebecca

    2017-11-01

    Processing of adipose-rich Mohs micrographic surgery (MMS) specimens poses challenges that may preclude complete margin evaluation. In this setting, the value of additional freezing methods using various cooling agents has not been previously investigated. The aim of this study is to compare the frozen section quality of high-adipose Mohs specimens processed without additional cooling treatments versus those pretreated with 1,1,1,2-tetrafluoroethane (TFE) or liquid nitrogen (LN2). A set of 3 sections were each taken from 24 adipose-rich Mohs micrographic surgery specimens. A section from each set was subjected to either no additional cooling treatment (control), two 10-second pulse sprays of 1,1,1,2-tetrafluoroethane, or three 2-second pulse sprays of LN2. After staining, 2 blinded raters evaluated slide quality based on the presence or absence of the following features: margin completeness, nuclear clearing, epidermal or adipose folding, holes, or venetian blind-like artifacts. Pretreatment of the sample with LN2 produced a significantly (P < 0.001) greater number of high-quality slides (19/24) compared to pretreatment with 1,1,1,2-tetrafluoroethane (1/24) and no additional treatment (0/24). The adjunctive use of LN2 spray before tissue embedding circumvents the challenges of processing "thick" (high-adipose) specimens and facilitates the production of high-quality frozen section slides during Mohs micrographic surgery.

  10. Efficacy of liquid nitrogen cryotherapy for Barrett's esophagus after endoscopic resection of intramucosal cancer: A multicenter study.

    Science.gov (United States)

    Trindade, Arvind J; Pleskow, Douglas K; Sengupta, Neil; Kothari, Shivangi; Inamdar, Sumant; Berkowitz, Joshua; Kaul, Vivek

    2018-02-01

    Liquid nitrogen cryotherapy (LNC) allows increased depth of ablation compared with radiofrequency ablation in Barrett's esophagus (BE). Expert centers may use LNC over radiofrequency ablation to ablate Barrett's esophagus after endoscopic resection of intramucosal cancer (IMCA). The aim of our study was to (1) evaluate the safety and efficacy of LNC ablation in patients with BE and IMCA and (2) to evaluate the progression to invasive disease despite therapy. This was a multicenter, retrospective study of consecutive patients with BE who received LNC following endoscopic mucosal resection (EMR) of IMCA. The outcomes evaluated were complete eradication of dysplasia and intestinal metaplasia and development of invasive cancer during follow up. The follow-up period was at least 1 year from initial LNC. Twenty-seven patients were identified. The median Prague score was C3M5 (range C0M1-C14M14). After EMR+LNC, the median Prague score was C0M1 (range C0M0-C9M10); 22/27 patients (82%) achieved complete eradication of dysplasia after cryotherapy, and 19/27 patients (70%) achieved complete eradication of intestinal metaplasia. One out of 27 patients (4%) developed invasive cancer (disease beyond IMCA) over the study period. Cryotherapy is an effective endoscopic tool for eradication of BE dysplasia after EMR for IMCA. Development of invasive cancer is low for this high-risk group. © 2017 Journal of Gastroenterology and Hepatology Foundation and John Wiley & Sons Australia, Ltd.

  11. Integrity of chromatin and replicating DNA in nuclei released from fission yeast by semi-automated grinding in liquid nitrogen.

    Science.gov (United States)

    Givens, Robert M; Mesner, Larry D; Hamlin, Joyce L; Buck, Michael J; Huberman, Joel A

    2011-11-16

    Studies of nuclear function in many organisms, especially those with tough cell walls, are limited by lack of availability of simple, economical methods for large-scale preparation of clean, undamaged nuclei. Here we present a useful method for nuclear isolation from the important model organism, the fission yeast, Schizosaccharomyces pombe. To preserve in vivo molecular configurations, we flash-froze the yeast cells in liquid nitrogen. Then we broke their tough cell walls, without damaging their nuclei, by grinding in a precision-controlled motorized mortar-and-pestle apparatus. The cryo-ground cells were resuspended and thawed in a buffer designed to preserve nuclear morphology, and the nuclei were enriched by differential centrifugation. The washed nuclei were free from contaminating nucleases and have proven well-suited as starting material for genome-wide chromatin analysis and for preparation of fragile DNA replication intermediates. We have developed a simple, reproducible, economical procedure for large-scale preparation of endogenous-nuclease-free, morphologically intact nuclei from fission yeast. With appropriate modifications, this procedure may well prove useful for isolation of nuclei from other organisms with, or without, tough cell walls.

  12. Integrity of chromatin and replicating DNA in nuclei released from fission yeast by semi-automated grinding in liquid nitrogen

    Directory of Open Access Journals (Sweden)

    Givens Robert M

    2011-11-01

    Full Text Available Abstract Background Studies of nuclear function in many organisms, especially those with tough cell walls, are limited by lack of availability of simple, economical methods for large-scale preparation of clean, undamaged nuclei. Findings Here we present a useful method for nuclear isolation from the important model organism, the fission yeast, Schizosaccharomyces pombe. To preserve in vivo molecular configurations, we flash-froze the yeast cells in liquid nitrogen. Then we broke their tough cell walls, without damaging their nuclei, by grinding in a precision-controlled motorized mortar-and-pestle apparatus. The cryo-ground cells were resuspended and thawed in a buffer designed to preserve nuclear morphology, and the nuclei were enriched by differential centrifugation. The washed nuclei were free from contaminating nucleases and have proven well-suited as starting material for genome-wide chromatin analysis and for preparation of fragile DNA replication intermediates. Conclusions We have developed a simple, reproducible, economical procedure for large-scale preparation of endogenous-nuclease-free, morphologically intact nuclei from fission yeast. With appropriate modifications, this procedure may well prove useful for isolation of nuclei from other organisms with, or without, tough cell walls.

  13. Multi-scale full-field measurements and near-wall modeling of turbulent subcooled boiling flow using innovative experimental techniques

    Energy Technology Data Exchange (ETDEWEB)

    Hassan, Yassin A., E-mail: y-hassan@tamu.edu

    2016-04-01

    Highlights: • Near wall full-field velocity components under subcooled boiling were measured. • Simultaneous shadowgraphy, infrared thermometry wall temperature and particle-tracking velocimetry techniques were combined. • Near wall velocity modifications under subcooling boiling were observed. - Abstract: Multi-phase flows are one of the challenges on which the CFD simulation community has been working extensively with a relatively low success. The phenomena associated behind the momentum and heat transfer mechanisms associated to multi-phase flows are highly complex requiring resolving simultaneously for multiple scales on time and space. Part of the reasons behind the low predictive capability of CFD when studying multi-phase flows, is the scarcity of CFD-grade experimental data for validation. The complexity of the phenomena and its sensitivity to small sources of perturbations makes its measurements a difficult task. Non-intrusive and innovative measuring techniques are required to accurately measure multi-phase flow parameters while at the same time satisfying the high resolution required to validate CFD simulations. In this context, this work explores the feasible implementation of innovative measuring techniques that can provide whole-field and multi-scale measurements of two-phase flow turbulence, heat transfer, and boiling parameters. To this end, three visualization techniques are simultaneously implemented to study subcooled boiling flow through a vertical rectangular channel with a single heated wall. These techniques are listed next and are used as follow: (1) High-speed infrared thermometry (IR-T) is used to study the impact of the boiling level on the heat transfer coefficients at the heated wall, (2) Particle Tracking Velocimetry (PTV) is used to analyze the influence that boiling parameters have on the liquid phase turbulence statistics, (3) High-speed shadowgraphy with LED illumination is used to obtain the gas phase dynamics. To account

  14. Thermal interaction effect on nucleation site distribution in subcooled boiling

    International Nuclear Information System (INIS)

    Zou, Ling; Jones, Barclay

    2012-01-01

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

  15. Study of the initiation of subcooled boiling during power transients

    International Nuclear Information System (INIS)

    VanVleet, R.J.

    1985-01-01

    An experimental investigation of boiling initiation during power transients has been conducted for horizontal-cylinder heating elements in degassed distilled water. Platinum elements, 0.127 and 0.250 mm in diameter, were internally heated electrically at a controlled superficial heat flux (power applied divided by surface area) increasing linearly with time at rates of 0.035 and 0.35 MW/m 2 s and corresponding test durations of 20 and 2 seconds. Tests were carried out at saturation temperatures from 100 to 195 0 C with bulk fluid subcooling from 0 to 30 K. During the course of a power transient, element temperature and superficial heat flux were measured electrically and the boiling initiation time was determined optically. It was found that the conditions for boiling initiation depended strongly on the pressure-temperature history of the heating element and surround fluid prior to the transient. Boiling initiation times were found to agree qualitatively with predictions of a model based on the contact-angle hysteresis concept. Brief prepressurization prior to a transient was found to increase dramatically the temperature and heat flux required for boiling initiation because of deactivation of boiling initiation sites. However, sites were re-activated during the transient and, in subsequent tests without prepressurization, no elevation in boiling initiation conditions was observed and results were in quantitative agreement with predictions of the model

  16. A modified Bernoulli equation for the calculation of the fluid dynamics of the region of subcooled water

    International Nuclear Information System (INIS)

    Pana, P.

    1975-12-01

    A mathematical model is derived to describe the fluid-dynamics for the region of subcooled water. The qualitative changes, when crossing the saturation line, from the wet-steam region to the subcooled region, are discussed with respect to thermodynamical considerations, and the change of state in the subcooled region is treated detailled, showing the limitation of validity for the theoretical model. (orig./TK) [de

  17. Efficient operation of the liquid nitrogen supply station for the cryogenic equipment of the pilot plant for tritium and deuterium separation

    International Nuclear Information System (INIS)

    Gherghinescu, Sorin; Popescu, Gheorghe

    2009-01-01

    Full text: At liquid nitrogen temperature the materials lose their elastic properties and become brittle. Protecting the personnel working with liquid nitrogen becomes difficult and to avoid accidents special equipment is used as helmets, gloves, goggles, special footwear, etc. The liquid nitrogen can destroy insulation of electrical cables, and so short circuits and electrocution can occur. Objects made of carbon steel (like pipes, props, containers, pillars, metal roofs, etc) when cooled by a sufficient amount of cryogenic liquid can break down to minimal mechanical stresses. Exceedingly dangerous is liquid nitrogen entered and retained into carbon steel ducts carrying pressured gas (even et low pressure values), since their cooling at extremely low temperatures can provoke their explosion. Resulting pieces and fragments are dangerous for both personnel and equipment around. The gas components of atmosphere (oxygen, nitrogen, argon) have critical parameters which allow liquefaction only at high pressure. For this reason they are called 'permanent gases'. Consequently, transformed in cryogenic liquids in closed precincts these gases will get totally vaporised when the precincts are not properly thermally isolated. The resulting raised pressure can lead to precinct destruction. For instance such event happens when an amount of liquid nitrogen is isolated into an external pipe between two closed taps while a relief valve is not in place. In such conditions isolation of liquid nitrogen ducts is absolutely necessary. This report reviews various solutions for obtaining an efficient isolation. All thermal isolations aim at reducing the heat transfer. In cryogenics the heat transfer from environment to the fluid in liquid phase is an important factor affecting the efficiency and yield of the liquefaction system. Choosing the type of isolation depends essentially on the specific application. The factors which must be considered are the cooling power, weight, the

  18. Two-phase flow characteristics of liquid nitrogen in vertically upward 0.5 and 1.0 mm micro-tubes: Visualization studies

    Science.gov (United States)

    Zhang, P.; Fu, X.

    2009-10-01

    Application of liquid nitrogen to cooling is widely employed in many fields, such as cooling of the high temperature superconducting devices, cryosurgery and so on, in which liquid nitrogen is generally forced to flow inside very small passages to maintain good thermal performance and stability. In order to have a full understanding of the flow and heat transfer characteristics of liquid nitrogen in micro-tube, high-speed digital photography was employed to acquire the typical two-phase flow patterns of liquid nitrogen in vertically upward micro-tubes of 0.531 and 1.042 mm inner diameters. It was found from the experimental results that the flow patterns were mainly bubbly flow, slug flow, churn flow and annular flow. And the confined bubble flow, mist flow, bubble condensation and flow oscillation were also observed. These flow patterns were characterized in different types of flow regime maps. The surface tension force and the size of the diameter were revealed to be the major factors affecting the flow pattern transitions. It was found that the transition boundaries of the slug/churn flow and churn/annular flow of the present experiment shifted to lower superficial vapor velocity; while the transition boundary of the bubbly/slug flow shifted to higher superficial vapor velocity compared to the results of the room-temperature fluids in the tubes with the similar hydraulic diameters. The corresponding transition boundaries moved to lower superficial velocity when reducing the inner diameter of the micro-tubes. Time-averaged void fraction and heat transfer characteristics for individual flow patterns were presented and special attention was paid to the effect of the diameter on the variation of void fraction.

  19. Oxygen reduction reaction properties of nitrogen-incorporated nanographenes synthesized using in-liquid plasma from mixture of ethanol and iron phthalocyanine

    Science.gov (United States)

    Amano, Tomoki; Kondo, Hiroki; Takeda, Keigo; Ishikawa, Kenji; Hiramatsu, Mineo; Sekine, Makoto; Hori, Masaru

    2018-04-01

    Nanographenes were synthesized using in-liquid plasma from a mixture of iron phthalocyanine and ethanol. In a previous study, micrometer-scale flakes with nitrogen incorporation were obtained. A nonprecious metal catalytic activity was observed with 3.13 electrons in an oxygen reduction reaction under an acidic solute condition. Large-surface-area, high-graphene-crystallinity, and iron-carbon-bonding sites were found owing to a high catalytic activity in Fe-N/nanographene.

  20. Degradation mechanisms of 4-chlorophenol in a novel gas-liquid hybrid discharge reactor by pulsed high voltage system with oxygen or nitrogen bubbling.

    Science.gov (United States)

    Zhang, Yi; Zhou, Minghua; Hao, Xiaolong; Lei, Lecheng

    2007-03-01

    The effect of gas bubbling on the removal efficiency of 4-chlorophenol (4-CP) in aqueous solution has been investigated using a novel pulsed high voltage gas-liquid hybrid discharge reactor, which generates gas-phase discharge above the water surface simultaneously with the spark discharge directly in the liquid. The time for 100% of 4-CP degradation in the case of oxygen bubbling (7 min) was much shorter than that in the case of nitrogen bubbling (25 min) as plenty of hydrogen peroxide and ozone formed in oxygen atmosphere enhanced the removal efficiency of 4-CP. Except for the main similar intermediates (4-chlorocatechol, hydroquinone and 1,4-benzoquinone) produced in the both cases of oxygen and nitrogen bubbling, special intermediates (5-chloro-3-nitropyrocatechol, 4-chloro-2-nitrophenol, nitrate and nitrite ions) were produced in nitrogen atmosphere. The reaction pathway of 4-CP in the case of oxygen bubbling was oxygen/ozone attack on the radical hydroxylated derivatives of 4-CP. However, in the case of nitrogen bubbling, hydroxylation was the main reaction pathway with effect of N atom on degradation of 4-CP.

  1. Oligomerization of ethylene catalysed by nickel complexes associated with nitrogen ligands in ionic liquids; Oligomerisation de l'ethylene catalysee par des complexes du nickel associes a des ligands azotes dans les liquides ioniques

    Energy Technology Data Exchange (ETDEWEB)

    Lecocq, V.

    2003-09-01

    We report here the use of a new class of catalytic systems based on a nickel active center associated with nitrogen ligands, such as di-imines, or imino-pyridines, for the oligomerization of ethylene in a biphasic medium using ionic liquids as the catalyst solvent. The nickel catalyst is immobilized in the ionic liquid phase in which the olefinic reaction products are poorly miscible. This biphasic system makes possible an easy separation and recycle of the catalyst. Numerous di-imine and imino-pyridine ligands with different steric and electronic properties have been synthesized and their corresponding nickel complexes isolated and characterized. Different ionic liquids, based on chloro-aluminates or non-chloro-aluminates anions, have also been prepared and characterized. The effect of the nature of the ligand, the ionic liquid, the nickel precursor and its mode of activation have been studied and correlated with the selectivity and activity of the transformation of ethylene. (author)

  2. Breakup Behavior of Molten Wood's Metal Jet in Subcooled Water

    Energy Technology Data Exchange (ETDEWEB)

    Heo, Hyo; Park, Seong Dae; Bang, In Cheol [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of); Jerng, Dong Wook [Chung-Ang Univ., Seoul (Korea, Republic of)

    2014-10-15

    There are safety characteristics of the metal fueled sodium fast-cooled reactor (SFR), by identifying the possibility of early termination of severe accidents. If the molten fuel is ejected from the cladding, the ejected molten fuel can interact with the coolant in the reactor vessel. This phenomenon is called as fuel-coolant interaction (FCI). The FCI occurs at the initial phase leading to severe accidents like core disruptive accident (CDA) in the SFR. A part of the corium energy is intensively transferred to the coolant in a very short time during the FCI. The coolant vaporizes at high pressure and expands so results in steam explosion that can threat to the integrity of nuclear reactor. The intensity of steam explosion is determined by jet breakup and the fragmentation behavior. Therefore, it is necessary to understand the jet breakup between the molten fuel jet and the coolant in order to evaluate whether the steam explosion occurs or not. The liquid jet breakup has been studied in various areas, such as aerosols, spray and combustion. In early studies, small diameter jets of low density liquids were studied. The jet breakup for large density liquids has been studied in nuclear reactor field with respect to safety. The existence of vapor film layer between the melt and liquid fluid is only in case of large density breakup. This paper deals with the jet breakup experiment in non-boiling conditions in order to analyze hydraulic effect on the jet behavior. In the present study, the wood's metal was used as the jet material. It has similar properties to the metal fuel. The physical properties of molten materials and coolants are listed in Table I, respectively. It is easy to conduct the experiment due to low melting point of the wood's metal. In order to clarify the dominant factors determining jet breakup and size distribution of the debris, the experiment that the molten wood's metal was injected into the subcooled condition was conducted. The

  3. Measurement of the energy spectrum with proportional counters with spherical cathodes between 20 keV and 2.5 MeV with the propagation of 14 MeV neutrons in liquid nitrogen and liquid air

    International Nuclear Information System (INIS)

    Schneider-Kuehnle, P.

    1974-01-01

    This work deals with the measurement of the energy spectrum of a 14 MeV neutron source in liquid nitrogen and liquid air in the energy region of 20 keV to 2.5 MeV as a function of the distance from the source. The measured results together with those of a scintispectrometer which measures the energies between 2.5 MeV and 14 MeV, are to serve as experimentally-supported input data for shielding calculations and are to enable the checking of transport theoretical calculations. (orig./LH) [de

  4. An Experimental investigation of critical flow rates of subcooled water through short pipes with small diameters

    International Nuclear Information System (INIS)

    Park, Choon Kyung

    1997-02-01

    The primary objective of this study is to improve our understanding on critical flow phenomena in a small size leak and to develop a model which can be used to estimate the critical mass flow rates through reactor vessel or primary coolant pipe wall. For this purpose, critical two-phase flow phenomena of subcooled water through short pipes (100 ≤ L ≤ 400 mm) with small diameters (3.4 ≤ D ≤ 7.15 mm) have been experimentally investigated for wide ranges of subcooling (0∼199 .deg. C) and pressure (0.5∼2.0MPa). To examine the effects of various parameters (i.e., the location of flashing inception, the degree of subcooling, the stagnation temperature and pressure, and the pipe size) on the critical two-phase flow rates of subcooled water, a total of 135 runs were made for various combinations of test parameters using four different L/D test sections. Experimental results that show effects of various parameters on subcooled critical two-phase flow rates are presented. The measured static pressure profiles along the discharge pipe show that the critical flow rate can be strongly influenced by the flashing location. The locations of saturation pressure for different values of the stagnation subcooling have been consistently determined from the pressure profiles. Based upon the test results, two important parameters have been identified. These are cold state discharge coefficient and dimensionless subcooling, which are found to efficiently take into account the test section geometry and the stagnation conditions, respectively. A semi-empirical model has been developed to predict subcooled two-phase flow rates through small size openings. This model provides a simple and direct calculation of the critical mass flow rates with information on the initial condition and on the test section geometry. Comparisons between the mass fluxes calculated by present model and a total of 755 selected experimental data from 9 different investigators show that the agreement is

  5. Quantification of nitrogen in the liquid fraction and in vitro assessment of lysine bioavailability in the solid fraction of soybean meal hydrolysates.

    Science.gov (United States)

    Luján-Rhenals, D; Morawicki, R; Shi, Z; Ricke, S C

    2018-01-02

    Soybean meal (SBM) is a product generated from the manufacture of soybean oil and has the potential for use as a source of fermentable sugars for ethanol production or as a protein source for animal feeds. Knowing the levels of nitrogen available from ammonium is a necessary element of the ethanolic fermentation process while identifying the levels of essential amino acids such as lysine is important in determining usage as a feed source. As such the purpose of this study was to quantify total nitrogen and ammonium in the liquid fraction of hydrolyzed SBM and to evaluate total and bioavailable lysine in the solid fraction of the hydrolyzed SBM. The effects of acid concentration, cellulase and β-glucosidase on total and ammonium nitrogen were studied with analysis indicating that higher acid concentrations increased nitrogen compounds with ammonium concentrations ranging from 0.20 to 1.24 g L -1 while enzymatic treatments did not significantly increase nitrogen levels. Total and bioavailable lysine was quantified by use of an auxotrophic gfpmut3 E.coli whole-cell bioassay organism incapable of lysine biosynthesis. Acid and enzymatic treatments were applied with lysine bioavailability increasing from a base of 82% for untreated SBM to up to 97%. Our results demonstrated that SBM has the potential to serve in ethanolic fermentation and as an optimal source essential amino acid lysine.

  6. Assessment of CHF characteristics at subcooled conditions for the CANDU CANFLEX bundle

    International Nuclear Information System (INIS)

    Onder, E.N.; Leung, L.K.H.

    2011-01-01

    An analysis has been performed to assess the Critical Heat Flux (CHF) characteristics for the CANFLEX bundle at subcooled conditions. CHF characteristics for CANDU bundles have been established from experiments using full-scale bundle simulators. These experiments covered flow conditions of interest to normal operation and postulated loss-of-flow and small break loss-of-coolant accidents. Experimental CHF values obtained from these experiments were applied to develop correlations for analyses of regional overpower protection and safety trips. These correlations are applicable to the saturated region in the reference uncrept channel and the slightly subcooled region in postulated high-creep channels. Expanding the CHF data to subcooled conditions facilitates the evaluation of the margin to dryout at upstream bundle locations, even though dryout occurrences are not anticipated there. In view of the lack of experimental data, the ASSERT-PV subchannel code has been applied to establish CHF values at low qualities and high subcoolings (thermodynamic qualities corresponding to -25%). These CHF values have been applied to extend the CHF correlation to the highly subcooled conditions. (author)

  7. Fundamental studies on the switching in liquid nitrogen environment using vacuum switches for application in future high-temperature superconducting medium-voltage power grids

    International Nuclear Information System (INIS)

    Golde, Karsten

    2016-01-01

    By means of superconducting equipment it is possible to reduce the transmission losses in distribution networks while increasing the transmission capacity. As a result even saving a superimposed voltage level would be possible, which can put higher investment costs compared to conventional equipment into perspective. For operation of superconducting systems it is necessary to integrate all equipment in the cooling circuit. This also includes switchgears. Due to cooling with liquid nitrogen, however, only vacuum switching technology comes into question. Thus, the suitability of vacuum switches is investigated in this work. For this purpose the mechanics of the interrupters is considered first. Material investigations and switching experiments at ambient temperature and in liquid nitrogen supply information on potential issues. For this purpose, a special pneumatic construction is designed, which allows tens of thousands of switching cycles. Furthermore, the electrical resistance of the interrupters is considered. Since the contact system consists almost exclusively of copper, a remaining residual resistance and appropriate thermal losses must be considered. Since they have to be cooled back, an appropriate evaluation is given taking environmental parameters into account. The dielectric strength of vacuum interrupters is considered both at ambient temperature as well as directly in liquid nitrogen. For this purpose different contact distances are set at different interrupter types. A distinction is made between internal and external dielectric strength. Conditioning and deconditioning effects are minimized by an appropriate choice of the test circuit. The current chopping and resulting overvoltages are considered to be one of the few drawbacks of vacuum switching technology. Using a practical test circuit the height of chopping current is determined and compared for different temperatures. Due to strong scattering the evaluation is done using statistical methods. At

  8. Fertilizer performance of liquid fraction of digestate as synthetic nitrogen substitute in silage maize cultivation for three consecutive years.

    Science.gov (United States)

    Sigurnjak, I; Vaneeckhaute, C; Michels, E; Ryckaert, B; Ghekiere, G; Tack, F M G; Meers, E

    2017-12-01

    Following changes over recent years in fertilizer legislative framework throughout Europe, phosphorus (P) is taking over the role of being the limiting factor in fertilizer application rate of animal manure. This results in less placement area for spreading animal manure. As a consequence, more expensive and energy demanding synthetic fertilizers are required to meet crop nutrient requirements despite existing manure surpluses. Anaerobic digestion followed by mechanical separation of raw digestate, results in liquid fraction (LF) of digestate, a product poor in P but rich in nitrogen (N) and potassium (K). A 3-year field experiment was conducted to evaluate the impact of using the LF of digestate as a (partial) substitute for synthetic N fertilizer. Two different fertilization strategies, the LF of digestate in combination with respectively animal manure and digestate, were compared to the conventional fertilization regime of raw animal manure with synthetic fertilizers. Results from the 3-year trial indicate that the LF of digestate may substitute synthetic N fertilizers without crop yield losses. Through fertilizer use efficiency assessment it was observed that under-fertilization of soils with a high P status could reduce P availability and consequently the potential for P leaching. Under conditions of lower K application, more sodium was taken up by the crop. In arid regions, this effect might reduce the potential risk of salt accumulation that is associated with organic fertilizer application. Finally, economic and ecological benefits were found to be higher when LF of digestate was used as a synthetic N substitute. Future perspectives indicate that nutrient variability in bio-based fertilizers will be one of the greatest challenges to address in the future utilization of these products. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. [Development of a liquid fermentation system and encystment for a nitrogen-fixing bacterium strain having biofertilizer potential].

    Science.gov (United States)

    Camelo-Rusinque, Mauricio; Moreno-Galván, Andrés; Romero-Perdomo, Felipe; Bonilla-Buitrago, Ruth

    The indiscriminate use of chemical fertilizers has contributed to the deterioration of the biological, physical and chemical properties of the soil, resulting in the loss of its productive capacity. For this reason, the use of biofertilizers has emerged as a technological alternative. The objective of this research was to develop a suitable liquid fermentation system and encystment for the multiplication of Azotobacter chroococcum AC1 strain, a bacterium employed in a biofertilizer formulation produced at present by CARPOICA, Colombia. Sequential statistical designs were used to determine the conditions in the fermentation system. The interaction between agitation, aeration and pH was evaluated on the viable biomass (CFU/ml) of AC1. In addition, the encystment ability of the strain was evaluated using two encystment agents and the potential plant growth-promoting rhizobacteria (PGPR) activity was assessed by different techniques, such as nitrogen fixation by ARA, phosphate solubilization by the phospho-molybdenum-blue reaction and indolic compound production by colorimetric reaction using the Salkowski reagent. Results showed significant effects (p<0.05) on the viable biomass in the three conditions (pH, aeration and agitation) tested individually, in one dual interaction and one tripartite interaction, were demonstrated to have a positive effect on the response variable aeration and agitation. The addition of the two encystment agents evaluated, AE01 and AE02, demonstrated the ability of AC1 to form cysts under stress conditions. Likewise, fermentation and encystment conditions did not affect the biological activities tested. Copyright © 2017 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.

  10. Automated high-speed video analysis of the bubble dynamics in subcooled flow boiling

    Energy Technology Data Exchange (ETDEWEB)

    Maurus, Reinhold; Ilchenko, Volodymyr; Sattelmayer, Thomas [Technische Univ. Muenchen, Lehrstuhl fuer Thermodynamik, Garching (Germany)

    2004-04-01

    Subcooled flow boiling is a commonly applied technique for achieving efficient heat transfer. In the study, an experimental investigation in the nucleate boiling regime was performed for water circulating in a closed loop at atmospheric pressure. The test-section consists of a rectangular channel with a one side heated copper strip and a very good optical access. For the optical observation of the bubble behaviour the high-speed cinematography is used. Automated image processing and analysis algorithms developed by the authors were applied for a wide range of mass flow rates and heat fluxes in order to extract characteristic length and time scales of the bubbly layer during the boiling process. Using this methodology, a huge number of bubble cycles could be analysed. The structure of the developed algorithms for the detection of the bubble diameter, the bubble lifetime, the lifetime after the detachment process and the waiting time between two bubble cycles is described. Subsequently, the results from using these automated procedures are presented. A remarkable novelty is the presentation of all results as distribution functions. This is of physical importance because the commonly applied spatial and temporal averaging leads to a loss of information and, moreover, to an unjustified deterministic view of the boiling process, which exhibits in reality a very wide spread of bubble sizes and characteristic times. The results show that the mass flux dominates the temporal bubble behaviour. An increase of the liquid mass flux reveals a strong decrease of the bubble life - and waiting time. In contrast, the variation of the heat flux has a much smaller impact. It is shown in addition that the investigation of the bubble history using automated algorithms delivers novel information with respect to the bubble lift-off probability. (Author)

  11. Automated high-speed video analysis of the bubble dynamics in subcooled flow boiling

    International Nuclear Information System (INIS)

    Maurus, Reinhold; Ilchenko, Volodymyr; Sattelmayer, Thomas

    2004-01-01

    Subcooled flow boiling is a commonly applied technique for achieving efficient heat transfer. In the study, an experimental investigation in the nucleate boiling regime was performed for water circulating in a closed loop at atmospheric pressure. The test-section consists of a rectangular channel with a one side heated copper strip and a very good optical access. For the optical observation of the bubble behaviour the high-speed cinematography is used. Automated image processing and analysis algorithms developed by the authors were applied for a wide range of mass flow rates and heat fluxes in order to extract characteristic length and time scales of the bubbly layer during the boiling process. Using this methodology, a huge number of bubble cycles could be analysed. The structure of the developed algorithms for the detection of the bubble diameter, the bubble lifetime, the lifetime after the detachment process and the waiting time between two bubble cycles is described. Subsequently, the results from using these automated procedures are presented. A remarkable novelty is the presentation of all results as distribution functions. This is of physical importance because the commonly applied spatial and temporal averaging leads to a loss of information and, moreover, to an unjustified deterministic view of the boiling process, which exhibits in reality a very wide spread of bubble sizes and characteristic times. The results show that the mass flux dominates the temporal bubble behaviour. An increase of the liquid mass flux reveals a strong decrease of the bubble life- and waiting time. In contrast, the variation of the heat flux has a much smaller impact. It is shown in addition that the investigation of the bubble history using automated algorithms delivers novel information with respect to the bubble lift-off probability

  12. A study of vapor bubble departure in subcooled flow boiling at low pressure

    International Nuclear Information System (INIS)

    Donevski, Bozin; Saga, Tetsuo; Kobayashi, Toshio; Segawa, Shigeki

    1999-01-01

    An experimental study of vapor bubble dynamics in sub-cooled flow boiling was conducted using the flow visualization and digital image processing methods. Vapor bubble departure departure in subcooled flow boiling have been experimentally investigated over a range of mass flux G=0.384 (kg/m 2 s), and heat flux q w = 27.2 x 10 4 (W/m 2 ), for the subcooled flow boiling region. It has been observed that once a vapor bubble departs from a nucleation site, it typically slides along the heating surface at sonic finite distance down-stream of nucleation site. The image processing method proposed in this study is based on the detachment and tracing of the edges of the bubbles and their background. The proposed method can be used in various fields of engineering applications. (Original)

  13. An improved mechanistic critical heat flux model for subcooled flow boiling

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-12-31

    Based on the bubble coalescence adjacent to the heated wall as a flow structure for CHF condition, Chang and Lee developed a mechanistic critical heat flux (CHF) model for subcooled flow boiling. In this paper, improvements of Chang-Lee model are implemented with more solid theoretical bases for subcooled and low-quality flow boiling in tubes. Nedderman-Shearer`s equations for the skin friction factor and universal velocity profile models are employed. Slip effect of movable bubbly layer is implemented to improve the predictability of low mass flow. Also, mechanistic subcooled flow boiling model is used to predict the flow quality and void fraction. The performance of the present model is verified using the KAIST CHF database of water in uniformly heated tubes. It is found that the present model can give a satisfactory agreement with experimental data within less than 9% RMS error. 9 refs., 5 figs. (Author)

  14. An improved mechanistic critical heat flux model for subcooled flow boiling

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-12-31

    Based on the bubble coalescence adjacent to the heated wall as a flow structure for CHF condition, Chang and Lee developed a mechanistic critical heat flux (CHF) model for subcooled flow boiling. In this paper, improvements of Chang-Lee model are implemented with more solid theoretical bases for subcooled and low-quality flow boiling in tubes. Nedderman-Shearer`s equations for the skin friction factor and universal velocity profile models are employed. Slip effect of movable bubbly layer is implemented to improve the predictability of low mass flow. Also, mechanistic subcooled flow boiling model is used to predict the flow quality and void fraction. The performance of the present model is verified using the KAIST CHF database of water in uniformly heated tubes. It is found that the present model can give a satisfactory agreement with experimental data within less than 9% RMS error. 9 refs., 5 figs. (Author)

  15. [Enhanced nitrogen and phosphorus removal of wastewater by using sludge anaerobic fermentation liquid as carbon source in a pilot-scale system].

    Science.gov (United States)

    Luo, Zhe; Zhou, Guang-Jie; Liu, Hong-Bo; Nie, Xin-Yu; Chen, Yu; Zhai, Li-Qin; Liu, He

    2015-03-01

    In order to explore the possibility of enhanced nitrogen and phosphorus removal in wastewater using sludge anaerobic fermentation liquid as external carbon source, the present study proposed an A2/O reactor system with a total effective volume of 4 660 L and real municipal wastewater for treatment. The results showed that under the conditions of the influent COD at 243.7 mg x L(-1), NH4(+) -N at 30. 9 mg x L(-1), TN at 42.9 mg'L- , TP at 2.8 mg x L(-1), the backflow ratio of nitrification liquid at 200% and recycle ratio of sludge at 100%, the addition of acetic acid into anoxic tank could enhance the removal efficiency of nitrogen and phosphorus, and the optimal influent quantity and SCOD incremental of carbon were 7 500 L x d(-1) and 50 mg L(-1), respectively. When the sludge fermentation liquid was used as external carbon source and the average effluent COD, NH4(+) -N, TN, TP removal efficiency were 81.60%, 88.91%, 64.86% and 87.61%, the effluent concentrations were 42.18, 2.77, 11.92 and 0.19 mg x L(-1), respectively, which met China's first Class (A) criteria specified in the Discharge Standard Urban Sewage Treatment Plant Pollutant (GB 18918-2002). The results of the present study demonstrated that the addition of sludge anaerobic fermented liquid as external carbon source was a feasible way to enhance the removal of nitrogen and phosphorous in municipal wastewater, providing a new feasible strategy for the reuse and recycle of sewage sludge in China.

  16. Catalytic upgrading nitrogen-riched wood syngas to liquid hydrocarbon mixture over Fe-Pd/ZSM-5 catalyst

    Science.gov (United States)

    Qiangu Yan; Fei Yu; Zhiyong Cai; Jilei Zhang

    2012-01-01

    Biomass like wood chips, switchgrass and other plant residues are first converted to syngas through gasification process using air, oxygen or steam. A downdraft gasifier is performed for syngas production in Mississippi State. The syngas from the gasifier contains up to 49% (vol) N2. High-level nitrogen-containing (nitrogen can be up to 60%)...

  17. Experimental investigation on subcooled boiling heat transfer in a vertical double-face heated narrow annulus

    International Nuclear Information System (INIS)

    Yan Mingyu; Qiu Suizheng; Jia Dounan

    2005-01-01

    Experimental investigation on the subcooled boiling heat transfer was carried out in a vertical up-flow double narrow annulus with 1.5 mm gap. The working fluid is deionized water. The ranges of parameters as follows: pressure 0.84-6.09 MPa, mass flux 41.9-300.2 kg/(m 2 ·s), heat flux 2.61-114.41kW/m 2 . An empiric correlation used to predict the heat transfer of subcooled boiling in narrow annulus is induced from the experimental data. (author)

  18. Improvement of the RELAP5 subcooled boiling model for low pressure conditions

    International Nuclear Information System (INIS)

    Koncar, B.; Mavko, B.

    2000-01-01

    The RELAP5/MOD3.2.2 Gamma code was assessed against low pressure subcooled boiling experiments performed by Zeitoun and Shoukri [1] in a vertical annulus. The predictions of subcooled boiling bubbly flow showed that the present version of the RELAP5 code underestimates the void fraction growth along the tube. To improve the void fraction prediction at low pressure conditions a set of model changes is proposed, which includes modifications of bubbly-slug transition criterion, drift-flux model, interphase heat transfer coefficient and wall evaporation modeling. The improved experiment predictions with the modified RELAP5 code are presented and analysed. (author)

  19. Experimental study of average void fraction in low-flow subcooled boiling

    International Nuclear Information System (INIS)

    Sun Qi; Wang Xiaojun; Xi Zhao; Zhao Hua; Yang Ruichang

    2005-01-01

    Low-flow subcooled void fraction in medium pressure was investigated using high-temperature high-pressure single-sensor optical probe in this paper. And then average void fraction was obtained through the integral calculation of local void fraction in the cross-section. The experimental data were compared with the void fraction model proposed in advance. The results show that the predictions of this model agree with the data quite well. The comparisons of Saha and Levy models with low-flow subcooled data show that Saha model overestimates the experimental data distinctively, and Levy model also gets relatively higher predictions although it is better than Saha model. (author)

  20. Chaotic oscillations in a low pressure two-phase natural circulation loop under low power and high inlet subcooling conditions

    International Nuclear Information System (INIS)

    Wu, C.Y.; Wang, S.B.; Pan, C.

    1996-01-01

    The oscillation characteristics of a low pressure two-phase natural circulation loop have been investigated experimentally in this study. Experimental results indicate that the characteristics of the thermal hydraulic oscillations can be periodic, with 2-5 fundamental frequencies, or chaotic, depending on the heating power and inlet subcooling. The number of fundamental frequencies of oscillation increases if the inlet subcooling is increased at a given heating power or the heating power is decreased at a given inlet subcooling; chaotic oscillations appear if the inlet subcooling is further increased and/or the heating power is further decreased. A map of the oscillation characteristics is thus established. The change in oscillation characteristics is evident from the time evolution and power spectrum of a thermal hydraulic parameter and the phase portraits of two thermal hydraulic parameters. These results reveal that a strange attractor exists in a low pressure two-phase natural circulation loop with low power and very high inlet subcooling. (orig.)

  1. Highly Selective Separation of Carbon Dioxide from Nitrogen and Methane by Nitrile/Glycol-Difunctionalized Ionic Liquids in Supported Ionic Liquid Membranes (SILMs)

    OpenAIRE

    Hojniak, Sandra D.; Silverwood, Ian P.; Laeeq Khan, Asim; Vankelecom, Ivo F.J.; Dehaen, Wim; Kazarian, Sergei G.; Binnemans, Koen

    2014-01-01

    Novel difunctionalized ionic liquids (ILs) containing a triethylene glycol monomethyl ether chain and a nitrile group on a pyrrolidinium or imidazolium cation have been synthesized and incorporated into supported ionic liquid membranes (SILMs). These ILs exhibit ca. 2.3 times higher CO2/N2 and CO2/CH4 gas separation selectivities than analogous ILs functionalized only with a glycol chain. Although the glycol moiety ensures room temperature liquidity of the pyrrolidinium and imidazolium ILs, t...

  2. Principle of a liquid nitrogen irradiation device and its realization for use in a swimming-pool type reactor; Principe d'un dispositif d'irradiation a azote liquide et sa realisation pour utilisation dans une pile piscine

    Energy Technology Data Exchange (ETDEWEB)

    Bochirol, L; Doulat, J; Weil, L [Commissariat a l' Energie Atomique, Grenoble (France).Centre d' Etudes Nucleaires

    1961-07-01

    The problem of pile irradiation of samples immersed in liquid nitrogen has been solved with total elimination of explosion hazards and high reliability (no moving parts). The principle of the device is that of a double bath: one of high purity nitrogen cools the samples at the level of the core; a second of commercial nitrogen is located above the first one, outside the high radiation field, and works as a continuous condenser for the pure nitrogen, the flow-back of which is provided simply by gravity. The apparatus described in detail here has been designed for a swimming-pool pile. It was so designed as to provide absolute protection against radiations and to allow the irradiated samples to be easily removed in the cold condition. This apparatus has been in operation for several months. In a fast flux greater than 10{sup 13} neutrons/cm{sup 2}.s and a {gamma}-flux of the order of 10{sup 8} roentgens/h, the consumption of liquid nitrogen is of the order of 100 liters a day. (author) [French] On a resolu le probleme de l'irradiation en pile d'echantillons immerges dans l'azote liquide en construisant un appareil d'un fonctionnement sur (aucune partie n'est mobile) qui elimine completement les dangers d'explosion. Le principe de l'appareil est celui d'un double bain: l'un, d'azote pur, refroidit les echantillons au niveau du coeur du reacteur; l'autre, d'azote commercial, est situe au-dessus du premier, hors du champ de rayonnement intense, et sert de condenseur continu pour l'azote pur. Ce dernier ainsi reliquefie regagne son bain par simple gravite. L'appareil decrit en detail ici, est concu pour une pile piscine. Il a ete etudie de facon a ne creer aucune fuite de rayonnement et a permettre la recuperation aisee des echantillons irradies sans rechauffage de ceux-ci. Cet appareil est en fonctionnement depuis plusieurs mois. Dans un flux rapide superieur a 10{sup 13} neutrons/cm{sup 2}.s et un flux {gamma} de l'ordre de 10{sup 8} roentgens/h, la consommation d

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

    International Nuclear Information System (INIS)

    Briere, E.; Larrauri, D.; Olive, J.

    1995-01-01

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  5. Numerical analysis of water hammer induced by injection of subcooled water into steam flow in a horizontal pipe

    International Nuclear Information System (INIS)

    Minato, Akihiko; Nagoyoshi, Takuji; Nakamura, Akira; Fujii, Yuzo; Aya, Izuo; Yamane, Kenji

    2004-01-01

    Subcooled water injection into steam flow in piping systems may generate a water column containing a large steam slug. The steam slug collapses due to rapid condensation and interfaces on both sides collides with each other. Water hammer takes place and sharp pressure pulse propagates through the pipe. The purpose of this study is to show capability of the present numerical simulation method for predictions of pressure transient and loads on a piping system following steam slug collapse. A three-dimensional computer code for transient gas-liquid two-phase flow was applied to simulate an experiment of steam-condensation-induced water hammer with a horizontal polycarbonate pipe. The code was based on the extended two-fluid model, which treated interface motion using the VOF (Volume of Fluid) technique. The Godunov scheme of highly compressible single-phase flow was modified for application to the Riemann problem solution of gas-liquid mixture. Analysis of local steam slug collapse resulted in comparable peak pressure and pulse width of pressure transients with the observation. The calculation of pressure pulse propagation and impact load on piping system showed the quasi-steady pressure load was imposed especially on elbow at 1/10 of water hammer peak pressure. (author)

  6. Storage of Pentatomid Eggs in Liquid Nitrogen and Dormancy of Trissolcus basalis (Wollaston) and Telenomus podisi Ashmead (Hymenoptera: Platygastridae) Adults as a Method of Mass Production.

    Science.gov (United States)

    Doetzer, A K; Foerster, L A

    2013-10-01

    The eggs of pentatomid species were evaluated to parasitism by Trissolcus basalis (Wollaston) and Telenomus podisi Ashmead after storage in liquid nitrogen. Adults which emerged from stored eggs were kept at 18°C for 120 and 180 days to investigate whether adult dormancy could be associated with host egg storage in liquid nitrogen as a method of mass production of these egg parasitoids. Eggs of Nezara viridula (L.) and Acrosternum pengue (Rolston) were successfully parasitized by T. basalis, as well as Piezodorus guildinii (Westwood) and Dichelops furcatus (F.) by T. podisi. The eggs of Edessa meditabunda (F.) were not parasitized by T. basalis. The emergence of T. podisi from eggs of Euschistus heros (F.) and Podisus nigrispinus (Dallas) stored for 6 months was lower than the control. Females of T. basalis and T. podisi that emerged from stored eggs were kept in dormancy at 18°C. Longevity of T. basalis was influenced by the storage time and sex, but not by the interaction of sex and storage time. For T. podisi, longevity was influenced by the storage time, sex, and by the interaction of sex and storage time. For T. basalis, storage in liquid nitrogen did not affect the fecundity of quiescent females, while the number of parasitized eggs by T. podisi decreased after storage. By the joint use of these techniques, it is possible to optimize mass production of T. basalis so that its life cycle can be monitored and synchronized with the life cycle and availability of hosts.

  7. Long term storage in liquid nitrogen leads to only minor phenotypic and gene expression changes in the mammary carcinoma model cell line BT474.

    Science.gov (United States)

    Fazekas, Judit; Grunt, Thomas W; Jensen-Jarolim, Erika; Singer, Josef

    2017-05-23

    Cancer cell lines are indispensible surrogate models in cancer research, as they can be used off-the-shelf, expanded to the desired extent, easily modified and exchanged between research groups for affirmation, reproduction or follow-up experiments.As malignant cells are prone to genomic instability, phenotypical changes may occur after certain passages in culture. Thus, cell lines have to be regularly authenticated to ensure data quality. In between experiments these cell lines are often stored in liquid nitrogen for extended time periods.Although freezing of cells is a necessary evil, little research is performed on how long-term storage affects cancer cell lines. Therefore, this study investigated the effects of a 28-year long liquid nitrogen storage period on BT474 cells with regard to phenotypical changes, differences in cell-surface receptor expression as well as cytokine and gene expressional variations. Two batches of BT474 cells, one frozen in 1986, the other directly purchased from ATCC were investigated by light microscopy, cell growth analysis, flow cytometry and cytokine as well as whole-transcriptome expression profiling. The cell lines were morphologically indifferent and showed similar growth rates and similar cell-surface receptor expression. Transcriptome analysis revealed significant differences in only 26 of 40,716 investigated RefSeq transcripts with 4 of them being up-regulated and 22 down-regulated. This study demonstrates that even after very long periods of storage in liquid nitrogen, cancer cell lines display only minimal changes in their gene expression profiles. However, also such minor changes should be carefully assessed before continuation of experiments, especially if phenotypic alterations can be additionally observed.

  8. Nitrogen removal from sludge digester liquids by nitrification/denitrification or partial nitritation/anammox: environmental and economical considerations.

    Science.gov (United States)

    Fux, C; Siegrist, H

    2004-01-01

    In wastewater treatment plants with anaerobic sludge digestion, 15-20% of the nitrogen load is recirculated to the main stream with the return liquors from dewatering. Separate treatment of this ammonium-rich digester supernatant significantly reduces the nitrogen load of the activated sludge system. Two biological applications are considered for nitrogen elimination: (i) classical autotrophic nitrification/heterotrophic denitrification and (ii) partial nitritation/autotrophic anaerobic ammonium oxidation (anammox). With both applications 85-90% nitrogen removal can be achieved, but there are considerable differences in terms of sustainability and costs. The final gaseous products for heterotrophic denitrification are generally not measured and are assumed to be nitrogen gas (N2). However, significant nitrous oxide (N2O) production can occur at elevated nitrite concentrations in the reactor. Denitrification via nitrite instead of nitrate has been promoted in recent years in order to reduce the oxygen and the organic carbon requirements. Obviously this "achievement" turns out to be rather disadvantageous from an overall environmental point of view. On the other hand no unfavorable intermediates are emitted during anaerobic ammonium oxidation. A cost estimate for both applications demonstrates that partial nitritation/anammox is also more economical than classical nitrification/denitrification. Therefore autotrophic nitrogen elimination should be used in future to treat ammonium-rich sludge liquors.

  9. Analysis on energy saving potential of integrated supermarket HVAC and refrigeration systems using multiple subcoolers

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Liang [Institute of Refrigeration and Cryogenics, Shanghai Jiaotong University, Shanghai 200240 (China); China R and D Center, Carrier Corporation, No. 3239 Shen Jiang Road, Shanghai 201206 (China); Zhang, Chun-Lu [China R and D Center, Carrier Corporation, No. 3239 Shen Jiang Road, Shanghai 201206 (China)

    2010-02-15

    The paper presents a model-based analysis on the energy saving potential of supermarket HVAC (heating, ventilating, and air-conditioning) and refrigeration systems using multiple subcoolers among the high-temperature HVAC system, the medium-temperature refrigeration system, and the low-temperature refrigeration system. The principle of energy reduction is to have the higher COP (coefficient of performance) system generate more cooling capacity to increase the cooling capacity or reduce the power consumption of the lower COP system. The subcooler could be placed between the medium-temperature and low-temperature systems, between the high-temperature and medium-temperature systems, and between the high-temperature and low-temperature systems. All integration scenarios of adding one, two and three subcoolers have been investigated. The energy saving potential varies with the load ratio between high-, medium- and low-temperature systems, COP of three systems, and the ''on-off'' duty time of HVAC system. The optimal sequence of adding subcoolers is also proposed. (author)

  10. Exploring symbiotic nitrogen fixation and assimilation in pea root nodules by in vivo 15N nuclear magnetic resonance spectroscopy and liquid chromatography-mass spectrometry

    DEFF Research Database (Denmark)

    Scharff, A.M.; Egsgaard, H.; Hansen, P.E.

    2003-01-01

    Nitrogen (N) fixation and assimilation in pea (Pisum sativum) root nodules were studied by in vivo N-15 nuclear magnetic resonance (NMR) by exposing detached nodules to N-15, via a perfusion medium, while recording a time course of spectra. In vivo P-31 NMR spectroscopy was used to monitor...... the physiological state of the metabolically active nodules. The nodules were extracted after the NMR studies and analyzed for total soluble amino acid pools and N-15 labeling of individual amino acids by liquid chromatography-mass spectrometry. A substantial pool of free ammonium was observed by N-15 NMR...... labeling of Asn was observed by liquid chromatography-mass spectrometry, which is consistent with the generally accepted role of Asn as the end product of primary N assimilation in pea nodules. However, the Asn N-15 amino signal was absent in in vivo N-15 NMR spectra, which could be because...

  11. Phenomenology and thermo-hydraulic stability of the CAREM-25 reactor: Evaluation of subcooled boiling effect

    International Nuclear Information System (INIS)

    Acuna, F.M.; Marcel, C.P.; Zanocco, P.G.; Delmastro, D.F.

    2012-01-01

    In this article the phenomenology present in self/pressurized, integral, natural circulation, low thermodynamic quality nuclear reactors similar to CAREM-25 is investigated. In particular, analytical relations for the mass flow rate, the core mean enthalpy and the location of the two phase boundary are derived in terms of the so-called natural variables of the system: the nuclear power, the condensation power and the system pressure. In addition, some consequences of the flashing phenomenon in the reactor thermal-hydraulics are discussed emphasizing those affecting the reactor stability. The reactor stability performance was studied by using the HUARPE code which is a low diffusive code. The stability results obtained by neglecting the subcooled effect in the system are presented in the so-called the stability maps in which the results are presented for a wide range of conditions. The stability effect caused by the presence of subcooled boiling in the reactor core was also examined. In order to investigate such a consequence, the code was slightly modified such that the predicted vapor profile in the hot leg is similar to that estimated by RELAP system code at steady state conditions. The simple implemented algorithm allows varying a free parameter with which a broad number of cases can be studied. This is important since the subcooled boiling predictions generally have large uncertainties and therefore to cover a large number of situations is desired to derive confident conclusions. The results show the existence of vapor created by means of subcooled boiling enhances the system stability for a wide range of conditions. For this reason from this preliminary investigation, it is concluded neglecting the subcooled effect in CAREM-25 stability studies is a conservative criterion (author))

  12. Performance evaluation of an ejector subcooled vapor-compression refrigeration cycle

    International Nuclear Information System (INIS)

    Xing, Meibo; Yan, Gang; Yu, Jianlin

    2015-01-01

    Highlights: • An ejector subcooled vapor-compression refrigeration cycle is proposed. • The performance of the cycle with ejector subcooling is evaluated theoretically. • Increase in refrigeration capacity can be achieved by the ejector subcooled cycle. • The new cycle exhibits higher COP compared to the basic single-stage cycle. • Performance of the new cycle depends on the operation pressures of the ejector. - Abstract: In this study, a novel vapor-compression refrigeration cycle with mechanical subcooling using an ejector is proposed to improve the performance of a conventional single-stage vapor-compression refrigeration cycle. In the theoretical study, a mathematical model is developed to predict the performance of the cycle by using R404A and R290, and then compared with that of the conventional refrigeration cycle. The simulation results show that the performance of the ejector subcooled cycle is better than that of the conventional cycle. When the evaporator temperature ranges from −40 to −10 °C and the condenser temperature is 45 °C, the novel cycle displays volumetric refrigeration capacity improvements of 11.7% with R404A and 7.2% with R290. And the novel cycle achieves COP improvements of 9.5% with R404A and 7.0% with R290. In addition, the improvement of the COP and cooling capacity of this novel cycle largely depends on the operation pressures of the ejector. The potential practical advantages offered by the cycle may be worth further attention in future studies

  13. Superconducting materials at temperature higher than liquid nitrogen of the YBaCuO type. Materiaux supraconducteurs jusqu'a des temperatures superieures a celles de l'azote liquide, appartenant au systeme Y-Ba-Cu-O

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, R; Gegnier, P; Truchot, P

    1990-02-09

    The invention concerns new superconducting materials with the formula Zr{sub x} Hf{sub y} Ti{sub z} Y{sub 1-x-y-z} Ba{sub 2}Cu{sub 3}O{sub 7-{delta}} where 0liquid nitrogen and can be used as wire, solid parts, thin or thick layers.

  14. A sensitive and efficient method for trace analysis of some phenolic compounds using simultaneous derivatization and air-assisted liquid-liquid microextraction from human urine and plasma samples followed by gas chromatography-nitrogen phosphorous detection.

    Science.gov (United States)

    Farajzadeh, Mir Ali; Afshar Mogaddam, Mohammad Reza; Alizadeh Nabil, Ali Akbar

    2015-12-01

    In present study, a simultaneous derivatization and air-assisted liquid-liquid microextraction method combined with gas chromatography-nitrogen phosphorous detection has been developed for the determination of some phenolic compounds in biological samples. The analytes are derivatized and extracted simultaneously by a fast reaction with 1-flouro-2,4-dinitrobenzene under mild conditions. Under optimal conditions low limits of detection in the range of 0.05-0.34 ng mL(-1) are achievable. The obtained extraction recoveries are between 84 and 97% and the relative standard deviations are less than 7.2% for intraday (n = 6) and interday (n = 4) precisions. The proposed method was demonstrated to be a simple and efficient method for the analysis of phenols in biological samples. Copyright © 2015 John Wiley & Sons, Ltd.

  15. THE LIQUID NITROGEN SYSTEM FOR CHAMBER A; A CHANGE FROM ORIGINAL FORCED FLOW DESIGN TO A NATURAL FLOW (THERMO SIPHON) SYSTEM

    International Nuclear Information System (INIS)

    Homan, J.; Montz, M.; Ganni, V.; Sidi-Yekhlef, A.; Knudsen, P.; Creel, J.; Arenius, D.; Garcia, S.

    2010-01-01

    NASA at the Johnson Space Center (JSC) in Houston is presently working toward modifying the original forced flow liquid nitrogen cooling system for the thermal shield in the space simulation chamber-A in Building 32 to work as a natural flow (thermo siphon) system. Chamber A is 19.8 m (65 ft) in diameter and 35.66 m (117 ft) high. The LN 2 shroud environment within the chamber is approximately 17.4 m (57 ft) in diameter and 28 m (92 ft) high. The new thermo siphon system will improve the reliability, stability of the system. Also it will reduce the operating temperature and the liquid nitrogen use to operate the system. This paper will present the requirements for the various operating modes. System level thermodynamic comparisons of the existing system to the various options studied and the final option selected will be outlined. A thermal and hydraulic analysis to validate the selected option for the conversion of the current forced flow to natural flow design will be discussed. The proposed modifications to existing system to convert to natural circulation (thermo siphon) system and the design features to help improve the operations, and maintenance of the system will be presented.

  16. Numerical study of the underexpanded nitrogen jets submerged into liquid sodium in the frame of Sodium-cooled Fast Reactor (SFRs)

    International Nuclear Information System (INIS)

    Chen, F.; Allou, A.; Parisse, J.D.

    2017-01-01

    The study of the consequences of a gas leakage in the secondary/ tertiary heat exchangers is one of the essential points in the safety analysis of Sodium-cooled Fast nuclear Reactors (SFRs). This work is in the frame of the technology of the Compact plates Sodium-Gas heat Exchangers (ECSG) which is an alternative to conventional steam Rankine cycles. The overpressure of the tertiary nitrogen loop causes the formation of underexpanded gas jets submerged in the liquid sodium. In order to establish a safety evaluation, it would be an asset to be able to estimate the leakage. The gas leak detection by the acoustic method based on the bubbles field has been proposed. It requires then a delicate knowledge of the bubble field. This work contributes to development a numerical tool and its validation to model the transport and the production of bubbles in the downstream of underexpanded gas jets. The code CANOP modeling bi-phasic compressible flow is investigated under the actual condition of the underexpanded nitrogen jets submerged in the liquid sodium in an ECSG channel. Expensive computational cost is limited by using an Adaptive Mesh Refinement. (author)

  17. Modernization of NASA's Johnson Space Center Chamber: A Liquid Nitrogen System to Support Cryogenic Vacuum Optical Testing of the James Webb Space Telescope (JWST)

    Science.gov (United States)

    Garcia, Sammy; Homan, Jonathan; Montz, Michael

    2016-01-01

    NASA is the mission lead for the James Webb Space Telescope (JWST), the next of the “Great Observatories”, scheduled for launch in 2018. It is directly responsible for the integration and test (I&T) program that will culminate in an end-to-end cryo vacuum optical test of the flight telescope and instrument module in Chamber A at NASA Johnson Space Center. Historic Chamber A is the largest thermal vacuum chamber at Johnson Space Center and one of the largest space simulation chambers in the world. Chamber A has undergone a major modernization effort to support the deep cryogenic, vacuum and cleanliness requirements for testing the JWST. This paper describes the steps performed in efforts to convert the existing the 60’s era Liquid Nitrogen System from a forced flow (pumped) process to a natural circulation (thermo-siphon) process. In addition, the paper will describe the dramatic conservation of liquid nitrogen to support the long duration thermal vacuum testing. Lastly, describe the simplistic and effective control system which results in zero to minimal human inputs during steady state conditions.

  18. Preparation of a liquid nitrogen target for measurement of γ-ray in the 14N(n,γ)15N reaction as an intensity standard in energy region up to 11 MeV

    International Nuclear Information System (INIS)

    Hirano, M.; Obayashi, H.; Sakane, H.; Shibata, M.; Kawade, K.; Taniguchi, A.

    2001-01-01

    For determination of relative γ-ray intensities up to 11 MeV in the 14 N(n,γ) 15 N reaction, we have developed a liquid nitrogen (N 2 ) target which contain no hydrogen (H) to improve the accuracy of γ-ray intensities. The ratio of the relative uncertainties for the liquid nitrogen to that for the melamine (C 3 H 6 N 6 ) widely used was improved by a factor of 2 above 2.2 MeV and a factor of 3 - 6 below 2.2 MeV. It has been shown that the liquid nitrogen target is useful for reduction of the 2.2 MeV γ-ray from the 1 H(n,γ) 2 H reaction and improvement of statistics. (author)

  19. Effects of solid-liquid separation on recovering residual methane and nitrogen from digested dairy cow manure

    DEFF Research Database (Denmark)

    Kaparaju, Prasad Laxmi-Narasimha; Rintala, J.A.

    2008-01-01

    The feasibility of optimizing methane and nitrogen recovery of samples obtained from farm biogas digester (35 degrees C) and post-storage tank (where digested material is stored for 9-12 months) was studied by separating the materials into different fractions using 2, 1, 0.5 and 0.25 mm sieves...

  20. Wipe selection for the analysis of surface materials containing chemical warfare agent nitrogen mustard degradation products by ultra-high pressure liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Willison, Stuart A

    2012-12-28

    Degradation products arising from nitrogen mustard chemical warfare agent were deposited on common urban surfaces and determined via surface wiping, wipe extraction, and liquid chromatography–tandem mass spectrometry detection. Wipes investigated included cotton gauze, glass fiber filter, non-woven polyester fiber and filter paper, and surfaces included several porous (vinyl tile, painted drywall, wood) and mostly non-porous (laminate, galvanized steel, glass) surfaces. Wipe extracts were analyzed by ultra-high pressure liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) and compared with high performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS) results. An evaluation of both techniques suggests UPLC–MS/MS provides a quick and sensitive analysis of targeted degradation products in addition to being nearly four times faster than a single HPLC run, allowing for greater throughput during a wide-spread release concerning large-scale contamination and subsequent remediation events. Based on the overall performance of all tested wipes, filter paper wipes were selected over other wipes because they did not contain interferences or native species (TEA and DEA) associated with the target analytes, resulting in high percent recoveries and low background levels during sample analysis. Other wipes, including cotton gauze, would require a pre-cleaning step due to the presence of large quantities of native species or interferences of the targeted analytes. Percent recoveries obtained from a laminate surface were 47–99% for all nitrogen mustard degradation products. The resulting detection limits achieved from wipes were 0.2 ng/cm(2) for triethanolamine (TEA), 0.03 ng/cm(2) for N-ethyldiethanolamine (EDEA), 0.1 ng/cm(2) for N-methyldiethanolamine (MDEA), and 0.1 ng/cm(2) for diethanolamine (DEA).

  1. GreenChill Store Certification Protocol for Sub-Cooling Contained on Racks Separate from Refrigeration Equipment

    Science.gov (United States)

    Document describes the protocol used to determine the total load and refrigerant charge of stores that have placed all sub-cooling on a rack separate from all other commercial refrigeration equipment.

  2. First signal from a broadband cryogenic preamplifier cooled by circulating liquid nitrogen in a 7 T Fourier transform ion cyclotron resonance mass spectrometer.

    Science.gov (United States)

    Choi, Myoung Choul; Lee, Jeong Min; Lee, Se Gyu; Choi, Sang Hwan; Choi, Yeon Suk; Lee, Kyung Jae; Kim, SeungYong; Kim, Hyun Sik; Stahl, Stefan

    2012-12-18

    Despite the outstanding performance of Fourier transform ion cyclotron/mass spectrometry (FTICR/MS), the complexity of the cellular proteome or natural compounds presents considerable challenges. Sensitivity is a key performance parameter of a FTICR mass spectrometer. By improving this parameter, the dynamic range of the instrument can be increased to improve the detection signal of low-abundance compounds or fragment ion peaks. In order to improve sensitivity, a cryogenic detection system was developed by the KBSI (Korean Basic Science Institute) in collaboration with Stahl-Electronics (Mettenheim, Germany). A simple, efficient liquid circulation cooling system was designed and a cryogenic preamplifier implemented inside a FTICR mass spectrometer. This cooling system circulates a cryoliquid from a Dewar to the "liquid circulation unit" through a CF flange to cool a copper block and a cryopreamplifier; the cooling medium is subsequently exhausted into the air. The cryopreamplifier can be operated over a very wide temperature range, from room temperature to low temperature environments (4.2 K). First, ion signals detected by the cryopreamplifier using a circulating liquid nitrogen cooling system were observed and showed a signal-to-noise ratio (S/N) about 130% better than that obtained at room temperature.

  3. Status of GENIUS-TF-II and TF-III-The long-term stability of naked detectors in liquid nitrogen

    Energy Technology Data Exchange (ETDEWEB)

    Klapdor-Kleingrothaus, H.V. [Max-Planck-Institut fuer Kernphysik, P.O. Box 10 39 80, D-69029 Heidelberg (Germany)]. E-mail: H.Klapdor@mpi-hd.mpg.de; Krivosheina, I.V. [Max-Planck-Institut fuer Kernphysik, P.O. Box 10 39 80, D-69029 Heidelberg (Germany)

    2006-10-15

    GENIUS-TF-II is a setup of six naked high purity Ge detectors (15kg) in liquid nitrogen in Gran Sasso. It has been installed in October, 2004-after the first four naked Ge detectors had been installed on May 5, 2003 (GENIUS-TF-I). The GENIUS-Test-Facility (GENIUS-TF) is the first and up to now only setup ever testing the novel technique aiming at extreme background reduction in search for rare decays in particular underground. The goal of GENIUS-TF was to test some key operational parameters of the full GENIUS project proposal in 1997 [H.V. Klapdor-Kleingrothaus, Int. J. Mod. Phys. A 13 (1998) 3953; H.V. Klapdor-Kleingrothaus, J. Hellmig, M. Hirsch, GENIUS-Proposal, 20 November 1997; J. Hellmig and H.V. Klapdor-Kleingrothaus, Z. Phys. A 359 ( 1997) 351 and nucl-ex/9801004; H.V. Klapdor-Kleingrothaus, M. Hirsch, Z. Phys. A 359 (1997) 361; H.V. Klapdor-Kleingrothaus, J. Hellmig, M. Hirsch, J. Phys. G 24 (1998) 483; H.V. Klapdor-Kleingrothaus, CERN Courier, November 1997, pp. 16-18]. Simultaneous physical goal is to search for the annual modulation of the Dark Matter signal [H.V. Klapdor-Kleingrothaus, et al., Nucl. Instr. and Meth. A 481 (2002) 149; C. Tomei, A. Dietz, I. Krivosheina, H.V. Klapdor-Kleingrothaus, Nucl. Instr. and Meth. 508 (2003) 343]. After operation of GENIUS-TF over three years with finally six naked Ge detectors (15kg) in liquid nitrogen in Gran Sasso we realize serious problems for realization of a full-size GENIUS-like experiment: (1) Background from Rn222 diffusing into the setup, on a level far beyond the expectation. (2) Limited long-term stability of naked detectors in liquid nitrogen as result of increasing leakage current. None of the six detectors is running after three years with the nominal leakage current. Three of the six detectors do not work any more at all. The results of our three years of investigation of the long-term stability may cast doubt on the possibility to perform full GENIUS-like projects.

  4. Status of GENIUS-TF-II and TF-III-The long-term stability of naked detectors in liquid nitrogen

    International Nuclear Information System (INIS)

    Klapdor-Kleingrothaus, H.V.; Krivosheina, I.V.

    2006-01-01

    GENIUS-TF-II is a setup of six naked high purity Ge detectors (15kg) in liquid nitrogen in Gran Sasso. It has been installed in October, 2004-after the first four naked Ge detectors had been installed on May 5, 2003 (GENIUS-TF-I). The GENIUS-Test-Facility (GENIUS-TF) is the first and up to now only setup ever testing the novel technique aiming at extreme background reduction in search for rare decays in particular underground. The goal of GENIUS-TF was to test some key operational parameters of the full GENIUS project proposal in 1997 [H.V. Klapdor-Kleingrothaus, Int. J. Mod. Phys. A 13 (1998) 3953; H.V. Klapdor-Kleingrothaus, J. Hellmig, M. Hirsch, GENIUS-Proposal, 20 November 1997; J. Hellmig and H.V. Klapdor-Kleingrothaus, Z. Phys. A 359 ( 1997) 351 and nucl-ex/9801004; H.V. Klapdor-Kleingrothaus, M. Hirsch, Z. Phys. A 359 (1997) 361; H.V. Klapdor-Kleingrothaus, J. Hellmig, M. Hirsch, J. Phys. G 24 (1998) 483; H.V. Klapdor-Kleingrothaus, CERN Courier, November 1997, pp. 16-18]. Simultaneous physical goal is to search for the annual modulation of the Dark Matter signal [H.V. Klapdor-Kleingrothaus, et al., Nucl. Instr. and Meth. A 481 (2002) 149; C. Tomei, A. Dietz, I. Krivosheina, H.V. Klapdor-Kleingrothaus, Nucl. Instr. and Meth. 508 (2003) 343]. After operation of GENIUS-TF over three years with finally six naked Ge detectors (15kg) in liquid nitrogen in Gran Sasso we realize serious problems for realization of a full-size GENIUS-like experiment: (1) Background from Rn222 diffusing into the setup, on a level far beyond the expectation. (2) Limited long-term stability of naked detectors in liquid nitrogen as result of increasing leakage current. None of the six detectors is running after three years with the nominal leakage current. Three of the six detectors do not work any more at all. The results of our three years of investigation of the long-term stability may cast doubt on the possibility to perform full GENIUS-like projects

  5. Effect of Dissolved gas on bubble behavior of subcooled boiling in narrow channel

    International Nuclear Information System (INIS)

    Li Shaodan; Tan Sichao; Xu Chao; Gao Puzhen; Xu Jianjun

    2013-01-01

    An experimental investigation was performed to study the effect of dissolved gas on bubble behavior in narrow rectangular channel under subcooled boiling condition. A high-speed digital video camera was applied to capture the dynamics of the bubble with or without dissolved gas in a narrow rectangular channel. It is found that the dissolved gas has great influence on bubble behavior in subcooled boiling condition. The dissolved gas slows down the rate of bubble growth and condensation and makes the variation of the bubble diameter present some oscillation characteristics. This phenomenon was discussed in the view of the vapor evaporation and condensation. The existence of the dissolved gas can facilitate the survival of the bubble and promote the aggregation of bubbles, and enhence heat transfer enhancement in some ways. (authors)

  6. An appraisal of subcooled boiling and slip ratio from measurements made in Lingen BWR

    International Nuclear Information System (INIS)

    Nash, G.

    1977-08-01

    Measurements of steam bubble velocities and voidage have been made in the relatively small Core B of Lingen BWR. The results of axial scanning in one radial position have produced experimental values of slip ratio, power (from a travelling incore probe), voidage and coolant mean density over the core height for this position. This one set of distributions has enabled us to test current UKAEA models of subcooled boiling and slip ratio against experiment. From the comparisons, it appears that we can predict the onset of voiding well, but the assumption that a constant fraction of the heat flux forms steam in the subcooled region needs modifying. Of four slip options tested, the current one used by HAMBO and JOSHUA III (Bankoff-Jones) predicts too high a slip ratio. A closer fit to experiment comes from the new Bryce flow-dependent slip option. Any changes in the modelling must be checked, however, with coupled thermal hydraulics-neutronics computations. (author)

  7. Assessment of CHF characteristics at subcooled conditions for the CANFLEX bundle

    International Nuclear Information System (INIS)

    Onder, E.N.; Leung, L.K.H.

    2013-01-01

    Boiling-Length-Average (BLA) Critical Heat Flux (CHF) values for the CANFLEX bundle at cross-sectional average subcooled conditions have been evaluated using the ASSERT-PV subchannel code. The predicted BLA CHF values supplement experimental BLA CHF values obtained with full-scale bundle simulators at saturated conditions in developing a BLA CHF correlation applicable over the interested range of cross-sectional average thermodynamic quality in regional overpower protection (ROP) trip and safety analyses. The BLA CHF correlation exhibits similar characteristics to those observed in tubes at subcooled and saturated conditions. Applying this correlation has led to similar prediction accuracy in dryout power to that using the BLA CHF-data-based correlation at saturated conditions. However, it provides improved prediction accuracy in dryout power at dryout conditions near saturation compared to the BLA CHF-data-based correlation (which tends to underpredict the dryout power)

  8. A formal approach for the prediction of the critical heat flux in subcooled water

    Energy Technology Data Exchange (ETDEWEB)

    Lombardi, C. [Polytechnic of Milan (Italy)

    1995-09-01

    The critical heat flux (CHF) in subcooled water at high mass fluxes are not yet satisfactory correlated. For this scope a formal approach is here followed, which is based on an extension of the parameters and the correlation used for the dryout prediction for medium high quality mixtures. The obtained correlation, in spite of its simplicity and its explicit form, yields satisfactory predictions, also when applied to more conventional CHF data at low-medium mass fluxes and high pressures. Further improvements are possible, if a more complete data bank will be available. The main and general open item is the definition of a criterion, depending only on independent parameters, such as mass flux, pressure, inlet subcooling and geometry, to predict whether the heat transfer crisis will result as a DNB or a dryout phenomenon.

  9. IAEA ICSP on HWR moderator subcooling requirements to demonstrate backup heat sink

    International Nuclear Information System (INIS)

    Choi, J.; Nitheanandan, T.

    2013-01-01

    The IAEA launched a new International Collaborative Standard Problem (ICSP) on 'HWR Moderator Subcooling Requirements to Demonstrate Backup Heat Sink Capabilities of Moderator during Accidents'. The purpose of the ICSP is to benchmark analysis computer codes in simulating contact boiling experimental data to assess the subcooling requirements for an overheated pressure tube, plastically deforming into contact with the calandria tube during a postulated large break loss of coolant accident. The experimental data obtained for the ICSP blind simulation can be used to assess safety analysis computer codes simulating thermal radiation heat transfer to the pressure tube, pressure tube deformation or failure, pressure tube to calandria tube heat transfer, calandria tube to moderator heat transfer, and calandria tube deformation or failure. (author)

  10. Point of net vapor generation and vapor void fraction in subcooled boiling

    International Nuclear Information System (INIS)

    Saha, P.; Zuber, N.

    1974-01-01

    An analysis is presented directed at predicting the point of net vapor generation and vapor void fraction in subcooled boiling. It is shown that the point of net vapor generation depends upon local conditions--thermal and fluid dynamic. Thus, at low mass flow rates the net vapor generation is determined by thermal conditions, whereas at high mass flow rates the phenomenon is hydrodynamically controlled. Simple criteria are derived which can be used to predict these local conditions for net vapor generation. These criteria are used to determine the vapor void fraction is subcooled boiling. Comparison between the results predicted by this analysis and experimental data presently available shows good agreement for wide range of operating conditions, fluids and geometries. (U.S.)

  11. Determination of heat transfer coefficient for an interaction of sub-cooled gas and metal

    International Nuclear Information System (INIS)

    Sidek, Mohd Zaidi; Kamarudin, Muhammad Syahidan

    2016-01-01

    Heat transfer coefficient (HTC) for a hot metal surface and their surrounding is one of the need be defined parameter in hot forming process. This study has been conducted to determine the HTC for an interaction between sub-cooled gas sprayed on a hot metal surface. Both experiments and finite element have been adopted in this work. Initially, the designated experiment was conducted to obtain temperature history of spray cooling process. Then, an inverse method was adopted to calculate the HTC value before we validate in a finite element simulation model. The result shows that the heat transfer coefficient for interaction of subcooled gas and hot metal surface is 1000 W/m 2 K. (paper)

  12. A formal approach for the prediction of the critical heat flux in subcooled water

    International Nuclear Information System (INIS)

    Lombardi, C.

    1995-01-01

    The critical heat flux (CHF) in subcooled water at high mass fluxes are not yet satisfactory correlated. For this scope a formal approach is here followed, which is based on an extension of the parameters and the correlation used for the dryout prediction for medium high quality mixtures. The obtained correlation, in spite of its simplicity and its explicit form, yields satisfactory predictions, also when applied to more conventional CHF data at low-medium mass fluxes and high pressures. Further improvements are possible, if a more complete data bank will be available. The main and general open item is the definition of a criterion, depending only on independent parameters, such as mass flux, pressure, inlet subcooling and geometry, to predict whether the heat transfer crisis will result as a DNB or a dryout phenomenon

  13. A study on the effects of heated surface wettability on nucleation characteristics in subcooled flow boiling

    International Nuclear Information System (INIS)

    Kajihara, Tomoyuki; Kaiho, Kazuhiro; Okawa, Tomio

    2014-01-01

    Subcooled flow boiling plays an important role in boiling water reactors because it influences the heat transfer performance from fuel rods, two-phase flow stabilities, and neutron moderation characteristics. In the present study, flow visualization of water subcooled flow boiling in a vertical heated channel was carried out to investigate the mechanisms of void fraction development. The two surfaces of distinctly different contact angles were used as the heated surface to investigate the effect of the surface wettability. It was observed that with an increase in the wall heat flux, more nucleation sites were activated and larger bubbles were produced at low-frequency. It was considered that formation of these large bubbles primarily contributed to the void fraction development. (author)

  14. Sensitivity Analysis of RCW Temperature on the Moderator Subcooling Margin for the LBLOCA of Wolsong NPP Unit 1

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Si Won; Kim, Jong Hyun; Choi, Sung Soo [Atomic Creative Technology Co., Daejeon (Korea, Republic of); Kim, Sung Min [Central Research Institute, Korea Hydro and Nuclear Power Co., Daejeon (Korea, Republic of)

    2016-05-15

    Moderator subcooling margin has been analyzed using the MODTURC{sub C}LAS code in the Large LOCA FSAR PARTs C and F. Performance of moderator heat exchangers depends on RCW (Raw reCirculated Water) temperature. And also the temperature is affected by sea water temperature. Unfortunately, sea water temperature is gradually increasing by global warming. So it will cause increase of RCW temperature inevitably. There is no assessment result of moderator subcooling with increasing RCW temperature even if it is important problem. Therefore, sensitivity analysis is performed to give information about the relation between RCW temperature and moderator subcooling in the present study. The moderator subcooling margin has to be ensured to establish the moderator heat removal when Large LOCA with LOECI and Loss of Class IV Power occurs. However, sea water temperature is increasing gradually due to global warming. So it is necessary that sensitivity analysis of RCW temperature on the moderator subcooling margin to estimate the availability of the moderator heat removal. In the present paper, the moderator subcooling analysis is performed using the same methodology and assumptions except for RCW temperature used in FSAR Large LOCA PART F.

  15. Sensitivity Analysis of RCW Temperature on the Moderator Subcooling Margin for the LBLOCA of Wolsong NPP Unit 1

    International Nuclear Information System (INIS)

    Seo, Si Won; Kim, Jong Hyun; Choi, Sung Soo; Kim, Sung Min

    2016-01-01

    Moderator subcooling margin has been analyzed using the MODTURC_CLAS code in the Large LOCA FSAR PARTs C and F. Performance of moderator heat exchangers depends on RCW (Raw reCirculated Water) temperature. And also the temperature is affected by sea water temperature. Unfortunately, sea water temperature is gradually increasing by global warming. So it will cause increase of RCW temperature inevitably. There is no assessment result of moderator subcooling with increasing RCW temperature even if it is important problem. Therefore, sensitivity analysis is performed to give information about the relation between RCW temperature and moderator subcooling in the present study. The moderator subcooling margin has to be ensured to establish the moderator heat removal when Large LOCA with LOECI and Loss of Class IV Power occurs. However, sea water temperature is increasing gradually due to global warming. So it is necessary that sensitivity analysis of RCW temperature on the moderator subcooling margin to estimate the availability of the moderator heat removal. In the present paper, the moderator subcooling analysis is performed using the same methodology and assumptions except for RCW temperature used in FSAR Large LOCA PART F.

  16. Two-phase flow regimes and mechanisms of critical heat flux under subcooled flow boiling conditions

    International Nuclear Information System (INIS)

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

    2010-01-01

    A literature review of critical heat flux (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 experimental information. 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. Even though the selected concept has not received much attention (in term or theoretical developments and applications) as compared to other more popular DNB models, its basis have often been cited by experimental investigators and is considered by the authors as the 'most-likely' mechanism based on the literature review and analysis performed in this work. The selected modeling concept has the potential to span the CHF conditions from highly subcooled bubbly flow to early stage of annular flow and has been numerically implemented and validated in bubbly flow and coupled with one- and three-dimensional (CFD) two-phase flow codes, in a companion paper. [Le Corre, J.M., Yao, S.C., Amon, C.H., in this issue. A mechanistic model of critical heat flux under subcooled flow boiling conditions for application to one and three-dimensional computer codes. Nucl. Eng. Des.].

  17. Burnout in boiling heat transfer. Part II: subcooled and low quality forced-convection systems

    International Nuclear Information System (INIS)

    Bergles, A.E.

    1977-01-01

    Recent experimental and analytical developments regrading burnout in subcooled and low quality forced-convection systems are reviewed. Much data have been accumulated which clarify the parametric trends and lead to new design correlations for water and a variety of other coolants in both simple and complex geometries. A number of critical experiments and models have been developed to attempt to clarify the burnout mechanism(s) in simpler geometries and power transients

  18. Experimental Investigation of Pressure Drop and Pressure Distribution Along a Heated Channel in Subcooled Flow Boiling

    International Nuclear Information System (INIS)

    Aharon, Y.; Hochbaum, I.; Shai, I.

    2002-01-01

    The state of knowledge relating to pressure drop in subcooled boiling region is very unsatisfactory. That pressure drop is an important factor in considering the design of nuclear reactors because of the possibility of flow excursion during a two phase flow in the channels. In operational systems with multiple flow channels, an increase in pressure drop in one flow channel, can cause the flow to be diverted to other channels. A burnout can occur in the unstable channel

  19. The determination of the initial point of net vapor generation in flow subcooled boiling

    International Nuclear Information System (INIS)

    Yan Changqi; Sun Zhongning

    2000-01-01

    The experimental results for the initial point of net vapor generation in up-flow subcooled boiling in an internally-heated annulus are given. The characteristics of the initial point of net vapor generation and the problem on gamma ray attenuation measurement are discussed. The comparison between the data and a calculation model is given, it is showed that the data agree well with the model

  20. Influence of test tube material on subcooled flow boiling critical heat flux in short vertical tube

    International Nuclear Information System (INIS)

    Hata, Koichi; Shiotsu, Masahiro; Noda, Nobuaki

    2007-01-01

    The steady state subcooled flow boiling critical heat flux (CHF) for the flow velocities (u=4.0 to 13.3 m/s), the inlet subcoolings (ΔT sub,in =48.6 to 154.7 K), the inlet pressure (P in =735.2 to 969.0 kPa) and the increasing heat input (Q 0 exp(t/τ), τ=10, 20 and 33.3 s) are systematically measured with the experimental water loop. The 304 Stainless Steel (SUS304) test tube of inner diameter (d=6 mm), heated length (L=66 mm) and L/d=11 with the inner surface of rough finished (Surface roughness, Ra=3.18 μm), the Cupro Nickel (Cu-Ni 30%) test tube of d=6 mm, L=60 mm and L/d=10 with Ra=0.18 μm and the Platinum (Pt) test tubes of d=3 and 6 mm, L=66.5 and 69.6 mm, and L/d=22.2 and 11.6 respectively with Ra=0.45 μm are used in this work. The CHF data for the SUS304, Cu-Ni 30% and Pt test tubes were compared with SUS304 ones for the wide ranges of d and L/d previously obtained and the values calculated by the authors' published steady state CHF correlations against outlet and inlet subcoolings. The influence of the test tube material on CHF is investigated into details and the dominant mechanism of subcooled flow boiling critical heat flux is discussed. (author)