Screw compressor system for industrial-scale helium refrigerators or industrial ammonia screw compressors for helium refrigeration systems; Schraubenkompressor-System fuer Helium-Grosskaelteanlage oder Ammoniak-Schraubenverdichter aus Industrieanwendungen fuer Helium-Kaelteanlagen

Energy Technology Data Exchange (ETDEWEB)

Fredrich, O.; Mosemann, D.; Zaytsev, D. [GEA Grasso GmbH Refrigeration Technology, Berlin (Germany)

2007-07-01

Material characteristics, requirements and measured data of ammonia and helium compression are compared. The compressor lines for industrial ammonia and helium refrigerators are presented, and important characteristics of the compressors are explained. The test stand for performance measurements with helium and ammonia is described, and results are presented. In spite of the different characteristics of the fluids, the compressor-specific efficiencies (supply characteristic, quality characteristic) were found to be largely identical. The values calculated for helium on the basis of NH3 test runs were found to be realistic, which means that the decades of experience with ammonia in industrial applications can be applied to helium compression as well. The design of screw compressor aggregates (skids) in industrial refrigeration is discussed and illustrated by examples. (orig.)

Mixed helium-3 - helium-4 calorimeter. Very low temperature calorimetry; Calorimetre mixte a helium-3 et helium-4. Calorimetrie a tres basse temperature

Energy Technology Data Exchange (ETDEWEB)

Testard, O [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1966-06-01

A description is given of a double-racket calorimeter using helium-4 and helium-3 as the cryogenic fluids and making it possible to vary the temperature continuously from 0.35 K to 4.2 K. By using an electric thermal regulator together with liquid hydrogen it is possible to extend this range up to about 30 K. In the second part, a review is made of the various, methods available for measuring specific heats. The method actually used in the apparatus previously described is described in detail. The difficulties arising from the use of an exchange gas for the thermal contact have been solved by the use of adsorption pumps. (author) [French] On decrit un calorimetre a double enceinte utilisant comme fluide cryogenique l'helium-4 et l'helium-3 et permettant de varier continuement la temperature de 0,35 K a 4,2 K. L'utilisation d'un regulateur thermique electrique ainsi que celle d'hydrogene, liquide permettent d'etendre cette gamme jusqu'a 30 K environ. Dans une deuxieme partie, on passe en revue les diverses methodes de mesure des chaleurs specifiques. La methode concrete utilisee dans l'appareil precedemment decrit est exposee en detail. Les difficultes inherentes a l'utilisation de gaz d'echange comme agent de contact thermique ont ete levees par la mise en oeuvre de pompes a adsorbant. (auteur)

Dynamics of Superfluid Helium in Low-Gravity

Science.gov (United States)

Frank, David J.

1997-01-01

This report summarizes the work performed under a contract entitled 'Dynamics of Superfluid Helium in Low Gravity'. This project performed verification tests, over a wide range of accelerations of two Computational Fluid Dynamics (CFD) codes of which one incorporates the two-fluid model of superfluid helium (SFHe). Helium was first liquefied in 1908 and not until the 1930s were the properties of helium below 2.2 K observed sufficiently to realize that it did not obey the ordinary physical laws of physics as applied to ordinary liquids. The term superfluidity became associated with these unique observations. The low temperature of SFHe and it's temperature unifonrmity have made it a significant cryogenic coolant for use in space applications in astronomical observations with infrared sensors and in low temperature physics. Superfluid helium has been used in instruments such as the Shuttle Infrared Astronomy Telescope (IRT), the Infrared Astronomy Satellite (IRAS), the Cosmic Background Observatory (COBE), and the Infrared Satellite Observatory (ISO). It is also used in the Space Infrared Telescope (SIRTF), Relativity Mission Satellite formally called Gravity Probe-B (GP-B), and the Test of the Equivalence Principle (STEP) presently under development. For GP-B and STEP, the use of SFHE is used to cool Superconducting Quantum Interference Detectors (SQUIDS) among other parts of the instruments. The Superfluid Helium On-Orbit Transfer (SHOOT) experiment flown in the Shuttle studied the behavior of SFHE. This experiment attempted to get low-gravity slosh data, however, the main emphasis was to study the low-gravity transfer of SFHE from tank to tank. These instruments carried tanks of SFHE of a few hundred liters to 2500 liters. The capability of modeling the behavior of SFHE is important to spacecraft control engineers who must design systems that can overcome disturbances created by the movement of the fluid. In addition instruments such as GP-B and STEP are very

A review of helium gas turbine technology for high-temperature gas-cooled reactors

International Nuclear Information System (INIS)

No, Hee Cheon; Kim, Ji Hwan; Kim, Hyeun Min

2007-01-01

Current High-Temperature Gas-cooled Reactors (HTGRs) are based on a closed brayton cycle with helium gas as the working fluid. Thermodynamic performance of the axial-flow helium gas turbines is of critical concern as it considerably affects the overall cycle efficiency. Helium gas turbines pose some design challenges compared to steam or air turbomachinery because of the physical properties of helium and the uniqueness of the operating conditions at high pressure with low pressure ratio. This report present a review of the helium Brayton cycle experiences in Germany and in Japan. The design and availability of helium gas turbines for HTGR are also presented in this study. We have developed a new throughflow calculation code to calculate the design-point performance of helium gas turbines. Use of the method has been illustrated by applying it to the GTHTR300 reference

A quantitative experiment on the fountain effect in superfluid helium

Science.gov (United States)

Amigó, M. L.; Herrera, T.; Neñer, L.; Peralta Gavensky, L.; Turco, F.; Luzuriaga, J.

2017-09-01

Superfluid helium, a state of matter existing at low temperatures, shows many remarkable properties. One example is the so called fountain effect, where a heater can produce a jet of helium. This converts heat into mechanical motion; a machine with no moving parts, but working only below 2 K. Allen and Jones first demonstrated the effect in 1938, but their work was basically qualitative. We now present data of a quantitative version of the experiment. We have measured the heat supplied, the temperature and the height of the jet produced. We also develop equations, based on the two-fluid model of superfluid helium, that give a satisfactory fit to the data. The experiment has been performed by advanced undergraduate students in our home institution, and illustrates in a vivid way some of the striking properties of the superfluid state.

Hazards of organic working fluids

International Nuclear Information System (INIS)

Silberstein, S.

1977-08-01

We present several brief reviews on working fluids proposed for use in organic Rankine and bi-phase bottoming cycles. There are several general problems with many organic working fluids: flammability, toxicity, and a tendency to leak through seals. Besides, two of the proposed working fluids are to be used at temperatures above the manufacturer's maximum recommended temperature, and one is to be used in a way different from its customary usage. It may, in some cases, be more profitable to first seek alternative working fluids before committing large amounts of time and money to research projects on unsafe working fluids

Pierre Gorce working on a helium pump.

CERN Multimedia

1975-01-01

This type of pump was designed by Mario Morpurgo, to circulate liquid helium in superconducting magnets wound with hollow conductors. M. Morpurgo, Design and construction of a pump for liquid helium, CRYIOGENICS, February 1977, p. 91

Thermal fluid dynamic behavior of coolant helium gas in a typical reactor VHTGR channel of prismatic core; Comportamento termofluidodinamico do gas refrigerante helio em um canal topico de reator VHTGR de nucleo prismatico

Energy Technology Data Exchange (ETDEWEB)

Belo, Allan Cavalcante

2016-08-01

The current studies about the thermal fluid dynamic behavior of the VHTGR core reactors of 4{sup th} generation are commonly developed in 3-D analysis in CFD (computational fluid dynamics), which often requires considerable time and complex mathematical calculations for carrying out these analysis. The purpose of this project is to achieve thermal fluid dynamic analysis of flow of gas helium refrigerant in a typical channel of VHTGR prismatic core reactor evaluating magnitudes of interest such as temperature, pressure and fluid velocity and temperature distribution in the wall of the coolant channel from the development of a computer code in MATLAB considering the flow on one-dimensional channel, thereby significantly reducing the processing time of calculations. The model uses three different references to the physical properties of helium: expressions given by the KTA (German committee of nuclear safety standards), the computational tool REFPROP and a set of constant values for the entire channel. With the use of these three references it is possible to simulate the flow treating the gas both compressible and incompressible. The results showed very close values for the interest quantities and revealed that there are no significant differences in the use of different references used in the project. Another important conclusion to be observed is the independence of helium in the gas compressibility effects on thermal fluid dynamic behavior. The study also indicated that the gas undergoes no severe effects due to high temperature variations in the channel, since this goes in the channel at 914 K and exits at approximately 1263 K, which shows the excellent use of helium as a refrigerant fluid in reactor channels VHTGR. The comparison of results obtained in this work with others in the literature served to confirm the effectiveness of the one-dimensional consideration of method of gas flow in the coolant channel to replace the models made in 3-D for the pressure range

Flow visualization in superfluid helium-4 using He2 molecular tracers

Science.gov (United States)

Guo, Wei

Flow visualization in superfluid helium is challenging, yet crucial for attaining a detailed understanding of quantum turbulence. Two problems have impeded progress: finding and introducing suitable tracers that are small yet visible; and unambiguous interpretation of the tracer motion. We show that metastable He2 triplet molecules are outstanding tracers compared with other particles used in helium. These molecular tracers have small size and relatively simple behavior in superfluid helium: they follow the normal fluid motion at above 1 K and will bind to quantized vortex lines below about 0.6 K. A laser-induced fluorescence technique has been developed for imaging the He2 tracers. We will present our recent experimental work on studying the normal-fluid motion by tracking thin lines of He2 tracers created via femtosecond laser-field ionization in helium. We will also discuss a newly launched experiment on visualizing vortex lines in a magnetically levitated superfluid helium drop by imaging the He2 tracers trapped on the vortex cores. This experiment will enable unprecedented insight into the behavior of a rotating superfluid drop and will untangle several key issues in quantum turbulence research. We acknowledge the support from the National Science Foundation under Grant No. DMR-1507386 and the US Department of Energy under Grant No. DE-FG02 96ER40952.

A PISO-like algorithm to simulate superfluid helium flow with the two-fluid model

CERN Document Server

Soulaine, Cyprien; Allain, Hervé; Baudouy, Bertrand; Van Weelderen, Rob

2015-01-01

This paper presents a segregated algorithm to solve numerically the superfluid helium (He II) equations using the two-fluid model. In order to validate the resulting code and illustrate its potential, different simulations have been performed. First, the flow through a capillary filled with He II with a heated area on one side is simulated and results are compared to analytical solutions in both Landau and Gorter–Mellink flow regimes. Then, transient heat transfer of a forced flow of He II is investigated. Finally, some two-dimensional simulations in a porous medium model are carried out.

Helium-flow measurement using ultrasonic technique

International Nuclear Information System (INIS)

Sondericker, J.H.

1983-01-01

While designing cryogenic instrumentation for the Colliding Beam Accelerator (CBA) helium-distribution system it became clear that accurate measurement of mass flow of helium which varied in temperature from room to sub-cooled conditions would be difficult. Conventional venturi flow meters full scale differential pressure signal would decrease by more than an order of magnitude during cooldown causing unacceptable error at operating temperature. At sub-cooled temperatures, helium would be pumped around cooling loops by an efficient, low head pressure circulating compressor. Additional pressure drop meant more pump work was necessary to compress the fluid resulting in a higher outlet temperature. The ideal mass flowmeter for this application was one which did not add pressure drop to the system, functioned over the entire temperature range, has high resolution and delivers accurate mass flow measurement data. Ultrasonic flow measurement techniques used successfully by the process industry, seemed to meet all the necessary requirements. An extensive search for a supplier of such a device found that none of the commercial stock flowmeters were adaptable to cryogenic service so the development of the instrument was undertaken by the CBA Cryogenic Control and Instrumentation Engineering Group at BNL

Constraints on fluid origins and migration velocities along the Marmara Main Fault (Sea of Marmara, Turkey) using helium isotopes

Science.gov (United States)

Burnard, P.; Bourlange, S.; Henry, P.; Geli, L.; Tryon, M. D.; Natal'in, B.; Sengör, A. M. C.; Özeren, M. S.; Çagatay, M. N.

2012-08-01

Fluids venting from the submarine portion of the Marmara Main Fault (part of the North Anatolian Fault system, Turkey) were sampled in Ti bottles deployed by submersible. The fluids consist of mixtures of fault derived gases, fault related cold seep fluids, and ambient seawater; these components can readily be distinguished using the isotopes of He and the He/Ne ratios. 3He/4He ratios range between 0.03±0.1 and 4.9±0.4 Ra, indicating that both crustal and mantle derived sources of helium are sampled by the fault. The dominant gas in all the samples analyzed is methane with the abundance of CO2 below detection (≤2%) in the mantle rich (high 3He/4He) fluids. This is in contrast to nearly all mantle derived fluids where the C species are dominated by CO2. While high CH4/CO2 ratios may reflect organic or inorganic reactions within the crust which reduce mantle derived CO2 to methane, this is not a priori necessary: we show that simple dilution of mantle fluids with methane produced within local sediments could result in the high 3He/4He, methane rich gases currently emanating from the fault. This observation is supported by an anticorrelation between 3He/4He and C/3He, which is consistent with addition of C and 4He simultaneously to the fluids. The highest 3He/4He ratios were found in the Tekirdag Basin, at the foot of the escarpment bordering the Western Sea of Marmara, where seismic data are consistent with the presence of a fault network at depth which could provide conduits permitting deep-seated fluids to rise to the surface. The lack of recent volcanism, or any evidence of underlying magmatism in the area, along with low temperature fluids, strongly suggests that the 3He-rich helium in these fluids was derived from the mantle itself with the Marmara Main Fault providing a high permeability conduit from the mantle to the surface. Assuming that the mantle source to the fluids originally had a 3He/4He ratio of 6 Ra, the minimum fluid velocities (considering only

Liquid helium target

International Nuclear Information System (INIS)

Fujii, Y.; Kitami, T.; Torikoshi, M.

1984-12-01

A liquid helium target system has been built and used for the experiment on the reaction 4 He(γ, p). The target system has worked satisfactorily; the consumption rate of liquid helium is 360 ml/h and the cryogenic system retains liquid helium for about ten hours. The structure, operation and performance of the target system are reported. (author)

Equation of state of fluid helium at high temperatures and densities

Science.gov (United States)

Cai, Lingcang; Chen, Qifeng; Gu, Yunjun; Zhang, Ying; Zhou, Xianming; Jing, Fuqian

2005-03-01

Hugoniot curves and shock temperatures of gas helium with initial temperature 293 K and three initial pressures 0.6, 1.2, and 5.0 MPa were measured up to 15000 K using a two-stage light-gas gun and transient radiation pyrometer. It was found that the calculated Hugoniot EOS of gas helium at the same initial pressure using Saha equation with Debye-Hückel correction was in good agreement with the experimental data. The curve of the calculated shock wave velocity with the particle velocity of gas helium which is shocked from the initial pressure 5 MPa and temperature 293 K, i.e., the D ≈ u relation, D= C 0+λ u ( uionization degree of the shocked gas helium reaches 10-3.

CFD Analysis on the Passive Heat Removal by Helium and Air in the Canister of Spent Fuel Dry Storage System

Energy Technology Data Exchange (ETDEWEB)

Shin, Do Young; Jeong, Ui Ju; Kim, Sung Joong [Hanyang University, Seoul (Korea, Republic of)

2016-05-15

In the current commercial design, the canister of the dry storage system is mainly backfilled with helium gas. Helium gas shows very conductive behavior due to high thermal conductivity and small density change with temperature. However, other gases such as air, argon, or nitrogen are expected to show effective convective behavior. Thus these are also considered as candidates for the backfill gas to provide effective coolability. In this study, to compare the dominant cooling mechanism and effectiveness of cooling between helium gas and air, a computational fluid dynamics (CFD) analysis for the canister of spent fuel dry storage system with backfill gas of helium and air is carried out. In this study, CFD simulations for the helium and air backfilled gas for dry storage system canister were carried out using ANSYS FLUENT code. For the comparison work, two backfilled fluids were modeled with same initial and boundary conditions. The observed major difference can be summarized as follows. - The simulation results showed the difference in dominant heat removal mechanism. Conduction for helium, and convection for air considering Reynolds number distribution. - The temperature gradient inside the fuel assembly showed that in case of air, more effective heat mixing occurred compared to helium.

Tribological behavior of zirconium coatings in high temperature helium

International Nuclear Information System (INIS)

Cachon, Lionel; Albaladejo, Serge; Taraud, Pascal

2005-01-01

In France, a comprehensive research and development program is leaded by the CEA, since 2001, for the Gas Cooled Reactor (GCR) project using helium as cooling fluid, in order to establish the feasibility of the technology of an early VHTR prototype to be started by 2015, and then to qualify the generic VHTR technology, so as to meet similar objectives for the GFR. In this frame a tribology program has been launched. The purpose of the work presented in this paper is to describe the CEA Helium tribology study: high temperature gas cooled reactors require wear protection (thermal barriers, control rod drive mechanisms, reactor internals, ...). Tests in helium atmosphere are necessary to be fully representative of tribological environments and finally to check the possible materials or coatings which can provide a reliable answer to these situations. The main characteristics and first experimental results are thus described. This paper focus on tribology tests leaded in the temperature range 800-1000degC, on ceramic (ZrO 2 -Y 2 O 3 ) with and without solid lubricant like CaF2). (author)

Quantum fluid dynamics based current-density functional study of a helium atom in a strong time-dependent magnetic field

International Nuclear Information System (INIS)

Vikas

2011-01-01

Evolution of the helium atom in a strong time-dependent (TD) magnetic field (B) of strength up to 10 11 G is investigated through a quantum fluid dynamics (QFD) based current-density functional theory (CDFT). The TD-QFD-CDFT computations are performed through numerical solution of a single generalized nonlinear Schroedinger equation employing vector exchange-correlation potentials and scalar exchange-correlation density functionals that depend both on the electronic charge-density and the current-density. The results are compared with that obtained from a B-TD-QFD-DFT approach (based on conventional TD-DFT) under similar numerical constraints but employing only scalar exchange-correlation potential dependent on electronic charge-density only. The B-TD-QFD-DFT approach, at a particular TD magnetic field-strength, yields electronic charge- and current-densities as well as exchange-correlation potential resembling with that obtained from the time-independent studies involving static (time-independent) magnetic fields. However, TD-QFD-CDFT electronic charge- and current-densities along with the exchange-correlation potential and energy differ significantly from that obtained using B-TD-QFD-DFT approach, particularly at field-strengths >10 9 G, representing dynamical effects of a TD field. The work concludes that when a helium atom is subjected to a strong TD magnetic field of order >10 9 G, the conventional TD-DFT based approach differs 'dynamically' from the CDFT based approach under similar computational constraints. (author)

Structure design and simulation research of active magnetic bearing for helium centrifugal cold compressor

Science.gov (United States)

Y Zhang, S.; Pan, W.; Wei, C. B.; Wu, J. H.

2017-12-01

Helium centrifugal cold compressors are utilized to pump gaseous helium from saturated liquid helium tank to obtain super-fluid helium in cryogenic refrigeration system, which is now being developed at TIPC, CAS. Active magnetic bearing (AMB) is replacing traditional oil-fed bearing as the optimal supporting assembly for cold compressor because of its many advantages: free of contact, high rotation speed, no lubrication and so on. In this paper, five degrees of freedom for AMB are developed for the helium centrifugal cold compressor application. The structure parameters of the axial and radial magnetic bearings as well as hardware and software of the electronic control system is discussed in detail. Based on modal analysis and critical speeds calculation, a control strategy combining PID arithmetic with other phase compensators is proposed. Simulation results demonstrate that the control method not only stables AMB system but also guarantees good performance of closed-loop behaviour. The prior research work offers important base and experience for test and application of AMB experimental platform for system centrifugal cold compressor.

Helium turbomachinery operating experience from gas turbine power plants and test facilities

International Nuclear Information System (INIS)

McDonald, Colin F.

2012-01-01

The closed-cycle gas turbine, pioneered and deployed in Europe, is not well known in the USA. Since nuclear power plant studies currently being conducted in several countries involve the coupling of a high temperature gas-cooled nuclear reactor with a helium closed-cycle gas turbine power conversion system, the experience gained from operated helium turbomachinery is the focus of this paper. A study done as early as 1945 foresaw the use of a helium closed-cycle gas turbine coupled with a high temperature gas-cooled nuclear reactor, and some two decades later this was investigated but not implemented because of lack of technology readiness. However, the first practical use of helium as a gas turbine working fluid was recognized for cryogenic processes, and the first two small fossil-fired helium gas turbines to operate were in the USA for air liquefaction and nitrogen production facilities. In the 1970's a larger helium gas turbine plant and helium test facilities were built and operated in Germany to establish technology bases for a projected future high efficiency large nuclear gas turbine power plant concept. This review paper covers the experience gained, and the lessons learned from the operation of helium gas turbine plants and related test facilities, and puts these into perspective since over three decades have passed since they were deployed. An understanding of the many unexpected events encountered, and how the problems, some of them serious, were resolved is important to avoid them being replicated in future helium turbomachines. The valuable lessons learned in the past, in many cases the hard way, particularly from the operation in Germany of the Oberhausen II 50 MWe helium gas turbine plant, and the technical know-how gained from the formidable HHV helium turbine test facility, are viewed as being germane in the context of current helium turbomachine design work being done for future high efficiency nuclear gas turbine plant concepts. - Highlights: �

High Temperature Operational Experiences of Helium Experimental Loop

International Nuclear Information System (INIS)

Kim, Chan Soo; Hong, Sung-Deok; Kim, Eung-Seon; Kim, Min Hwan

2015-01-01

The development of high temperature components of VHTR is very important because of its higher operation temperature than that of a common light water reactor and high pressure industrial process. The development of high temperature components requires the large helium loop. Many countries have high temperature helium loops or a plan for its construction. Table 1 shows various international state-of-the-art of high temperature and high pressure gas loops. HELP performance test results show that there is no problem in operation of HELP at the very high temperature experimental condition. These experimental results also provide the basic information for very high temperature operation with bench-scale intermediate heat exchanger prototype in HELP. In the future, various heat exchanger tests will give us the experimental data for GAMMA+ validation about transient T/H behavior of the IHX prototype and the optimization of the working fluid in the intermediate loop

Study of reverse Brayton cryocooler with Helium-Neon mixture for HTS cable

Science.gov (United States)

Dhillon, A. K.; Ghosh, P.

2017-12-01

As observed in the earlier studies, helium is more efficient than neon as a refrigerant in a reverse Brayton cryocooler (RBC) from the thermodynamic point of view. However, the lower molecular weight of helium leads to higher refrigerant inventory as compared to neon. Thus, helium is suitable to realize the high thermodynamic efficiency of RBC whereas neon is appropriate for the compactness of the RBC. A binary mixture of helium and neon can be used to achieve high thermodynamic efficiency in the compact reverse Brayton cycle (RBC) based cryocooler. In this paper, an attempt has been made to analyze the thermodynamic performance of the RBC with a binary mixture of helium and neon as the working fluid to provide 1 kW cooling load for high temperature superconductor (HTS) power cables working with a temperature range of 50 K to 70 K. The basic RBC is simulated using Aspen HYSYS V8.6®, a commercial process simulator. Sizing of each component based on the optimized process parameters for each refrigerant is performed based on a computer code developed using Engineering Equation Solver (EES-V9.1). The recommendation is provided for the optimum mixture composition of the refrigerant based on the trade-off factors like thermodynamic efficiency such as the exergy efficiency and equipment considerations. The outcome of this study may be useful for recommending a suitable refrigerant for the RBC operating at a temperature level of 50 K to 70 K.

Working fluid selection for organic Rankine cycles - Impact of uncertainty of fluid properties

DEFF Research Database (Denmark)

Frutiger, Jerome; Andreasen, Jesper Graa; Liu, Wei

2016-01-01

of processmodels and constraints 2) selection of property models, i.e. Penge Robinson equation of state 3)screening of 1965 possible working fluid candidates including identification of optimal process parametersbased on Monte Carlo sampling 4) propagating uncertainty of fluid parameters to the ORC netpower output......This study presents a generic methodology to select working fluids for ORC (Organic Rankine Cycles)taking into account property uncertainties of the working fluids. A Monte Carlo procedure is described as a tool to propagate the influence of the input uncertainty of the fluid parameters on the ORC....... The net power outputs of all the feasible working fluids were ranked including their uncertainties. The method could propagate and quantify the input property uncertainty of the fluidproperty parameters to the ORC model, giving an additional dimension to the fluid selection process. In the given analysis...

A new method used to evaluate organic working fluids

International Nuclear Information System (INIS)

Zhang, Xinxin; He, Maogang; Wang, Jingfu

2014-01-01

In this paper, we propose a method named “Weight Classification-Hasse Dominance” to evaluate organic working fluids. This new method combines the advantages of both the method of weight determination and the Hasse Diagram Technique (HDT). It can be used to evaluate the thermodynamic performance, environmental protection indicator, and safety requirement of organic working fluid simultaneously. This evaluation method can offer good reference for working fluid selection. Using this method, the organic working fluids which have been phased out and will be phased out by the Montreal Protocol including CFCs (chlorofluorocarbons), HCFCs (hydrochlorofluorocarbons), and HFCs (hydrofluorocarbons) were evaluated. Moreover, HCs (hydrocarbons) can be considered as a completely different kind of organic working fluid from CFCs, HCFCs, and HFCs according to the comparison based on this new evaluation method. - Highlights: • We propose a new method used to evaluate organic working fluids. • This evaluation method can offer good reference for working fluid selection. • CFC, HCFC, and HFC working fluids were evaluated using this evaluation method. • HC can be considered as a totally different working fluid from CFC, HCFC, and HFC

What happens to liquid helium 3 at very low temperatures

International Nuclear Information System (INIS)

Dobbs, E.R.; Bedford Coll., London

1976-01-01

Liquid helium 3 forms a highly compressible, quantum fluid of fermions at its boiling point of 3.2 K. As it is cooled this fluid condenses into a viscous Fermi liquid until at temperatures of a few millikelvin it is transformed into one of two superfluids, A or B. The A phase is an anisotoropic superfluid of the Anderson-Brinkman-Morel type, while the B phase is an isotropic superfluid of the Balian-Werthamer type. The properties of these superfluids will be discussed and contrasted with those of superfluid helium 4 and metallic superconductors. (orig.) [de

Big bang nucleosynthesis with a stiff fluid

International Nuclear Information System (INIS)

Dutta, Sourish; Scherrer, Robert J.

2010-01-01

Models that lead to a cosmological stiff fluid component, with a density ρ S that scales as a -6 , where a is the scale factor, have been proposed recently in a variety of contexts. We calculate numerically the effect of such a stiff fluid on the primordial element abundances. Because the stiff fluid energy density decreases with the scale factor more rapidly than radiation, it produces a relatively larger change in the primordial helium-4 abundance than in the other element abundances, relative to the changes produced by an additional radiation component. We show that the helium-4 abundance varies linearly with the density of the stiff fluid at a fixed fiducial temperature. Taking ρ S10 and ρ R10 to be the stiff fluid energy density and the standard density in relativistic particles, respectively, at T=10 MeV, we find that the change in the primordial helium abundance is well-fit by ΔY p =0.00024(ρ S10 /ρ R10 ). The changes in the helium-4 abundance produced by additional radiation or by a stiff fluid are identical when these two components have equal density at a 'pivot temperature', T * , where we find T * =0.55 MeV. Current estimates of the primordial 4 He abundance give the constraint on a stiff fluid energy density of ρ S10 /ρ R10 <30.

Exploring the structural controls on helium, nitrogen and carbon isotope signatures in hydrothermal fluids along an intra-arc fault system

Science.gov (United States)

Tardani, Daniele; Reich, Martin; Roulleau, Emilie; Takahata, Naoto; Sano, Yuji; Pérez-Flores, Pamela; Sánchez-Alfaro, Pablo; Cembrano, José; Arancibia, Gloria

2016-07-01

There is a general agreement that fault-fracture meshes exert a primary control on fluid flow in both volcanic/magmatic and geothermal/hydrothermal systems. For example, in geothermal systems and epithermal gold deposits, optimally oriented faults and fractures play a key role in promoting fluid flow through high vertical permeability pathways. In the Southern Volcanic Zone (SVZ) of the Chilean Andes, both volcanism and hydrothermal activity are strongly controlled by the Liquiñe-Ofqui Fault System (LOFS), an intra-arc, strike-slip fault, and by the Arc-oblique Long-lived Basement Fault System (ALFS), a set of transpressive NW-striking faults. However, the role that principal and subsidiary fault systems exert on magma degassing, hydrothermal fluid flow and fluid compositions remains poorly constrained. In this study we report new helium, carbon and nitrogen isotope data (3He/4He, δ13C-CO2 and δ15N) of a suite of fumarole and hot spring gas samples from 23 volcanic/geothermal localities that are spatially associated with either the LOFS or the ALFS in the central part of the SVZ. The dataset is characterized by a wide range of 3He/4He ratios (3.39 Ra to 7.53 Ra, where Ra = (3He/4He)air), δ13C-CO2 values (-7.44‰ to -49.41‰) and δ15N values (0.02‰ to 4.93‰). The regional variations in 3He/4He, δ13C-CO2 and δ15N values are remarkably consistent with those reported for 87Sr/86Sr in lavas along the studied segment, which are strongly controlled by the regional spatial distribution of faults. Two fumaroles gas samples associated with the northern ;horsetail; transtensional termination of the LOFS are the only datapoints showing uncontaminated MORB-like 3He/4He signatures. In contrast, the dominant mechanism controlling helium isotope ratios of hydrothermal systems towards the south appears to be the mixing between mantle-derived helium and a radiogenic component derived from, e.g., magmatic assimilation of 4He-rich country rocks or contamination during the

Closed-cycle gas turbine working fluids

International Nuclear Information System (INIS)

Lee, J.C.; Campbell, J. Jr.; Wright, D.E.

1981-01-01

Characteristic requirements of a closed-cycle gas turbine (CCGT) working fluid were identified and the effects of their thermodynamic and transport properties on the CCGT cycle performance, required heat exchanger surface area and metal operating temperature, cycle operating pressure levels, and the turbomachinery design were investigated. Material compatibility, thermal and chemical stability, safety, cost, and availability of the working fluid were also considered in the study. This paper also discusses CCGT working fluids utilizing mixtures of two or more pure gases. Some mixtures of gases exhibit pronounced synergetic effects on their characteristic properties including viscosity, thermal conductivity and Prandtl number, resulting in desirable heat transfer properties and high molecular weights. 21 refs

Helium behaviour in nuclear glasses

International Nuclear Information System (INIS)

Fares, T.

2011-01-01

The present thesis focuses on the study of helium behavior in R7T7 nuclear waste glass. Helium is generated by the minor actinides alpha decays incorporated in the glass matrix. Therefore, four types of materials were used in this work. These are non radioactive R7T7 glasses saturated with helium under pressure, glasses implanted with 3 He + ions, glasses doped with curium and glasses irradiated in nuclear reactor. The study of helium solubility in saturated R7T7 glass has shown that helium atoms are inserted in the glass free volume. The results yielded a solubility of about 10 16 at. cm -3 atm. -1 . The incorporation limit of helium in this type of glass has been determined; its value amounted to about 2*10 21 at. cm -3 , corresponding to 2.5 at.%. Diffusion studies have shown that the helium migration is controlled by the single population dissolved in the glass free volume. An ideal diffusion model was used to simulate the helium release data which allowed to determine diffusion coefficients obeying to the following Arrhenius law: D = D 0 exp(-E a /kBT), where D 0 = 2.2*10 -2 and 5.4*10 -3 cm 2 s -1 and E a = 0.61 eV for the helium saturated and the curium doped glass respectively. These results reflect a thermally activated diffusion mechanism which seems to be not influenced by the glass radiation damage and helium concentrations studied in the present work (up to 8*10 19 at. g -1 , corresponding to 0.1 at.%). Characterizations of the macroscopic, structural and microstructural properties of glasses irradiated in nuclear reactor did not reveal any impact associated with the presence of helium at high concentrations. The observed modifications i.e. a swelling of 0.7 %, a decrease in hardness by 38 %, an increase between 8 and 34 % of the fracture toughness and a stabilization of the glass structure under irradiation, were attributed to the glass nuclear damage induced by the irradiation in reactor. Characterizations by SEM and TEM of R7T7 glasses implanted

A 3-D model of superfluid helium suitable for numerical analysis

CERN Document Server

Darve, C; Van Sciver, S W

2009-01-01

The two-fluid description is a very successful phenomenological representation of the properties of Helium II. A 3-D model suitable for numerical analysis based on the Landau-Khalatnikov description of Helium II is proposed. In this paper we introduce a system of partial differential equations that is both complete and consistent as well as practical, to be used for a 3-D solution of the flow of Helium II. The development of a 3-D numerical model for Helium II is motivated by the need to validate experimental results obtained by observing the normal component velocity distribution in a Helium II thermal counter-flow using the Particle Image Velocimetry (PIV) technique.

Critical Temperature Differences of a Standing Wave Thermoacoustic Prime Mover with Various Helium-Based Binary Mixture Working Gases

Science.gov (United States)

Setiawan, Ikhsan; Nohtomi, Makoto; Katsuta, Masafumi

2015-06-01

Thermoacoustic prime movers are energy conversion devices which convert thermal energy into acoustic work. The devices are environmentally friendly because they do not produce any exhaust gases. In addition, they can utilize clean energy such as solar-thermal energy or waste heat from internal combustion engines as the heat sources. The output mechanical work of thermoacoustic prime movers are usually used to drive a thermoacoustic refrigerator or to generate electricity. A thermoacoustic prime mover with low critical temperature difference is desired when we intend to utilize low quality of heat sources such as waste heat and sun light. The critical temperature difference can be significantly influenced by the kinds of working gases inside the resonator and stack's channels of the device. Generally, helium gas is preferred as the working gas due to its high sound speed which together with high mean pressure will yield high acoustic power per unit volume of the device. Moreover, adding a small amount of a heavy gas to helium gas may improve the efficiency of thermoacoustic devices. This paper presents numerical study and estimation of the critical temperature differences of a standing wave thermoacoustic prime mover with various helium-based binary-mixture working gases. It is found that mixing helium (He) gas with other common gases, namely argon (Ar), nitrogen (N2), oxygen (O2), and carbon dioxide (CO2), at appropriate pressures and molar compositions, reduce the critical temperature differences to lower than those of the individual components of the gas mixtures. In addition, the optimum mole fractions of Hegas which give the minimum critical temperature differences are shifted to larger values as the pressure increases, and tends to be constant at around 0.7 when the pressure increases more than 2 MPa. However, the minimum critical temperature differences slightly increase as the pressure increases to higher than 1.5 MPa. Furthermore, we found that the lowest

Parametric investigation of working fluids for organic Rankine cycle applications

International Nuclear Information System (INIS)

Brown, J. Steven; Brignoli, Riccardo; Quine, Timothy

2015-01-01

This paper investigates working fluids for organic Rankine cycle (ORC) applications with a goal of identifying “ideal” working fluids for five renewable/alternative energy sources. It employs a methodology for screening and comparing with good engineering accuracy the thermodynamic performance potential of ORC operating with working fluids that are not well characterized experimentally or by high-accuracy equations of state. A wide range of “theoretical” working fluids are investigated with the goals to identify potential alternative working fluids and to guide future research and development efforts of working fluids. The “theoretical” working fluids investigated are described in terms of critical state properties, acentric factor, and ideal gas specific heat capacity at constant pressure and are obtained by parametrically varying each of these parameters. The performances of these “theoretical” working fluids are compared to the performances of several “real” working fluids. The study suggests a working fluid's critical temperature and its critical ideal gas molar heat capacity have the largest impact on the cycle efficiency and volumetric work output, with “ideal” working fluids for high efficiency possessing critical temperatures on the order of 100%–150% of the source temperature and possessing intermediate values of critical ideal gas molar heat capacity. - Highlights: • “Ideal” working fluids are investigated for organic Rankine cycles (ORC). • The thermodynamic space of “ideal” working fluids is parametrically investigated. • Five low- and high-temperature ORC applications are investigated. • 1620 “ideal” and several “real” working fluids per application are investigated.

High Reynolds number flows using liquid and gaseous helium

International Nuclear Information System (INIS)

Donnelly, R.J.

1991-01-01

Consideration is given to liquid and gaseous helium as test fluids, high Reynolds number test requirements in low speed aerodynamics, the measurement of subsonic flow around an appended body of revolution at cryogenic conditions in the NTF, water tunnels, flow visualization, the six component magnetic suspension system for wind tunnel testing, and recent aerodynamic measurements with magnetic suspension systems. Attention is also given to application of a flow visualization technique to a superflow experiment, experimental investigations of He II flows at high Reynolds numbers, a study of homogeneous turbulence in superfluid helium, and thermal convection in liquid helium

Stirling engine with air working fluid

Science.gov (United States)

Corey, John A.

1985-01-01

A Stirling engine capable of utilizing air as a working fluid which includes a compact heat exchange module which includes heating tube units, regenerator and cooler positioned about the combustion chamber. This arrangement has the purpose and effect of allowing the construction of an efficient, high-speed, high power-density engine without the use of difficult to seal light gases as working fluids.

Working fluid selection for organic Rankine cycles - Impact of uncertainty of fluid properties

DEFF Research Database (Denmark)

Frutiger, Jerome; Andreasen, Jesper Graa; Liu, Wei

2016-01-01

This study presents a generic methodology to select working fluids for ORC (Organic Rankine Cycles)taking into account property uncertainties of the working fluids. A Monte Carlo procedure is described as a tool to propagate the influence of the input uncertainty of the fluid parameters on the ORC...... modeloutput, and provides the 95%-confidence interval of the net power output with respect to the fluid property uncertainties. The methodology has been applied to a molecular design problem for an ORCusing a low-temperature heat source and consisted of the following four parts: 1) formulation...... of processmodels and constraints 2) selection of property models, i.e. Penge Robinson equation of state 3)screening of 1965 possible working fluid candidates including identification of optimal process parametersbased on Monte Carlo sampling 4) propagating uncertainty of fluid parameters to the ORC netpower output...

The 1/3-scale aerodynamics performance test of helium compressor for GTHTR300 turbo machine of JAERI (step 1)

International Nuclear Information System (INIS)

Takada, Shoji; Takizuka, Takakazu; Kunitomi, Kazuhiko; Xing, Yan

2003-01-01

A program for research and development on aerodynamics in a helium gas compressor was planned for the power conversion system of the Gas Turbine High Temperature Reactor (GTHTR300). The three-dimensional aerodynamic design of the compressor achieved a high polytropic efficiency of 90%, keeping a sufficient surge margin over 30%. To validate the design of the helium gas compressor of GTHTR300, aerodynamic performance tests were planned, and a 1/3-scale, 4-stage compressor model was designed. In the tests, the performance data of the helium gas compressor model will be acquired by using helium gas as a working fluid. The maximum design pressure at the model inlet is 0.88 MPa, which allows the Reynolds number to be sufficiently high. The present study is entrusted from the Ministry of Education, Culture, Sports, Science and Technology of Japan. (author)

Structural Controls on Helium, Nitrogen and Carbon Isotope Signatures in Geothermal Fluids Along the Liquiñe-Ofqui Fault System, Southern Chile.

Science.gov (United States)

Tardani, D.; Reich, M.; Roulleau, E.; Sano, Y.; Takahata, N.; Perez-Flores, P.; Sanchez-Alfaro, P.; Cembrano, J. M.; Arancibia, G.

2016-12-01

There is a general agreement that fault-fracture meshes exert a primary control on fluid flow in both volcanic/magmatic and geothermal/hydrothermal systems. In the Southern Volcanic Zone (SVZ) of the Chilean Andes, both volcanism and hydrothermal activity are spatially controlled by the Liquiñe-Ofqui Fault System (LOFS), an intra-arc, strike-slip fault, and by the Arc-oblique Long-lived Basement Fault System (ALFS), a set of transpressive NW-striking faults. However, the role that principal and subsidiary fault systems exert on magma degassing, hydrothermal fluid flow and fluid compositions remains poorly constrained. In this study we report new helium, carbon and nitrogen isotope data (3He/4He, d13C-CO2 and d15N) of a suite of fumarole and hot spring gas samples from 23 volcanic/geothermal localities that are spatially associated with either the LOFS or the ALFS in the central part of the SVZ. The dataset is characterized by a wide range of 3He/4He ratios (3.39 Ra to 7.53 Ra, where Ra = (3He/4He)air), d13C-CO2 values (-7.44‰ to -49.41‰) and d15N values (0.02‰to 4.93‰). The regional variations in 3He/4He, d13C-CO2 and d15N values are consistent with those reported for 87Sr/86Sr in lavas along the studied segment, which are controlled by the regional faults distribution. Two samples associated with the northern transtensional termination of the LOFS are the only datapoints showing pure MORB-like helium signatures. Whereas, towards the south the mantle-derived helium mixed with radiogenic component derived from magmatic assimilation of 4He-rich country rocks or contamination during the passage of the fluids through the upper crust. The degree of 4He contamination is related with the faults controlling the occurrence of volcanic and geothermal systems, with the most contaminated values associated with NW-striking structures. This is confirmed by d15N values that show increased mixing with crustal sediments and meteoric waters along NW faults (AFLS), while d13

Brush seal leakage performance with gaseous working fluids at static and low rotor speed conditions

Science.gov (United States)

Carlile, Julie A.; Hendricks, Robert C.; Yoder, Dennis A.

1992-01-01

The leakage performance of a brush seal with gaseous working fluids at static and low rotor speed conditions was studied. The leakage results included for air, helium, and carbon dioxide at several bristle/rotor interferences. Also, the effects of packing a lubricant into the bristles and also of reversing the pressure drop across the seal were studied. Results were compared to that of an annular seal at similar operating conditions. In order to generalize the results, they were correlated using corresponding state theory. The brush seal tested had a bore diameter of 3.792 cm (1.4930 in.), a fence height of 0.0635 cm (0.025 in.), and 1800 bristles/cm circumference (4500 bristles/in. circumference). Various bristle/rotor radial interferences were achieved by using a tapered rotor. The brush seal reduced the leakage in comparison to the annular seal, up to 9.5 times. Reversing the pressure drop across the brush seal produced leakage rates approximately the same as that of the annular seal. Addition of a lubricant reduced the leakage by 2.5 times. The air and carbon dioxide data were successfully correlated using corresponding state theory. However, the helium data followed a different curve than the air and carbon dioxide data.

Working Fluids for Increasing Capacities of Heat Pipes

Science.gov (United States)

Chao, David F.; Zhang, Nengli

2004-01-01

A theoretical and experimental investigation has shown that the capacities of heat pipes can be increased through suitable reformulation of their working fluids. The surface tensions of all of the working fluids heretofore used in heat pipes decrease with temperature. As explained in more detail below, the limits on the performance of a heat pipe are associated with the decrease in the surface tension of the working fluid with temperature, and so one can enhance performance by reformulating the working fluid so that its surface tension increases with temperature. This improvement is applicable to almost any kind of heat pipe in almost any environment. The heat-transfer capacity of a heat pipe in its normal operating-temperature range is subject to a capillary limit and a boiling limit. Both of these limits are associated with the temperature dependence of surface tension of the working fluid. In the case of a traditional working fluid, the decrease in surface tension with temperature causes a body of the liquid phase of the working fluid to move toward a region of lower temperature, thus preventing the desired spreading of the liquid in the heated portion of the heat pipe. As a result, the available capillary-pressure pumping head decreases as the temperature of the evaporator end of the heat pipe increases, and operation becomes unstable. Water has widely been used as a working fluid in heat pipes. Because the surface tension of water decreases with increasing temperature, the heat loads and other aspects of performance of heat pipes that contain water are limited. Dilute aqueous solutions of long-chain alcohols have shown promise as substitutes for water that can offer improved performance, because these solutions exhibit unusual surface-tension characteristics: Experiments have shown that in the cases of an aqueous solution of an alcohol, the molecules of which contain chains of more than four carbon atoms, the surface tension increases with temperature when the

Energetics and dynamics of excess electrons in simple fluids

International Nuclear Information System (INIS)

Space, B.

1992-01-01

Excess electronic dynamical and equilibrium properties are modeled in both polarizable and nonpolarizable noble gas fluids. Explicit dynamical calculations are carried out for excess electrons in fluid helium, where excess electronic eigenstates are localized. Energetics and dynamics are considered for fluids which span the entire range of polarizability present in the rare gases. Excess electronic eigenstates and eigenvalues are calculated for fluids of helium, argon and xenon. Both equilibrium and dynamical information is obtained from the calculation of these wavefunctions. A surface hopping trajectory method for studying nonadiabatic excess electronic relaxation in condensed systems is used to explore the nonadiabatic relaxation after photoexciting an equilibrated excess electron in dense fluid helium. The different types on nonadiabatic phenomena which are important in excess electronic relaxation are surveyed. The same surface hopping trajectory method is also used to study the rapid nonadiabatic relaxation after an excess electron is injected into unperturbed fluid helium. Several distinctively different relaxation processes, characterized by their relative importance at different times during the relaxation to a localized equilibrium state, are detailed. Though the dynamical properties of excess electrons under the conditions considered here have never been studied before, the behavior is remarkably similar to that observed in both experimental and theoretical studies of electron hydration dynamics, indicating that the processes described may be very general relaxation mechanisms for localization and trapping in fluids. Additionally, ground state energies of an excess electron, e 0 , are computed as a function of solvent density using model electron-atom pseudopotentials in fluid helium, argon, and xenon. The nonuniqueness of the pseudopotential description of electron-molecule interactions is demonstrated

Superfluid helium-4: An introductory review

International Nuclear Information System (INIS)

Vinen, W.F.

1983-01-01

Helium was first liquefied by Kamerlingh Onnes in Leiden in July 1908, an achievement that followed much careful and painstaking work. On the same day Onnes reduced the temperature of his helium to a value approaching lK, and he must therefore have produced and observed the superfluid phase. These experimental discoveries led very quickly to a series of remarkable theoretical contributions that laid the foundations for all subsequent work. The period since the second world war has of course seen an enormous amount of work on superfluid helium-4. In reviewing it the author tries to see it in terms of two threads: one originating from Landau; the other from London

Resource letter SH-1: superfluid helium

International Nuclear Information System (INIS)

Hallock, R.B.

1982-01-01

The resource letter covers the general subject of superfluid helium and treats 3 He and 3 He-- 4 He mixtures as well as 4 He. No effort has been made to include the fascinating experiments on either solid helium or the equally fascinating work on adsorbed helium where the helium coverage is below that necessary for superfluidity. An earlier resource letter by C. T. Lane [Am. J. Phys. 35, 367 (1967)] may be consulted for additional comments on some of the cited earlier manuscripts, but the present work is self-contained and may be used independently. Many high-quality research reports have not been cited here. Rather, the author has tried in most cases to include works particularly readable or relevant. There is a relatively heavy emphasis on experimental references. The primary reason is that these works tend to be more generally readable. No doubt some works that might have been included, have not, and for this the author takes responsibility with apology. Articles selected for incorporation in a reprint volume (to be published separately by the American Association of Physics Teachers) are marked with an asterisk(*). Following each referenced work the general level of difficulty is indicated by E, I, or A for elementary, intermediate, or advanced

Thirty years of screw compressors for helium; Dreissig Jahre Schraubenkompressoren fuer Helium

Energy Technology Data Exchange (ETDEWEB)

Wahl, H. [Kaeser Kompressoren GmbH, Coburg (Germany). Technisches Buero/Auftragskonstruktion

2007-07-01

KAESER helium compressors, as well as their other industrial compressors, will be further developed with the intention to improve the availability and reliability of helium liquefaction systems. Further improvement of compressor and control system efficiency will ensure a low and sustainable operating cost. Fast supply of replacement parts with several years of warranty is ensured by a world-wide distribution system and is also worked on continuously. (orig.)

Helium isotopes in rocks, waters and gases of the earth's crust

International Nuclear Information System (INIS)

Tolstikhin, L.H.

1984-01-01

In this chapter the distribution of helium isotopes in various samples (rocks, minerals, terrestrial fluids, gases etc.) is interpreted from the genetic point of view, namely what sources and processes provide the abundance of helium isotopes observed in a sample. The mixing of mantle, juvenile helium with pure radiogenic helium is the main process responsible for the helium isotope composition in any sample of the earth's crust, the share of each component (reflected in the 3 He/ 4 He ratio) depending on the history of the tectono-magnetic activity in the given region. A specific chemical composition of a rock or mineral, peculiarities of losses or trapping and a peculiar kind of distribution of radioactive elements can lead to unusual isotopic ratios of 3 He/ 4 He in radiogenic helium. Lastly, technogenic radioactive isotopes are widespread in nature; one of them, tritium ( 3 H), yields 3 He excess in terrestrial waters. (orig.)

Bed system performance in helium circulation mode

Energy Technology Data Exchange (ETDEWEB)

Kim, Yean Jin; Jung, Kwang Jin; Ahn, Do Hee; Chung, Hong Suk [UST, Daejeon (Korea, Republic of); Kang, Hee Suk [KAERI, Daejeon (Korea, Republic of); Yun, Sei Hun [NFRI, Deajeon (Korea, Republic of)

2016-05-15

As a part of the International Thermonuclear Experimental Reactor (ITER) Project, We have conducted an experiment for storing hydrogen to depleted uranium and zirconium cobalt. The helium blanket effect has been observed in experiments using metal hydrides. The collapse of the hydrogen isotopes are accompanied by the decay heat and helium-3. Helium-3 dramatically reduces the hydrogen isotope storage capacity by surrounding the metal. This phenomenon is called a helium blanket effect. In addition the authors are working on the recovery and removal techniques of helium-3. In this paper, we discuss the equipment used to test the helium blanket effect and the results of a helium circulation experiment. The helium-3 produced surrounds the storage material surface and thus disturbs the reaction of the storage material and the hydrogen isotope. Even if the amount of helium-3 is small, the storage capacity of the SDS bed significantly drops. This phenomenon is the helium blanket effect. To resolve this phenomenon, a circulating loop was introduced. Using a circulating system, helium can be separated from the storage material. We made a helium loop that includes a ZrCo bed. Then using a metal bellows pump, we tested the helium circulation.

Effects of cyclic mean pressure of helium gas on performance of integral crank driven stirling cryocooler

Energy Technology Data Exchange (ETDEWEB)

Hong, Yong Ju; Ko, Jun Seok; Kim, Hyo Bong; Park, Seong Je [Korea Institute of Machinery and Materials, Changwon (Korea, Republic of)

2016-09-15

An integral crank driven Stirling cryocooler is solidly based on concepts of direct IR detector mounting on the cryocooler's cold finger, and the integral construction of the cryocooler and Dewar envelope. Performance factors of the cryocooler depend on operating conditions of the cryocooler such as a cyclic mean pressure of the working fluid, a rotational speed of driving mechanism, a thermal environment, a targeted operation temperature and etc.. At given charging condition of helium gas, the cyclic mean pressure of helium gas in the cryocooler changes with temperatures of the cold end and the environment. In this study, effects of the cyclic mean pressure of helium gas on performances of the Stirling cryocooler were investigated by numerical analyses using the Sage software. The simulation model takes into account thermodynamic losses due to an inefficiency of regenerator, a pressure drop, a shuttle heat transfer and solid conductions. Simulations are performed for the performance variation according to the cyclic mean pressure induced by the temperature of the cold end and the environment. This paper presents P-V works in the compression and expansion space, cooling capacity, contribution of losses in the expansion space.

Effects of cyclic mean pressure of helium gas on performance of integral crank driven stirling cryocooler

International Nuclear Information System (INIS)

Hong, Yong Ju; Ko, Jun Seok; Kim, Hyo Bong; Park, Seong Je

2016-01-01

An integral crank driven Stirling cryocooler is solidly based on concepts of direct IR detector mounting on the cryocooler's cold finger, and the integral construction of the cryocooler and Dewar envelope. Performance factors of the cryocooler depend on operating conditions of the cryocooler such as a cyclic mean pressure of the working fluid, a rotational speed of driving mechanism, a thermal environment, a targeted operation temperature and etc.. At given charging condition of helium gas, the cyclic mean pressure of helium gas in the cryocooler changes with temperatures of the cold end and the environment. In this study, effects of the cyclic mean pressure of helium gas on performances of the Stirling cryocooler were investigated by numerical analyses using the Sage software. The simulation model takes into account thermodynamic losses due to an inefficiency of regenerator, a pressure drop, a shuttle heat transfer and solid conductions. Simulations are performed for the performance variation according to the cyclic mean pressure induced by the temperature of the cold end and the environment. This paper presents P-V works in the compression and expansion space, cooling capacity, contribution of losses in the expansion space

Acquisition system testing with superfluid helium

International Nuclear Information System (INIS)

Anderson, J.E.; Fester, D.A.; DiPirro, M.J.

1988-01-01

NASA is evaluating both a thermomechanical pump and centrifugal pump for the SHOOT experiment using capillary fluid acquisition systems. Tests were conducted for these systems with superfluid helium under adverse operating conditions. Minus one-g outflow tests were run in conjunction with the thermomechanical pump. Both fine mesh screen and porous sponges were tested. A screen acquisition device was also tested with the low-NPSH centrifugal pump. Results to date show that the screen and sponge are capable of supplying superfluid helium to the thermomechanical pump inlet against a one-g head up to four cm. This is more than sufficient for the SHOOT application. Results with the sponge were reproducible while those with the screen could not always be repeated

Safety in handling helium and nitrogen

International Nuclear Information System (INIS)

Schmauch, G.; Lansing, L.; Santay, T.; Nahmias, D.

1991-01-01

Based upon the authors' industrial experience and practices, they have provided an overview of safety in storage, handling, and transfer of both laboratory and bulk quantities of gaseous and liquid forms of nitrogen and helium. They have addressed the properties and characteristics of both the gaseous and liquid fluids, typical storage and transport containers, transfer techniques, and the associated hazards which include low temperatures, high pressures, and asphyxiation. Methods and procedures to control and eliminate these hazards are described, as well as risk remediation through safety awareness training, personal protective equipment, area ventilation, and atmosphere monitoring. They have included as an example a recent process hazards analysis performed by Air Products on the asphyxiation hazard associated with the use of liquid helium in MRI magnet systems

Commercial helium reserves, continental rifting and volcanism

Science.gov (United States)

Ballentine, C. J.; Barry, P. H.; Hillegonds, D.; Fontijn, K.; Bluett, J.; Abraham-James, T.; Danabalan, D.; Gluyas, J.; Brennwald, M. S.; Pluess, B.; Seneshens, D.; Sherwood Lollar, B.

2017-12-01

Helium has many industrial applications, but notably provides the unique cooling medium for superconducting magnets in medical MRI scanners and high energy beam lines. In 2013 the global supply chainfailed to meet demand causing significant concern - the `Liquid Helium Crisis' [1]. The 2017 closure of Quatar borders, a major helium supplier, is likely to further disrupt helium supply, and accentuates the urgent need to diversify supply. Helium is found in very few natural gas reservoirs that have focused 4He produced by the dispersed decay (a-particle) of U and Th in the crust. We show here, using the example of the Rukwa section of the Tanzanian East African Rift, how continental rifting and local volcanism provides the combination of processes required to generate helium reserves. The ancient continental crust provides the source of 4He. Rifting and associated magmatism provides the tectonic and thermal mechanism to mobilise deep fluid circulation, focusing flow to the near surface along major basement faults. Helium-rich springs in the Tanzanian Great Rift Valley were first identified in the 1950's[2]. The isotopic compositions and major element chemistry of the gases from springs and seeps are consistent with their release from the crystalline basement during rifting [3]. Within the Rukwa Rift Valley, helium seeps occur in the vicinity of trapping structures that have the potential to store significant reserves of helium [3]. Soil gas surveys over 6 prospective trapping structures (1m depth, n=1486) show helium anomalies in 5 out of the 6 at levels similar to those observed over a known helium-rich gas reservoir at 1200m depth (7% He - Harley Dome, Utah). Detailed macroseep gas compositions collected over two days (n=17) at one site allows us to distinguish shallow gas contributions and shows the deep gas to contain between 8-10% helium, significantly increasing resource estimates based on uncorrected values (1.8-4.2%)[2,3]. The remainder of the deep gas is

Measurement of helium production cross sections of iron for d-T neutrons by helium accumulation method

Energy Technology Data Exchange (ETDEWEB)

Takao, Yoshiyuki; Kanda, Yukinori; Nagae, Koji; Fujimoto, Toshihiro [Kyushu Univ., Fukuoka (Japan); Ikeda, Yujiro

1997-03-01

Helium production cross sections of Iron were measured by helium accumulation method for neutron energies from 13.5 to 14.9 MeV. Iron samples were irradiated with FNS, an intense d-T neutron source of JAERI. As the neutron energy varies according to the emission angle at the neutron source, the samples were set around the neutron source and were irradiated by neutrons of different energy depending on each sample position. The amount of helium produced in a sample was measured by Helium Atoms Measurement System at Kyushu University. The results of this work are in good agreement with other experimental data in the literature and also compared with the evaluated values in JENDL-3. (author)

Working memory training may increase working memory capacity but not fluid intelligence.

Science.gov (United States)

Harrison, Tyler L; Shipstead, Zach; Hicks, Kenny L; Hambrick, David Z; Redick, Thomas S; Engle, Randall W

2013-12-01

Working memory is a critical element of complex cognition, particularly under conditions of distraction and interference. Measures of working memory capacity correlate positively with many measures of real-world cognition, including fluid intelligence. There have been numerous attempts to use training procedures to increase working memory capacity and thereby performance on the real-world tasks that rely on working memory capacity. In the study reported here, we demonstrated that training on complex working memory span tasks leads to improvement on similar tasks with different materials but that such training does not generalize to measures of fluid intelligence.

Effect of replacing nitrogen with helium on a closed cycle diesel engine performance

Directory of Open Access Journals (Sweden)

Alaa M. Abo El Ela

2016-09-01

Full Text Available One of most important problems of closed cycle diesel engine is deterioration of cylinder pressure and consequently the engine power. Therefore this research aimed to establish a multi zone model using Computational Fluid Dynamic (CFD code; ANSYS Fluent 14.0 to enhance the closed cycle diesel engine performance. The present work investigates the effect of replacing nitrogen gas with helium gas in different concentration under different engine load and equivalence ratios. The numerical model results were validated with comparing them with those obtained from the previous experimental results. The engine which was used for the simulation analysis and the previous experimental work was a single cylinder with a displacement volume of 825 cm3, compression ratio of 17 and run at constant speed of 1500 RPM. The numerical results showed that replacing nitrogen with helium resulted in increasing the in-cylinder pressure. The results showed also that a percentage of 0.5–10% of helium on mass basis is sufficient in the recovery needed to overcome the drop in-cylinder pressure and hence power due to the existence of CO2 in the recycled gas up to 25%. When the CO2 % reaches 25%, it is required to use at least 10% of He as replacement gas to achieve the required recovery.

Program for aerodynamic performance tests of helium gas compressor model of the gas turbine high temperature reactor (GTHTR300)

International Nuclear Information System (INIS)

Takada, Shoji; Takizuka, Takakazu; Kunimoto, Kazuhiko; Yan, Xing; Itaka, Hidehiko; Mori, Eiji

2003-01-01

Research and development program for helium gas compressor aerodynamics was planned for the power conversion system of the Gas Turbine High Temperature Reactor (GTHTR300). The axial compressor with polytropic efficiency of 90% and surge margin more than 30% was designed with 3-dimensional aerodynamic design. Performance and surge margin of the helium gas compressor tends to be lower due to the higher boss ratio which makes the tip clearance wide relative to the blade height, as well as due to a larger number of stages. The compressor was designed on the basis of methods and data for the aerodynamic design of industrial open-cycle gas-turbine. To validate the design of the helium gas compressor of the GTHTR300, aerodynamic performance tests were planned, and a 1/3-scale, 4-stage compressor model was designed. In the tests, the performance data of the helium gas compressor model will be acquired by using helium gas as a working fluid. The maximum design pressure at the model inlet is 0.88 MPa, which allows the Reynolds number to be sufficiently high. The present study is entrusted from the Ministry of Education, Culture, Sports, Science and Technology of Japan. (author)

A sealed turbo-alternator using any working-fluid

International Nuclear Information System (INIS)

Chollet, Maurice.

1973-01-01

The invention relates to a sealed turbo-alternator operating with a working fluid other than water. The turbo-alternator and the feed and lubricating pumps thereof are housed in a sealed casing. The latter constitutes, with the heat pump and the heat sink, a sealed enclosure containing the working and lubricating fluid. The alternator, which comprises neither collector nor brushes, is dipped in the working fluid vapor. Electric energy leaves the sealed enclosure through insulating sealed passager. In view of the absence of leakage it is possible to select (e.g. among freons) a working fluid well suited to the temperature differential between the heat source and the heat sink, and, accordingly to use temperature drops which could be too small in the case of steam. The various applications are as follows: recovery of calories at the exhaust of diesels and of gas turbines or in the cooling water of diesels; equipment of isotopic generators; recovery of calories from factory waste thrown into rivers (anti-pollution effect in view of the lowering of water temperature); non-polluting engine for special electrical vehicles [fr

A reciprocating liquid helium pump used for forced flow of supercritical helium

International Nuclear Information System (INIS)

Krafft, G.; Zahn, G.

1978-01-01

The performance of a small double acting piston pump for circulating helium in a closed heat transfer loop is described. The pump was manufactured by LINDE AG, Munich, West Germany. The measured flow rate of supercritical helium was about 17 gs -1 (500 lhr -1 ) with a differential pressure of Δp = 0.5 x 10 5 Nm -2 at a working pressure of p = 6 x 10 5 Nm -2 . At differential pressures beyond 0.5 x 10 5 Nm -2 the volumetric efficiency decreases. (author)

Contribution to the study of helium two-phase vertical flow

International Nuclear Information System (INIS)

Augyrond, L.

1998-04-01

This work aims at a better understanding of the dynamics of helium two-phase flow in a vertical duct. The case of bubble flow is particularly investigated. The most descriptive parameter of two-phase flow is the void fraction. A sensor to measure this parameter was specially designed and calibrated, it is made of a radioactive source and a semiconductor detector. Sensors based on light attenuation were used to study the behaviour of this two-phase flow. The experimental set-up is described. The different flow types were photographed and video filmed. This visualization has allowed to measure the diameter of bubbles and to study their movements in the fluid. Bubble flow then churn and annular flows were observed but slug flow seems not to exist with helium. A modelling based on a Zuber model matches better the experimental results than a Levy type model. The detailed analysis of the signals given by the optical sensors has allowed to highlight a bubble appearance frequency directly linked to the flowrate. (A.C.)

Helium 3 precipitation in AISI 316L stainless steel induced by radioactive decay of tritium: Microstructural study of helium bubble precipitation

International Nuclear Information System (INIS)

Brass, A.M.; Chene, J.

1994-01-01

The development of the thermonuclear technology has given rise to a renewed interest in the study of the behavior of helium in metals. A great amount of work is still required for the understanding of the role of helium on the mechanical properties of structural materials for fusion technology, especially austenitic stainless steels. This article deals with the study of the influence of thermomechanical heat treatments, aging conditions (temperature and time), and helium concentration of helium bubble precipitation in a 316L austenitic steel. Helium was generated by the radioactive decay of tritium (tritium trick). Helium bubbles impede the grain growth in 316L steel aged at 1,373 K and also the recrystallization reaction at this temperature if cold working is performed prior to aging. Transmission electron microscopy (TEM) observations indicated a weak helium precipitation at 1,073 and 1,223 K, presumably due to the presence of trapping sites for tritium, and no bubble growth after aging up to 100 hours. Precipitation sites are mainly dislocations in the matrix at 1,073 K and grain boundaries and individual dislocations in the matrix at 1,223 K. The large bubble size (50 nm) observed at 1,373 K, even for short aging times (0.083), can partly be attributed to bubble dragging by dislocations toward the grain boundaries. Cold deformation prior to aging leads to a larger bubble size due to growth enhancement during recrystallization. Decreasing the helium content leads to a smaller helium bubble size and density. Tritium trapping at helium bubbles may favor helium 3 accumulation on defects such as grain boundaries, as observed by tritium autoradiography

European standardization activities on safety of liquid helium cryostats

CERN Multimedia

CERN. Geneva

2016-01-01

This talk gives a general overview on the challenges of designing safety units for liquid helium cryostats with regard to existing industry standards. It reviews the work of a national working group that published the technical guideline DIN SPEC 4683 in April 2015, which is dedicated to the particular conditions in liquid helium cryostats. Based on both this guideline and equivalent documents from e.g. CEA, CERN, a working group is being formed at the European Committee for Standardization, associated to CEN/TC 268, which will work on a European standard on safety of liquid helium cryostats. The actual status and the schedule of this project are presented.

Helium production in mixed spectrum reactor-irradiated pure elements

International Nuclear Information System (INIS)

Kneff, D.W.; Oliver, B.M.; Skowronski, R.P.

1986-01-01

The objectives of this work are to apply helium accumulation neutron dosimetry to the measurement of neutron fluences and energy spectra in mixed-spectrum fission reactors utilized for fusion materials testing, and to measure helium generation rates of materials in these irradiation environments. Helium generation measurements have been made for several Fe, Cu Ti, Nb, Cr, and Pt samples irradiated in the mixed-spectrum High Flux Isotope Reactor (HFIR) and Oak Ridge Research Reactor (ORR) at the Oak Ridge National Laboratory. The results have been used to integrally test the ENDF/B-V Gas Production File, by comparing the measurements with helium generation predictions made by Argonne National Laboratory using ENDF/B-V cross sections and adjusted reactor spectra. The comparisons indicate consistency between the helium measurements and ENDF/B-V for iron, but cross section discrepancies exist for helium production by fast neutrons in Cu, Ti, Nb, and Cr (the latter for ORR). The Fe, Cu, and Ti work updates and extends previous measurements

Optomechanics in a Levitated Droplet of Superfluid Helium

Science.gov (United States)

Brown, Charles; Harris, Glen; Harris, Jack

2017-04-01

A critical issue common to all optomechanical systems is dissipative coupling to the environment, which limits the system's quantum coherence. Superfluid helium's extremely low optical and mechanical dissipation, as well as its high thermal conductivity and its ability cool itself via evaporation, makes the mostly uncharted territory of superfluid optomechanics an exciting avenue for exploring quantum effects in macroscopic objects. I will describe ongoing work that aims to exploit the unique properties of superfluid helium by constructing an optomechanical system consisting of a magnetically levitated droplet of superfluid helium., The optical whispering gallery modes (WGMs) of the droplet, as well as the mechanical oscillations of its surface, should offer exceptionally low dissipation, and should couple to each other via the usual optomechanical interactions. I will present recent progress towards this goal, and also discuss the background for this work, which includes prior demonstrations of magnetic levitation of superfluid helium, high finesse WGMs in liquid drops, and the self-cooling of helium drops in vacuum.

The thermodynamic properties of normal liquid helium 3

Science.gov (United States)

Modarres, M.; Moshfegh, H. R.

2009-09-01

The thermodynamic properties of normal liquid helium 3 are calculated by using the lowest order constrained variational (LOCV) method. The Landau Fermi liquid model and Fermi-Dirac distribution function are considered as our statistical model for the uncorrelated quantum fluid picture and the Lennard-Jones and Aziz potentials are used in our truncated cluster expansion (LOCV) to calculate the correlated energy. The single particle energy is treated variationally through an effective mass. The free energy, pressure, entropy, chemical potential and liquid phase diagram as well as the helium 3 specific heat are evaluated, discussed and compared with the corresponding available experimental data. It is found that the critical temperature for the existence of the pure gas phase is about 4.90 K (4.45 K), which is higher than the experimental prediction of 3.3 K, and the helium 3 flashing temperature is around 0.61 K (0.50 K) for the Lennard-Jones (Aziz) potential.

Behaviour of helium after implantation in molybdenum

International Nuclear Information System (INIS)

Viaud, C.; Maillard, S.; Carlot, G.; Valot, C.; Gilabert, E.; Sauvage, T.; Peaucelle, C.; Moncoffre, N.

2009-01-01

This study deals with the behaviour of helium in a molybdenum liner dedicated to the retention of fission products. More precisely this work contributes to evaluate the release of implanted helium when the gas has precipitated into nanometric bubbles close to the free surface. A simple model dedicated to calculate the helium release in such a condition is presented. The specificity of this model lays on the assumption that the gas is in equilibrium with a simple distribution of growing bubbles. This effort is encouraging since the calculated helium release fits an experimental dataset with a set of parameters in good agreement with the literature

Investigation of helium-induced embrittlement

International Nuclear Information System (INIS)

Sabelova, V.; Slugen, V.; Krsjak, V.

2014-01-01

In this work, the hardness of Fe-9%(wt.) Cr binary alloy implanted by helium ions up to 1000 nm was investigated. The implantations were performed using linear accelerator at temperatures below 80 grad C. Isochronal annealing up to 700 grad C with the step of 100 grad C was applied on the helium implanted samples in order to investigate helium induced embrittlement of material. Obtained results were compared with theoretical calculations of dpa profiles. Due to the results, the nano-hardness technique results to be an appropriate approach to the hardness determination of thin layers of implanted alloys. Both, experimental and theoretical calculation techniques (SRIM) show significant correlation of measured results of induced defects. (authors)

Absolute measurement of the viscosity of classical and quantum fluids by rotating-cylinder viscometers

International Nuclear Information System (INIS)

Donnelly, R.J.; LaMar, M.M.

1987-01-01

We discuss the use of rotating-cylinder viscometers to determine absolute shear viscosities of classical fluids and of helium II in the context of past and current knowledge of the stability and flow of these fluids between concentric cylinders. We identify a problem in measuring the absolute viscosity when the inner cylinder is rotating and the outer cylinder is at rest. We conclude by discussing the design of viscometers for absolute viscosity measurements in helium I and helium II

Thermodynamics of Fluid Polyamorphism

Directory of Open Access Journals (Sweden)

Mikhail A. Anisimov

2018-01-01

Full Text Available Fluid polyamorphism is the existence of different condensed amorphous states in a single-component fluid. It is either found or predicted, usually at extreme conditions, for a broad group of very different substances, including helium, carbon, silicon, phosphorous, sulfur, tellurium, cerium, hydrogen, and tin tetraiodide. This phenomenon is also hypothesized for metastable and deeply supercooled water, presumably located a few degrees below the experimental limit of homogeneous ice formation. We present a generic phenomenological approach to describe polyamorphism in a single-component fluid, which is completely independent of the molecular origin of the phenomenon. We show that fluid polyamorphism may occur either in the presence or in the absence of fluid phase separation depending on the symmetry of the order parameter. In the latter case, it is associated with a second-order transition, such as in liquid helium or liquid sulfur. To specify the phenomenology, we consider a fluid with thermodynamic equilibrium between two distinct interconvertible states or molecular structures. A fundamental signature of this concept is the identification of the equilibrium fraction of molecules involved in each of these alternative states. However, the existence of the alternative structures may result in polyamorphic fluid phase separation only if mixing of these structures is not ideal. The two-state thermodynamics unifies all the debated scenarios of fluid polyamorphism in different areas of condensed-matter physics, with or without phase separation, and even goes beyond the phenomenon of polyamorphism by generically describing the anomalous properties of fluids exhibiting interconversion of alternative molecular states.

Compression in Working Memory and Its Relationship With Fluid Intelligence.

Science.gov (United States)

Chekaf, Mustapha; Gauvrit, Nicolas; Guida, Alessandro; Mathy, Fabien

2018-06-01

Working memory has been shown to be strongly related to fluid intelligence; however, our goal is to shed further light on the process of information compression in working memory as a determining factor of fluid intelligence. Our main hypothesis was that compression in working memory is an excellent indicator for studying the relationship between working-memory capacity and fluid intelligence because both depend on the optimization of storage capacity. Compressibility of memoranda was estimated using an algorithmic complexity metric. The results showed that compressibility can be used to predict working-memory performance and that fluid intelligence is well predicted by the ability to compress information. We conclude that the ability to compress information in working memory is the reason why both manipulation and retention of information are linked to intelligence. This result offers a new concept of intelligence based on the idea that compression and intelligence are equivalent problems. Copyright © 2018 Cognitive Science Society, Inc.

Theoretical aspects concerning working fluids in hydraulic systems

Directory of Open Access Journals (Sweden)

Tița Irina

2017-01-01

Full Text Available Among the properties of working fluid, viscosity is the most important as it regards especially to pumps. In order to study the behavior of hydrostatic transmission it is important to create a reliable research instrument for dynamic simulation. Our research expertise being in SimHydraulics consequently this instrument is the suitable block diagram. The purpose of this paper is to present the possible ways to customize the properties of the working fluid in the block diagram.

Natural working fluids for solar-boosted heat pumps

Energy Technology Data Exchange (ETDEWEB)

Chaichana, C.; Lu Aye [University of Melbourne, Victoria (Australia). International Technologies Centre, Department of Civil and Environmental Engineering; Charters, W.W.S. [University of Melbourne, Victoria (Australia). Department of Mechanical and Manufacturing Engineering

2003-09-01

The option of using natural working fluids as a substitute of R-22 for solar-boosted heat pumps depends not only upon thermal performance and hazardous rating but also on potential impacts on the environment. This paper presents the comparative assessment of natural working fluids with R-22 in terms of their characteristics and thermophysical properties, and thermal performance. Some justification is given for using natural working fluids in a solar boosted heat pump water heater. The results show that R-744 is not suitable for solar-boosted heat pumps because of its low critical temperature and high operational pressures. On the other hand, R-717 seems to be a more appropriate substitute in terms of operational parameters and overall performance. However, major changes in the heat pumps are required. R-290 and R-1270 are identified as candidates for direct drop-in substitutes for R-22. (author)

Helium-air exchange flows through partitioned opening and two-opening

International Nuclear Information System (INIS)

Kang, T. I.

1997-01-01

This paper describes experimental investigations of helium-air exchange flows through partitioned opening and two-opening. Such exchange flows may occur following rupture accident of stand pipe in high temperature engineering test reactor. A test vessel with the two types of small opening on top of test cylinder is used for experiments. An estimation method of mass increment is developed to measure the exchange flow rate. Upward flow of the helium and downward flow of the air in partitioned opening system interact out of entrance and exit of the opening. Therefore, an experiment with two-opening system is made to investigate effect of the fluids interaction of partitioned opening system. As a result of comparison of the exchange flow rates between two types of the opening system, it is demonstrated that the exchange flow rate of the two-opening system is larger than that of the partitioned opening system because of absence of the effect of fluids interaction. (author)

Simplified Methodology to Estimate the Maximum Liquid Helium (LHe) Cryostat Pressure from a Vacuum Jacket Failure

Science.gov (United States)

Ungar, Eugene K.; Richards, W. Lance

2015-01-01

tool, final verification of the dewar pressure vessel design requires a complete, detailed real fluid compressible flow model of the vent stack. The wall heat flux resulting from a loss of vacuum insulation increases the dewar pressure, which actuates the pressure relief mechanism and results in high-speed flow through the dewar vent stack. At high pressures, the flow can be choked at the vent stack inlet, at the exit, or at an intermediate transition or restriction. During previous SOFIA analyses, it was observed that there was generally a readily identifiable section of the vent stack that would limit the flow – e.g., a small diameter entrance or an orifice. It was also found that when the supercritical helium was approximated as an ideal gas at the dewar condition, the calculated mass flow rate based on choking at the limiting entrance or transition was less than the mass flow rate calculated using the detailed real fluid model2. Using this lower mass flow rate would yield a conservative prediction of the dewar’s wall heat flux capability. The simplified method of the current work was developed by building on this observation.

Pressurized helium II-cooled magnet test facility

International Nuclear Information System (INIS)

Warren, R.P.; Lambertson, G.R.; Gilbert, W.S.; Meuser, R.B.; Caspi, S.; Schafer, R.V.

1980-06-01

A facility for testing superconducting magnets in a pressurized bath of helium II has been constructed and operated. The cryostat accepts magnets up to 0.32 m diameter and 1.32 m length with current to 3000 A. In initial tests, the volume of helium II surrounding the superconducting magnet was 90 liters. Minimum temperature reached was 1.7 K at which point the pumping system was throttled to maintain steady temperature. Helium II reservoir temperatures were easily controlled as long as the temperature upstream of the JT valve remained above T lambda; at lower temperatures control became difficult. Positive control of the temperature difference between the liquid and cold sink by means of an internal heat source appears necessary to avoid this problem. The epoxy-sealed vessel closures, with which we have had considerable experience with normal helium vacuum, also worked well in the helium II/vacuum environment

Evaluation of Working Fluids for Organic Rankine Cycle Based on Exergy Analysis

Science.gov (United States)

Setiawan, D.; Subrata, I. D. M.; Purwanto, Y. A.; Tambunan, A. H.

2018-05-01

One of the crucial aspects to determine the performance of Organic Rankine Cycle (ORC) is the selection of appropriate working fluids. This paper describes the simulative performance of several organic fluid and water as working fluid of an ORC based on exergy analysis with a heat source from waste heat recovery. The simulation was conducted by using Engineering Equation Solver (EES). The effect of several parameters and thermodynamic properties of working fluid was analyzed, and part of them was used as variables for the simulation in order to determine their sensitivity to the exergy efficiency changes. The results of this study showed that water is not appropriate to be used as working fluid at temperature lower than 130 °C, because the expansion process falls in saturated area. It was also found that Benzene had the highest exergy efficiency, i.e. about 10.49%, among the dry type working fluid. The increasing turbine inlet temperature did not lead to the increase of exergy efficiency when using organic working fluids with critical temperature near heat source temperature. Meanwhile, exergy efficiency decreasing linearly with the increasing condenser inlet temperature. In addition, it was found that working fluid with high latent heat of vaporization and specific heat exert in high exergy efficiency.

The use of cryogenic helium for classical turbulence: Promises and hurdles

International Nuclear Information System (INIS)

Niemela, J.J.; Sreenivasan, K.R.

2006-12-01

Fluid turbulence is a paradigm for non-linear systems with many degrees of freedom and important in numerous applications. Because the analytical understanding of the equations of motion is poor, experiments and, lately, direct numerical simulations of the equations of motion, have been fundamental to making progress. In this vein, a concerted experimental effort has been made to take advantage of the unique properties of liquid and gaseous helium at low temperatures near or below the critical point. We discuss the promise and impact of results from recent helium experiments and identify the current technical barriers which can perhaps be removed by low temperature researchers. We focus mainly on classical flows that utilize helium above the lambda line, but touch on those aspects below that exhibit quasi-classical behavior. (author)

Thermophysical Properties of Aqueous Solutions Used as Secondary Working Fluids

OpenAIRE

Melinder, Åke

2007-01-01

Secondary working fluids (secondary refrigerants, heat transfer fluids, antifreezes, brines) have long been used in various indirect re-frigeration and heat pump systems. Aqueous solutions (water solu-tions) have long been used as single phase (liquid only) secondary working fluids for cooling in supermarkets, ice rinks, heat recovery systems, heat pumps and other applications. However, aqueous solutions are increasingly used also for freezers in supermarkets and other applications in low tem...

Combined measurements on stationary flow of helium II

International Nuclear Information System (INIS)

Ijsselstein, R.R.

1979-01-01

Transport phenomena in helium II can in principle be described by a two fluid model. One of the fluids, the superfluid component, carries no entropy and has no viscosity while its velocity field is curl free. The other, the normal component, behaves like an ordinary fluid and carries the entropy of the whole liquid. In measuring flow two different methods are required because of the two independent velocity fields. This thesis describes an experiment where both techniques are applied to flow through a capillary of 0.62 mm, enabling direct comparison. The apparatus is described, and details of the measuring techniques are reported. An extended treatment of second-sound phenomena in a Helmholtz resonator is given. The results of the measurements are reported and discussed. (Auth.)

Working Fluid Stability in Large-Scale Organic Rankine Cycle-Units Using Siloxanes—Long-Term Experiences and Fluid Recycling

Directory of Open Access Journals (Sweden)

Tobias G. Erhart

2016-05-01

Full Text Available The results in this work show the influence of long-term operation on the decomposition of working fluids in eight different organic rankine cycle (ORC power plants (both heat-led and electricity-led in a range of 900 kW el to 2 MW el . All case study plants are using octamethyltrisiloxane (MDM as a working fluid; the facilities are between six to 12 years old. Detailed analyses, including the fluid distribution throughout the cycle, are conducted on one system. All presented fluid samples are analyzed via head space gas chromatography mass spectrometry (HS-GC-MS. Besides the siloxane composition, the influence of contaminants, such as mineral oil-based lubricants (and their components, is examined. In most cases, the original working fluid degrades to fractions of siloxanes with a lower boiling point (low boilers and fractions with a higher boiling point (high boilers. As a consequence of the analyses, a new fluid recycling and management system was designed and tested in one case study plant (Case Study #8. Pre-post comparisons of fluid samples prove the effectiveness of the applied methods. The results show that the recovery of used working fluid offers an alternative to the purchase of fresh fluid, since operating costs can be significantly reduced. For large facilities, the prices for new fluid range from € 15 per liter (in 2006 to € 22 per liter (in 2013, which is a large reinvestment, especially in light of filling volumes of 4000 liters to 7000 liters per unit. Using the aforementioned method, a price of € 8 per liter of recovered MDM can be achieved.

Online helium inventory monitoring of JLab cryogenic systems

Science.gov (United States)

Hasan, N.; Knudsen, P.; Wright, M.

2017-12-01

There are five cryogenic plants at Jefferson Lab which support the LINAC, experiment hall end-stations and test facility. The majority of JLab’s helium inventory, which is around 15 tons, is allocated in the LINAC cryo-modules, with the majority of the balance of helium distributed at the cryogenic-plant level mainly as stored gas and liquid for stable operation. Due to the organic evolution of the five plants and independent actions within the experiment halls, the traditional inventory management strategy suffers from rapid identification of potential leaks. This can easily result in losses many times higher than the normally accepted (average) loss rate. A real-time program to quickly identify potential excessive leakage was developed and tested. This program was written in MATLAB© for portability, easy diagnostics and modification. It interfaces directly with EPICS to access the cryogenic system state, and with and NIST REFPROP© for real fluid properties. This program was validated against the actual helium offloaded into the system. The present paper outlines the details of the inventory monitoring program, its validation and a sample of the achieved results.

Growth process of helium bubbles in aluminium

International Nuclear Information System (INIS)

Shiraishi, Haruki; Sakairi, Hideo; Yagi, Eiichi; Karasawa, Takashi; Hashiguti, R.R.

1975-01-01

The growth process of helium bubbles in α-particle bombarded pure aluminum during isothermal anneal ranging 200 to 645 0 C and 1 to 100 hr was observed by a transmission electron microscope and the possible growth mechanisms are discussed. The effects of helium concentration and cold work were investigated. The helium bubbles are detectable only at the anneal above 550 0 C in both annealed and cold worked samples. The cold work does not cause any extra coarsening trend of bubbles. The observed types of bubble distribution in the grain interior are divided into two categories, irrespective of helium concentration and cold work; (1) the fine and uniform bubble distribution, in which case the average size is limited to about 200 A or less in diameter even at the anneal just below the melting point, and (2) the coarsened and non-uniform bubble distribution ranging 500 to 4000 A in diameter. The intermediate size bubbles are scarcely found in any cases. In the above fine bubble distribution, the increase of helium concentration by a factor of two increases the density by the same factor of two, but does not change the mean size of bubbles. Corresponding to the above two characteristic bubble distributions, it is concluded that two different mechanisms are operative in this experiment; (1) the growth of bubbles by the Brownian motion, in which the growth rate of bubbles is decreased to almost zero by bubble faceting and this results in the bubble size constancy during the prolonged annealing, and (2) the growth of bubbles by the grain boundary sweep-out mechanism, by which the abrupt coarsening of bubbles is caused. The lack of existence of the intermediate size bubbles is explained in this way. (auth.)

A helium based pulsating heat pipe for superconducting magnets

Science.gov (United States)

Fonseca, Luis Diego; Miller, Franklin; Pfotenhauer, John

2014-01-01

This study was inspired to investigate an alternative cooling system using a helium-based pulsating heat pipes (PHP), for low temperature superconducting magnets. In addition, the same approach can be used for exploring other low temperature applications. The advantages of PHP for transferring heat and smoothing temperature profiles in various room temperature applications have been explored for the past 20 years. An experimental apparatus has been designed, fabricated and operated and is primarily composed of an evaporator and a condenser; in which both are thermally connected by a closed loop capillary tubing. The main goal is to measure the heat transfer properties of this device using helium as the working fluid. The evaporator end of the PHP is comprised of a copper winding in which heat loads up to 10 watts are generated, while the condenser is isothermal and can reach 4.2 K via a two stage Sumitomo RDK408A2 GM cryocooler. Various experimental design features are highlighted. Additionally, performance results in the form of heat transfer and temperature characteristics are provided as a function of average condenser temperature, PHP fill ratio, and evaporator heat load. Results are summarized in the form of a dimensionless correlation and compared to room temperature systems. Implications for superconducting magnet stability are highlighted.

Quantitative mass-spectrometric analysis of hydrogen helium isotope mixtures

International Nuclear Information System (INIS)

Langer, U.

1998-12-01

This work deals with the mass-spectrometric method for the quantitative analysis of hydrogen-helium-isotope mixtures, with special attention to fusion plasma diagnostics. The aim was to use the low-resolution mass spectrometry, a standard measuring method which is well established in science and industry. This task is solved by means of the vector mass spectrometry, where a mass spectrum is repeatedly measured, but with stepwise variation of the parameter settings of a quadruple mass spectrometer. In this way, interfering mass spectra can be decomposed and, moreover, it is possible to analyze underestimated mass spectra of complex hydrogen-helium-isotope mixtures. In this work experimental investigations are presented which show that there are different parameters which are suitable for the UMS-method. With an optimal choice of the parameter settings hydrogen-helium-isotope mixtures can be analyzed with an accuracy of 1-3 %. In practice, a low sensitivity for small helium concentration has to be noted. To cope with this task, a method for selective hydrogen pressure reduction has been developed. Experimental investigations and calculations show that small helium amounts (about 1 %) in a hydrogen atmosphere can be analyzed with an accuracy of 3 - 10 %. Finally, this work deals with the effects of the measuring and calibration error on the resulting error in spectrum decomposition. This aspect has been investigated both in general mass-spectrometric gas analysis and in the analysis of hydrogen-helium-mixtures by means of the vector mass spectrometry. (author)

Two-fluid hydrodynamic modes in a trapped superfluid gas

International Nuclear Information System (INIS)

Taylor, E.; Griffin, A.

2005-01-01

In the collisional region at finite temperatures, the collective modes of superfluids are described by the Landau two-fluid hydrodynamic equations. This region can now be probed over the entire BCS-Bose-Einstein-condensate crossover in trapped Fermi superfluids with a Feshbach resonance, including the unitarity region. Building on the approach initiated by Zaremba, Nikuni, and Griffin in 1999 for trapped atomic Bose gases, we present a variational formulation of two-fluid hydrodynamic collective modes based on the work of Zilsel in 1950 developed for superfluid helium. Assuming a simple variational Ansatz for the superfluid and normal fluid velocities, the frequencies of the hydrodynamic modes are given by solutions of coupled algebraic equations, with constants only involving spatial integrals over various equilibrium thermodynamic derivatives. This variational approach is both simpler and more physical than a direct attempt to solve the Landau two-fluid differential equations. Our two-fluid results are shown to reduce to those of Pitaevskii and Stringari for a pure superfluid at T=0

Magic angle spinning NMR below 6 K with a computational fluid dynamics analysis of fluid flow and temperature gradients

Science.gov (United States)

Sesti, Erika L.; Alaniva, Nicholas; Rand, Peter W.; Choi, Eric J.; Albert, Brice J.; Saliba, Edward P.; Scott, Faith J.; Barnes, Alexander B.

2018-01-01

We report magic angle spinning (MAS) up to 8.5 kHz with a sample temperature below 6 K using liquid helium as a variable temperature fluid. Cross polarization 13C NMR spectra exhibit exquisite sensitivity with a single transient. Remarkably, 1H saturation recovery experiments show a 1H T1 of 21 s with MAS below 6 K in the presence of trityl radicals in a glassy matrix. Leveraging the thermal spin polarization available at 4.2 K versus 298 K should result in 71 times higher signal intensity. Taking the 1H longitudinal relaxation into account, signal averaging times are therefore predicted to be expedited by a factor of >500. Computer assisted design (CAD) and finite element analysis were employed in both the design and diagnostic stages of this cryogenic MAS technology development. Computational fluid dynamics (CFD) models describing temperature gradients and fluid flow are presented. The CFD models bearing and drive gas maintained at 100 K, while a colder helium variable temperature fluid stream cools the center of a zirconia rotor. Results from the CFD were used to optimize the helium exhaust path and determine the sample temperature. This novel cryogenic experimental platform will be integrated with pulsed dynamic nuclear polarization and electron decoupling to interrogate biomolecular structure within intact human cells.

Performance analysis of organic Rankine cycles using different working fluids

Directory of Open Access Journals (Sweden)

Zhu Qidi

2015-01-01

Full Text Available Low-grade heat from renewable or waste energy sources can be effectively recovered to generate power by an organic Rankine cycle (ORC in which the working fluid has an important impact on its performance. The thermodynamic processes of ORCs using different types of organic fluids were analyzed in this paper. The relationships between the ORC’s performance parameters (including evaporation pressure, condensing pressure, outlet temperature of hot fluid, net power, thermal efficiency, exergy efficiency, total cycle irreversible loss, and total heat-recovery efficiency and the critical temperatures of organic fluids were established based on the property of the hot fluid through the evaporator in a specific working condition, and then were verified at varied evaporation temperatures and inlet temperatures of the hot fluid. Here we find that the performance parameters vary monotonically with the critical temperatures of organic fluids. The values of the performance parameters of the ORC using wet fluids are distributed more dispersedly with the critical temperatures, compared with those of using dry/isentropic fluids. The inlet temperature of the hot fluid affects the relative distribution of the exergy efficiency, whereas the evaporation temperature only has an impact on the performance parameters using wet fluid.

Molecular Entropy, Thermal Efficiency, and Designing of Working Fluids for Organic Rankine Cycles

Science.gov (United States)

Wang, Jingtao; Zhang, Jin; Chen, Zhiyou

2012-06-01

A shortage of fossil energy sources boosts the utilization of renewable energy. Among numerous novel techniques, recovering energy from low-grade heat sources through power generation via organic Rankine cycles (ORCs) is one of the focuses. Properties of working fluids are crucial for the ORC's performance. Many studies have been done to select proper working fluids or to design new working fluids. However, no researcher has systematically investigated the relationship between molecular structures and thermal efficiencies of various working fluids for an ideal ORC. This paper has investigated the interrelations of molecular structures, molecular entropies, and thermal efficiencies of various working fluids for an ideal ORC. By calculating thermal efficiencies and molecular entropies, we find that the molecular entropy is the most appropriate thermophysical property of a working fluid to determine how much energy can be converted into work and how much cannot in a system. Generally speaking, working fluids with low entropies will generally have high thermal efficiency for an ideal ORC. Based on this understanding, the direct interrelations of molecular structures and entropies provide an explicit interrelation between molecular structures and thermal efficiencies, and thus provide an insightful direction for molecular design of novel working fluids for ORCs.

Experimental Characterization of Cryogenic Helium Pulsating Heat Pipes

Science.gov (United States)

Fonseca Flores, Luis Diego

This study was inspired to investigate an alternative cooling system using a helium-based pulsating heat pipes (PHP), for low temperature superconducting magnets in MRI systems. In addition, the same approach can be used for exploring other low temperature applications such as cooling space instrumentation. The advantages of PHP for transferring heat and smoothing temperature profiles in various room temperature applications have been explored for the past 20 years. An experimental apparatus has been designed, fabricated and operated and is primarily composed of an evaporator and a condenser; in which both are thermally connected by a closed loop capillary tubing. The main goal is to measure the heat transfer properties of this device using helium as the working fluid. The evaporator end of the PHP is comprised of a copper winding in which heat loads up to 10 watts are generated, while the condenser is isothermal and can reach 4.2 K at 1 W via a two stage Sumitomo RDK408A2 GM cryocooler. Various experimental design features are highlighted. Additionally, the thermal performance for the presented design remained unchanged when increasing the adiabatic length from 300 mm to 1000 mm. Finally a spring mass damper model has been developed and proven to predict well the experimental data, such models should be used as tool to design and manufacturer PHP prototypes.

Tables of thermodynamic properties of helium magnet coolant

International Nuclear Information System (INIS)

McAshan, M.

1992-07-01

The most complete treatment of the thermodynamic properties of helium at the present time is the monograph by McCarty: ''Thermodynamic Properties of Helium 4 from 2 to 1500 K at Pressures to 10 8 Pa'', Robert D. McCarty, Journal of Physical and Chemical Reference Data, Vol. 2, page 923--1040 (1973). In this work the complete range of data on helium is examined and the P-V-T surface is described by an equation of state consisting of three functions P(r,T) covering different regions together with rules for making the transition from one region to another. From this thermodynamic compilation together with correlations of the transport properties of helium was published the well-known NBS Technical Note: ''Thermophysical Properties of Helium 4 from 2 to 1500 K with pressures to 1000 Atmospheres'', Robert D. McCarty, US Department of Commerce, National Bureau of Standards Technical Note 631 (1972). This is the standard reference for helium cryogenics. The NBS 631 tables cover a wide range of temperature and pressure, and as a consequence, the number of points tabulated in the region of the single phase coolant for the SSC magnets are relatively few. The present work sets out to cover the range of interest in more detail in a way that is consistent with NBS 631. This new table is essentially identical to the older one and can be used as an auxiliary to it

New era for CO2 as a working fluid

International Nuclear Information System (INIS)

Stene, Joern

2000-01-01

During the past decade there has been extensive international activity to find acceptable alternatives to ozone-depleting CFC and HCFC substances that have been widely used as working fluids in refrigerating and heat pump plants. At present, the so-called natural working fluids constitute the most environmentally friendly alternative, and they include first of all ammonia, hydrocarbons and carbon dioxide (CO2). NTNU and SINTEF Energy Research, Norway, have been pioneers in the development of refrigerating and heat pump systems that use CO2 as a working fluid. The favourable technical and environmental properties of CO2 as well as the promising results have now led to considerable international interest in CO2 technology for refrigerating and heat pump applications. Two examples are international licensing for Norwegian CO2 technology and co-operation with Indonesia on CO2 for refrigeration

Design analysis of a Helium re-condenser

Science.gov (United States)

Muley, P. K.; Bapat, S. L.; Atrey, M. D.

2017-02-01

Modern helium cryostats deploy a cryocooler with a re-condenser at its II stage for in-situ re-condensation of boil-off vapor. The present work is a vital step in the ongoing research work of design of cryocooler based 100 litre helium cryostat with in-situ re-condensation. The cryostat incorporates a two stage Gifford McMahon cryocooler having specified refrigerating capacity of 40 W at 43 K for I stage and 1 W at 4.2 K for II stage. Although design of cryostat ensures thermal load for cryocooler below its specified refrigerating capacity at the second stage, successful in-situ re-condensation depends on proper design of re-condenser which forms the objective of this work. The present work proposes design of helium re-condenser with straight rectangular fins. Fins are analyzed for optimization of thermal performance parameters such as condensation heat transfer coefficient, surface area for heat transfer, re-condensing capacity, efficiency and effectiveness. The present work provides design of re-condenser with 19 integral fins each of 10 mm height and 1.5 mm thickness with a gap of 1.5 mm between two fins, keeping in mind the manufacturing feasibility, having efficiency of 80.96 % and effectiveness of 10.34.

Cryogenic filter method produces super-pure helium and helium isotopes

Science.gov (United States)

Hildebrandt, A. F.

1964-01-01

Helium is purified when cooled in a low pressure environment until it becomes superfluid. The liquid helium is then filtered through iron oxide particles. Heating, cooling and filtering processes continue until the purified liquid helium is heated to a gas.

High temperature tensile properties of 316 stainless steel implanted with helium

International Nuclear Information System (INIS)

Hasegawa, Akira; Yamamoto, Norikazu; Shiraishi, Haruki

1993-01-01

Helium embrittlement is one of the problems in structural materials for fusion reactors. Recently, martensitic steels have been developed which have a good resistance to high-temperature helium embrittlement, but the mechanism has not yet been clarified. In this paper, tensile behaviors of helium implanted austenitic stainless steels, which are sensitive to the helium embrittlement, were studied and compared with those of martensitic steels under the same experimental conditions, and the effect of microstructure on helium embrittlement was discussed. Helium was implanted by 300 appm at 573-623 K to miniature tensile speciments of 316 austenitic steels using a cyclotron accelerator. Solution annealed (316SA) and 20% cold worked (316CW) specimens were used. Post-implantation tensile tests were carried out at 573, 873 and 973 K. Yield stress at 573 K increased with the helium implantation in 316SA and 316CW, but the yield stress changes of 316SA at 873 and 973 K were different from that of 316CW. Black-dots were observed in the as-implanted specimen and bubbles were observed in the speciments tensile-tested at 873 and 973 K. Intergranular fracture was observed at only 973 K in both of the 316SA and 316CW specimens. Therefore, cold work did not suppress the high-temperature helium embrittlement under this experimental condition. The difference in the influence of helium on type 316 steel and 9Cr martensitic steels were discussed. Test temperature change of reduction in are showed clearly that helium embrittlement did not occur in 9Cr martensitic steels but occurred in 316 austenitic steels. Fine microstructures of 9Cr martensitic steels should suppress helium embrittlement at high temperatures. (author)

The high-temperature helium test facility (HHV)

International Nuclear Information System (INIS)

Noack, G.; Weiskopf, H.

1977-03-01

The report describes the high-temperature helium test facility (HHV). Construction of this plant was started in 1972 by Messrs. BBC, Mannheim, on behalf of the Kernforschungsanlage Juelich. By the end of 1976, the construction work is in its last stage, so that the plant may start operation early in 1977. First of all, the cycle system and the arrangement of components are dealt with, followed by a discussion of individual components. Here, emphasis is laid on components typical for HHT systems, while conventional components are mentioned without further structural detail. The projected test programme for the HHV facility in phase IB of the HHT project is shortly dealt with. After this, the potential of this test facility with regard to the possible use of test components and to fluid- and thermodynamic boundary conditions is pointed out. With the unique potential the facility offers here, aspects of shortened service life at higher cycle temperatures do not remain disregarded. (orig./UA) [de

Effects of helium impurities on superalloys

International Nuclear Information System (INIS)

Selle, J.E.

1977-07-01

A review of the literature on the effects of helium impurities on superalloys at elevated temperatures was undertaken. The actual effects of these impurities vary depending on the alloy, composition of the gas atmosphere, and temperature. In general, exposure in helium produces significant but not catastrophic changes in the structure and properties of the alloys. The effects of these treatments on the structure, creep, fatigue, and mechanical properties of the various alloys are reviewed and discussed. Suggestions for future work are presented

Working Memory Capacity and Fluid Intelligence: Maintenance and Disengagement.

Science.gov (United States)

Shipstead, Zach; Harrison, Tyler L; Engle, Randall W

2016-11-01

Working memory capacity and fluid intelligence have been demonstrated to be strongly correlated traits. Typically, high working memory capacity is believed to facilitate reasoning through accurate maintenance of relevant information. In this article, we present a proposal reframing this issue, such that tests of working memory capacity and fluid intelligence are seen as measuring complementary processes that facilitate complex cognition. Respectively, these are the ability to maintain access to critical information and the ability to disengage from or block outdated information. In the realm of problem solving, high working memory capacity allows a person to represent and maintain a problem accurately and stably, so that hypothesis testing can be conducted. However, as hypotheses are disproven or become untenable, disengaging from outdated problem solving attempts becomes important so that new hypotheses can be generated and tested. From this perspective, the strong correlation between working memory capacity and fluid intelligence is due not to one ability having a causal influence on the other but to separate attention-demanding mental functions that can be contrary to one another but are organized around top-down processing goals. © The Author(s) 2016.

Interdiffusion of krypton and xenon in high-pressure helium

International Nuclear Information System (INIS)

Campana, R.J.; Jensen, D.D.; Epstein, B.D.; Hudson, R.G.; Baldwin, N.L.

1980-01-01

The interdiffusion of gaseous fission products in high-pressure helium is an important factor in the control of radioactivity in gas-cooled fast breeder reactors (GCFRs). As presently conceived, GCFRs use pressure-equalized and vented fuel in which fission gases released from the solid matrix oxide fuel are transported through the fuel rod interstices and internal fission product traps to the fuel assembly vents, where they are swept away to external traps and storage. Since the predominant transport process under steady-state operating conditions is interdiffusion of gaseous fission products in helium, the diffusion properties of krypton-helium and xenon-helium couples have been measured over the range of GCFR temperature and pressure conditions ( -1 ) and expected temperature dependence to the 1.66 power (Tsup(1.66)) at lower pressures and temperatures. Additional work is in progress to measure the behaviour of the krypton-helium and xenon-helium couples in GCFR fuel rod charcoal delay traps. (author)

GASP: A computer code for calculating the thermodynamic and transport properties for ten fluids: Parahydrogen, helium, neon, methane, nitrogen, carbon monoxide, oxygen, fluorine, argon, and carbon dioxide. [enthalpy, entropy, thermal conductivity, and specific heat

Science.gov (United States)

Hendricks, R. C.; Baron, A. K.; Peller, I. C.

1975-01-01

A FORTRAN IV subprogram called GASP is discussed which calculates the thermodynamic and transport properties for 10 pure fluids: parahydrogen, helium, neon, methane, nitrogen, carbon monoxide, oxygen, fluorine, argon, and carbon dioxide. The pressure range is generally from 0.1 to 400 atmospheres (to 100 atm for helium and to 1000 atm for hydrogen). The temperature ranges are from the triple point to 300 K for neon; to 500 K for carbon monoxide, oxygen, and fluorine; to 600 K for methane and nitrogen; to 1000 K for argon and carbon dioxide; to 2000 K for hydrogen; and from 6 to 500 K for helium. GASP accepts any two of pressure, temperature and density as input conditions along with pressure, and either entropy or enthalpy. The properties available in any combination as output include temperature, density, pressure, entropy, enthalpy, specific heats, sonic velocity, viscosity, thermal conductivity, and surface tension. The subprogram design is modular so that the user can choose only those subroutines necessary to the calculations.

Thermal analysis of a coaxial helium panel of a cryogenic vacuum pump for advanced divertor of DIII-D tokamak

International Nuclear Information System (INIS)

Baxi, C.B.; Langhorn, A.; Schaubel, K.; Smith, J.

1991-08-01

It is planned to install a 50,000 1/s cryogenic pump for particle removal in the D3-D tokamak. A critical component of this cryogenic pump will be a helium panel which has to be maintained at a liquid helium temperature. The outer surface area of the helium panel has an area of 1 m 2 and consists of a 2.5 cm diameter, 10 m long tube. From design considerations, a coaxial geometry is preferable since it requires a minimum number of welds. However, the coaxial geometry also results in a counter flow heat exchanger arrangement, where the outgoing warm fluid will exchange heat with incoming cold fluid. This is of concern since the helium panel must be cooled from liquid nitrogen temperature to liquid helium temperature in less than 5 minutes for successful operation of the cryogenic pump. In order to analyze the thermal performance of the coaxial helium panel, a finite difference computer model of the geometry was prepared. The governing equations took into account axial as well as radial conduction through the tube walls. The variation of thermal properties was modeled. The results of the analysis showed that although the coaxial geometry behaves like a counter flow heat exchanger, within the operating range of the cryogenic pump a rapid cooldown of the helium panel from liquid nitrogen temperature to the operating temperature is feasible. A prototypical experiment was also performed at General Atomics (GA) which verified the concept and the analysis. 4 refs., 8 figs

Atmospheric helium and geomagnetic field reversals.

Science.gov (United States)

Sheldon, W. R.; Kern, J. W.

1972-01-01

The problem of the earth's helium budget is examined in the light of recent work on the interaction of the solar wind with nonmagnetic planets. It is proposed that the dominant mode of helium (He4) loss is ion pumping by the solar wind during geomagnetic field reversals, when the earth's magnetic field is very small. The interaction of the solar wind with the earth's upper atmosphere during such a period is found to involve the formation of a bow shock. The penetration altitude of the shock-heated solar plasma is calculated to be about 700 km, and ionization rates above this level are estimated for a cascade ionization (electron avalanche) process to average 10 to the 9th power ions/sq cm/sec. The calculated ionization rates and the capacity of the solar wind to remove ionized helium (He4) from the upper atmosphere during geomagnetic dipole reversals are sufficient to yield a secular equilibrium over geologic time scales. The upward transport of helium from the lower atmosphere under these conditions is found to be adequate to sustain the proposed loss rate.

Laszlo Tisza and the two-fluid model of superfluidity

Science.gov (United States)

Balibar, Sébastien

2017-11-01

The "two-fluid model" of superfluidity was first introduced by Laszlo Tisza in 1938. On that year, Tisza published the principles of his model as a brief note in Nature and two articles in French in the Comptes rendus de l'Académie des sciences, followed in 1940 by two other articles in French in the Journal de physique et le Radium. In 1941, the two-fluid model was reformulated by Lev Landau on a more rigorous basis. Successive experiments confirmed the revolutionary idea introduced by Tisza: superfluid helium is indeed a surprising mixture of two fluids with independent velocity fields. His prediction of the existence of heat waves, a consequence of his model, was also confirmed. Then, it took several decades for the superfluidity of liquid helium to be fully understood.

Electrostatic charging and levitation of helium II drops

International Nuclear Information System (INIS)

Niemela, J.J.

1997-01-01

Liquid Helium II drops, of diameter 1 mm or less, are charged with positive helium ions and subsequently levitated by static electric fields. Stable levitation was achieved for drops of order 100-150 micrometers in diameter. The suspended drops could be translated to arbitrary positions within the levitator using additional superimposed DC electric fields, and also could be made to oscillate stably about their average positions by means of an applied time-varying electric field. A weak corona discharge was used to produce the necessary ions for levitation. A novel superfluid film flow device, developed for the controlled deployment of large charged drops, is described. Also discussed is an adjustable electric fountain that requires only a field emission tip operating at modest potentials, and works in both Helium I and Helium II

Liquid helium

CERN Document Server

Atkins, K R

1959-01-01

Originally published in 1959 as part of the Cambridge Monographs on Physics series, this book addresses liquid helium from the dual perspectives of statistical mechanics and hydrodynamics. Atkins looks at both Helium Three and Helium Four, as well as the properties of a combination of the two isotopes. This book will be of value to anyone with an interest in the history of science and the study of one of the universe's most fundamental elements.

Effect of helium on tensile properties of vanadium alloys

Energy Technology Data Exchange (ETDEWEB)

Chung, H.M.; Billone, M.C.; Smith, D.L. [Argonne National Lab., IL (United States)

1997-08-01

Tensile properties of V-4Cr-4Ti (Heat BL-47), 3Ti-1Si (BL-45), and V-5Ti (BL-46) alloys after irradiation in a conventional irradiation experiment and in the Dynamic Helium Charging Experiment (DHCE) were reported previously. This paper presents revised tensile properties of these alloys, with a focus on the effects of dynamically generated helium of ductility and work-hardening capability at <500{degrees}C. After conventional irradiation (negligible helium generation) at {approx}427{degrees}C, a 30-kg heat of V-4Cr-4Ti (BL-47) exhibited very low uniform elongation, manifesting a strong susceptibility to loss of work-hardening capability. In contrast, a 15-kg heat of V-3Ti-1Si (BL -45) exhibited relatively high uniform elongation ({approx}4%) during conventional irradiation at {approx}427{degrees}C, showing that the heat is resistant to loss of work-hardening capability.

Classical hydrodynamics of an ideal incompressible fluid and vortex motion in helium II

International Nuclear Information System (INIS)

Mamaladze, Y.G.; Kiknadze, L.V.

1982-01-01

Vortex motion in the vicinity of a protuberance at a bounding surface in rotating helium II and in plane slits is considered from the standpoint of the vortex-formation mechanism, the equilibrium spatial vortex distribution, and the possibility of supercritical quasidissipationless vortex flow

Ab Initio Values of the Thermophysical Properties of Helium as Standards

Science.gov (United States)

Hurly, John J.; Moldover, Michael R.

2000-01-01

Recent quantum mechanical calculations of the interaction energy of pairs of helium atoms are accurate and some include reliable estimates of their uncertainty. We combined these ab initio results with earlier published results to obtain a helium-helium interatomic potential that includes relativistic retardation effects over all ranges of interaction. From this potential, we calculated the thermophysical properties of helium, i.e., the second virial coefficients, the dilute-gas viscosities, and the dilute-gas thermal conductivities of 3He, 4He, and their equimolar mixture from 1 K to 104 K. We also calculated the diffusion and thermal diffusion coefficients of mixtures of 3He and 4He. For the pure fluids, the uncertainties of the calculated values are dominated by the uncertainties of the potential; for the mixtures, the uncertainties of the transport properties also include contributions from approximations in the transport theory. In all cases, the uncertainties are smaller than the corresponding experimental uncertainties; therefore, we recommend the ab initio results be used as standards for calibrating instruments relying on these thermophysical properties. We present the calculated thermophysical properties in easy-to-use tabular form. PMID:27551630

Neovascular glaucoma after helium ion irradiation for uveal melanoma

International Nuclear Information System (INIS)

Kim, M.K.; Char, D.H.; Castro, J.L.; Saunders, W.M.; Chen, G.T.; Stone, R.D.

1986-01-01

Neovascular glaucoma developed in 22 of 169 uveal melanoma patients treated with helium ion irradiation. Most patients had large melanomas; no eyes containing small melanomas developed anterior segment neovascularization. The mean onset of glaucoma was 14.1 months (range, 7-31 months). The incidence of anterior segment neovascularization increased with radiation dosage; there was an approximately three-fold increase at 80 GyE versus 60 GyE of helium ion radiation (23% vs. 8.5%) (P less than 0.05). Neovascular glaucoma occurred more commonly in larger tumors; the incidence was not affected by tumor location, presence of subretinal fluid, nor rate of tumor regression. Fifty-three percent of patients had some response with intraocular pressures of 21 mmHg or less to a combination of antiglaucoma treatments

Positron collisions with helium and alkaline earth-like atoms

International Nuclear Information System (INIS)

Campbell, C.P.

1998-09-01

This doctoral thesis is subdivided into: 1. Theory of positron collisions with helium and alkaline earth-like atoms, 2. Positron collisions with helium, magnesium, calcium, zinc, 3. Intercomparison of positron scattering by all those elements. The appendix of this work gives details of the numerical calculations and expands on the wavefunctions used

New helium spectrum variable and a new helium-rich star

International Nuclear Information System (INIS)

Walborn, N.R.

1974-01-01

HD 184927, known previously as a helium-rich star, has been found to have a variable helium spectrum; the equivalent widths of five He I lines are larger by an average of 46 percent on a 1974 spectrogram than on one obtained with the same equipment in 1970. HD 186205 has been found to be a new, pronounced helium-rich star. (auth)

Project report: Experimental planning and verification of working fluids (WP 5)

DEFF Research Database (Denmark)

Babi, Deenesh Kavi

working fluid candidates a database is required that can be simultaneously searched in order to differentiate and determine whether the generated candidates are existing or novel. Also, the next step upon selection of the candidates is performing experiments in order to test and verify the generated...... working fluids. If performed properly, the experimental step is solely verification. Experiments can either be performed virtually (in order to further reduce the number of required experiments) and/or physically. Therefore the objective of this work was the development of a database of existing working......Computer-aided molecular design (CAMD) helps in the reduction of experiments for the selection/design of optimal working fluids. In reducing the number of experiments, solutions obtain by trial and error is replaced by solutions that are based on mixture-process properties. In generating optimal...

CISM Course on Nonlinear Waves in Real Fluids

CERN Document Server

1991-01-01

The study of materials which exhibit new and unconventional properties is of central importance for the devel- opment of advanced and refined technologies in many fields of engineering science. In this connection there has been a rapidly growing interest in real fluid effects on wave phenomena in the past few years. A prominent example is provided by Bethe-Zel'dovich-Thompson (BZT) fluids which have the distinguishing feature that they exhibit negative nonlinearity over a finite range of temperature and pressures in the pure vapour phase. However, two phase flows with and without phase change are an even richer source of new unexpected and previously thought impossible phenomena. Topics covered by this volume include waves in gases near the critical point, waves in retrograde fluids, temperature waves in superfluid helium and density waves in suspensions of particles in liquids. Clearly, the aim of the various contributions is twofold. First, they are intended to provide scientists and engineers working in th...

Non-equilibrium thermodynamics, heat transport and thermal waves in laminar and turbulent superfluid helium

Science.gov (United States)

Mongiovì, Maria Stella; Jou, David; Sciacca, Michele

2018-01-01

This review paper puts together some results concerning non equilibrium thermodynamics and heat transport properties of superfluid He II. A one-fluid extended model of superfluid helium, which considers heat flux as an additional independent variable, is presented, its microscopic bases are analyzed, and compared with the well known two-fluid model. In laminar situations, the fundamental fields are density, velocity, absolute temperature, and heat flux. Such a theory is able to describe the thermomechanical phenomena, the propagation of two sounds in liquid helium, and of fourth sound in superleak. It also leads in a natural way to a two-fluid model on purely macroscopical grounds and allows a small amount of entropy associated with the superfluid component. Other important features of liquid He II arise in rotating situations and in superfluid turbulence, both characterized by the presence of quantized vortices (thin vortex lines whose circulation is restricted by a quantum condition). Such vortices have a deep influence on the transport properties of superfluid helium, as they increase very much its thermal resistance. Thus, heat flux influences the vortices which, in turn, modify the heat flux. The dynamics of vortex lines is the central topic in turbulent superfluid helium. The model is generalized to take into account the vortices in different cases of physical interest: rotating superfluids, counterflow superfluid turbulence, combined counterflow and rotation, and mass flow in addition to heat flow. To do this, the averaged vortex line density per unit volume L, is introduced and its dynamical equations are considered. Linear and non-linear evolution equations for L are written for homogeneous and inhomogeneous, isotropic and anisotropic situations. Several physical experiments are analyzed and the influence of vortices on the effective thermal conductivity of turbulent superfluid helium is found. Transitions from laminar to turbulent flows, from diffusive to

Helium the disappearing element

CERN Document Server

Sears, Wheeler M

2015-01-01

The subject of the book is helium, the element, and its use in myriad applications including MRI machines, particle accelerators, space telescopes, and of course balloons and blimps. It was at the birth of our Universe, or the Big Bang, where the majority of cosmic helium was created; and stellar helium production continues. Although helium is the second most abundant element in the Universe, it is actually quite rare here on Earth and only exists because of radioactive elements deep within the Earth. This book includes a detailed history of the discovery of helium, of the commercial industry built around it, how the helium we actually encounter is produced within the Earth, and the state of the helium industry today. The gas that most people associate with birthday party balloons is running out. “Who cares?” you might ask. Well, without helium, MRI machines could not function, rockets could not go into space, particle accelerators such as those used by CERN could not operate, fiber optic cables would not...

Antiprotonic helium atomcules

Directory of Open Access Journals (Sweden)

Sauge Sébastien

2012-10-01

Full Text Available About 3% of antiprotons ( stopped in helium are long-lived with microsecond lifetimes, against picoseconds in all other materials. This unusual longevity has been ascribed to the trapping of on metastable bound states in He+ helium atom-molecules thus named atomcules. Apart from their unique dual structure investigated by laser spectroscopy – a near-circular quasi-classical Rydberg atom with l ~ n – 1 ~ 37 or a special diatomic molecule with a negatively charged nucleus in high rotational state with J = l – the chemical physics aspects of their interaction with other atoms or molecules constitute an interesting topic for molecular physics. While atomcules may resist to million collisions in helium, molecular contaminants such as H2 are likely to destroy them in a single one, down to very low temperatures. In the Born-Oppenheimer framework, we interpret the molecular interaction obtained by ab initio quantum chemical calculations in terms of classical reactive channels, with activation barriers accounting for the experiments carried out in He and H2. From classical trajectory Monte Carlo simulations, we show that the thermalization stage strongly quenches initial populations, thus reduced to a recovered 3 % trapping fraction. This work illustrates the pertinence of chemical physics concepts to the study of exotic processes involving antimatter. New insights into the physico-chemistry of cold interstellar radicals are anticipated.

New technique for enhancing helium production in ferritic materials

International Nuclear Information System (INIS)

Greenwood, L.R.; Graczyk, D.G.; Kneff, D.W.

1987-10-01

Analyses of iron samples irradiated up to 10 27 n/m 2 in HFIR found more helium than was expected from fast neutron reactions at high neutron fluences. The helium excess increases systematically with neutron exposure, suggesting a transmutation-driven process. The extra helium may be produced in two different ways, either by fast neutron reactions on the transmuted isotopes of iron or by a thermal neutron reaction with the radioactive isotope 55 Fe. Radiometric and mass spectrometric measurements of the iron isotopes composing the irradiated samples have been used to determine limits on the cross sections for each process. Either of these processes can be used to enhance helium production in ferritic materials during irradiations in mixed-spectrum reactors by isotopically enriching the samples. Further work is needed to clarify the reaction mechanisms and helium production cross sections. Our measurements determined the thermal neutron total absorption cross section of 55 Fe to be 13.2 +- 2.1 barns. 16 refs., 3 figs., 3 tabs

A liquid helium saver

International Nuclear Information System (INIS)

Avenel, O.; Der Nigohossian, G.; Roubeau, P.

1976-01-01

A cryostat equipped with a 'liquid helium saver' is described. A mass flow rate M of helium gas at high pressure is injected in a counter-flow heat exchanger extending from room to liquid helium temperature. After isenthalpic expansion through a calibrated flow impedance this helium gas returns via the low pressure side of the heat exchanger. The helium boil-off of the cryostat represents a mass flow rate m, which provides additional precooling of the incoming helium gas. Two operating regimes appear possible giving nearly the same efficiency: (1) high pressure (20 to 25 atm) and minimum flow (M . L/W approximately = 1.5) which would be used in an open circuit with helium taken from a high pressure cylinder; and (2) low pressure (approximately = 3 atm), high flow (M . L/W > 10) which would be used in a closed circuit with a rubber diaphragm pumping-compressing unit; both provide a minimum theoretical boil-off factor of about 8%. Experimental results are reported. (U.K.)

Superconducting cable cooling system by helium gas at two pressures

International Nuclear Information System (INIS)

Dean, J.W.

1977-01-01

Thermally contacting, oppositely streaming, cryogenic fluid streams in the same enclosure in a closed cycle changes the fluid from a cool high pressure helium gas to a cooler reduced pressure helium gas in an expander so as to be at different temperature ranges and pressures respectively in go and return legs that are in thermal contact with each other and in thermal contact with a longitudinally extending superconducting transmission line enclosed in the same cable enclosure that insulates the line from the ambient at a temperature T 1 . By first circulating the fluid from a refrigerator at one end of the line as a cool gas at a temperature range T 2 to T 3 in the go leg, then circulating the gas through an expander at the other end of the line where the gas becomes a cooler gas at a reduced pressure and at a reduced temperature T 4 and finally by circulating the cooler gas back again to the refrigerator in a return leg at a temperature range T 4 to T 5 , while in thermal contact with the gas in the go leg, and in the same enclosure therewith for compression into a higher pressure gas at T 2 in a closed cycle, where T 2 greater than T 3 and T 5 greater than T 4 , the fluid leaves the enclosure in the go leg as a gas at its coldest point in the go leg, and the temperature distribution is such that the line temperature decreases along its length from the refrigerator due to the cooling from the gas in the return leg

Analysis of a 115MW, 3 shaft, helium Brayton cycle

International Nuclear Information System (INIS)

Pradeepkumar, K.N.

2002-01-01

This research theme is originated from a development project that is going on in South Africa, for the design and construction of a closed cycle gas turbine plant using gas-cooled reactor as the heat source to generate 115 MW of electricity. South African Power utility company, Eskorn, promotes this developmental work through its subsidiary called PBMR (Pebble Bed Modular Reactor). Some of the attractive features of this plant are the inherent and passive safety features, modular geometry, small evacuation area, small infrastructure requirements for the installation and running of the plant, small construction time, quick starting and stopping and also low operational cost. This exercise is looking at the operational aspects of a closed cycle gas turbine, the finding of which will have a direct input towards the successful development and commissioning of the plant. A thorough understanding of the fluid dynamics in this three-shaft system and its transient performance analysis were the two main objectives of this research work. A computer programme called GTSI, developed by a previous Cranfield University research student, has been used in this as a base programme for the performance analysis. Some modifications were done on this programme to improve its control abilities. The areas covered in the performance analysis are Start-up, Shutdown and Load ramping. A detailed literature survey has been conducted to learn from the helium Turbo machinery experiences, though it is very limited. A critical analysis on the design philosophy of the PBMR is also carried out as part of this research work. The performance analysis has shown the advantage, disadvantage and impact of various power modulation methods suggested for the PBMR. It has tracked the effect of the operations of the various valves included in the PBMR design. The start-up using a hot gas injection has been analysed in detail and a successful start region has been mapped. A start-up procedure is also written

Design and analysis of helium Brayton power cycles for HiPER reactor

Energy Technology Data Exchange (ETDEWEB)

Sánchez, Consuelo, E-mail: csanchez@ind.uned.es [Dpto. Ingeniería Energética UNED, Madrid (Spain); Juárez, Rafael; Sanz, Javier [Dpto. Ingeniería Energética UNED, Madrid (Spain); Instituto de Fusión Nuclear/UPM, Madrid (Spain); Perlado, Manuel [Instituto de Fusión Nuclear/UPM, Madrid (Spain)

2013-10-15

Highlights: ► A helium Brayton cycle has been designed integrating the two energy sources of HiPER. ► The Brayton cycle has intercooling stages and a recovery process. ► The low temperature of HiPER heat sources results in low cycle efficiency (35.2%). ► Two inter-cooling stages and a reheating process increases efficiency to over 37%. ► Helium Brayton cycles are to be considered as candidates for HiPER power cycles. -- Abstract: Helium Brayton cycles have been studied as power cycles for both fission and fusion reactors obtaining high thermal efficiency. This paper studies several technological schemes of helium Brayton cycles applied for the HiPER reactor proposal. Since HiPER integrates technologies available at short term, its working conditions results in a very low maximum temperature of the energy sources, something that limits the thermal performance of the cycle. The aim of this work is to analyze the potential of the helium Brayton cycles as power cycles for HiPER. Several helium Brayton cycle configurations have been investigated with the purpose of raising the cycle thermal efficiency under the working conditions of HiPER. The effects of inter-cooling and reheating have specifically been studied. Sensitivity analyses of the key cycle parameters and component performances on the maximum thermal efficiency have also been carried out. The addition of several inter-cooling stages in a helium Brayton cycle has allowed obtaining a maximum thermal efficiency of over 36%, and the inclusion of a reheating process may also yield an added increase of nearly 1 percentage point to reach 37%. These results confirm that helium Brayton cycles are to be considered among the power cycle candidates for HiPER.

Design and analysis of helium Brayton power cycles for HiPER reactor

International Nuclear Information System (INIS)

Sánchez, Consuelo; Juárez, Rafael; Sanz, Javier; Perlado, Manuel

2013-01-01

Highlights: ► A helium Brayton cycle has been designed integrating the two energy sources of HiPER. ► The Brayton cycle has intercooling stages and a recovery process. ► The low temperature of HiPER heat sources results in low cycle efficiency (35.2%). ► Two inter-cooling stages and a reheating process increases efficiency to over 37%. ► Helium Brayton cycles are to be considered as candidates for HiPER power cycles. -- Abstract: Helium Brayton cycles have been studied as power cycles for both fission and fusion reactors obtaining high thermal efficiency. This paper studies several technological schemes of helium Brayton cycles applied for the HiPER reactor proposal. Since HiPER integrates technologies available at short term, its working conditions results in a very low maximum temperature of the energy sources, something that limits the thermal performance of the cycle. The aim of this work is to analyze the potential of the helium Brayton cycles as power cycles for HiPER. Several helium Brayton cycle configurations have been investigated with the purpose of raising the cycle thermal efficiency under the working conditions of HiPER. The effects of inter-cooling and reheating have specifically been studied. Sensitivity analyses of the key cycle parameters and component performances on the maximum thermal efficiency have also been carried out. The addition of several inter-cooling stages in a helium Brayton cycle has allowed obtaining a maximum thermal efficiency of over 36%, and the inclusion of a reheating process may also yield an added increase of nearly 1 percentage point to reach 37%. These results confirm that helium Brayton cycles are to be considered among the power cycle candidates for HiPER

Helium mobility in advanced nuclear ceramics

International Nuclear Information System (INIS)

Agarwal, Shradha

2014-01-01

The main goal of this work is to improve our knowledge on the mechanisms able to drive the helium behaviour in transition metal carbides and nitrides submitted to thermal annealing or ion irradiation. TiC, TiN and ZrC polycrystals were implanted with 3 MeV 3 He ions at room temperature in the fluence range 2 * 10 15 et 6 * 10 16 cm -2 . Some of them have been pre-irradiated with self-ions (14 MeV Ti or Zr). Fully controlled thermal annealing tests were subsequently carried out in the temperature range 1000 - 1600 C for two hours. The evolution of the helium depth distribution in function of implantation dose, temperature and pre-irradiation dose was measured thanks to the deuteron-induced nuclear reaction 3 He(d, p 0 ) 4 He between 900 keV and 1.8 MeV. The microstructure of implanted and annealed samples was investigated by transmission electron microscopy on thin foils prepared using the FIB technique. Additional characterization tools, as X-ray diffraction and Raman microspectrometry, have been also applied in order to obtain complementary information. Among the most relevant results obtained, the following have to be outlined: - double-peak helium depth profile was measured on as implanted sample for the three compounds. The first peak is located near the end of range and includes the major part of helium, a second peak located close to the surface corresponds to the helium atoms trapped by the native vacancies; - the helium retention capacity in transition metal carbides and nitrides submitted to fully controlled thermal treatments varies according to ZrC 0.92 ≤ TiC 0.96 ≤ TiN 0.96 ; - whatever the investigated material, a self-ion-induced pre-damaging does not modify the initial helium profile extent. The influence of the post-implantation thermal treatment remains preponderant in any case; - the apparent diffusion coefficient of helium is in the range 4 * 10 -18 - 2 * 10 -17 m 2 s -1 in TiC0.96 and 3.5 * 10 -19 - 5.3 * 10 -18 m 2 s -1 in TiN 0.96 between

Physics of quantum fluids new trends and hot topics in atomic and polariton condensates

CERN Document Server

Modugno, Michele

2013-01-01

The study of quantum fluids, stimulated by the discovery of superfluidity in liquid helium, has experienced renewed interest after the observation of Bose-Einstein condensation (BEC) in ultra-cold atomic gases and the observation a new type of quantum fluid with specific characteristics derived from its intrinsic out-of-equilibrium nature. The main objective of this book is to take a snapshot of the state-of-the-art of this fast moving field with a special emphasis on the hot topics and new trends. Bringing together the most active specialists of the two areas (atomic and polaritonic quantum fluids), we expect that this book will facilitate the exchange and the collaboration between these two communities working on subjects with very strong analogies.

CO{sub 2} expansion work recovery by impulse turbine

Energy Technology Data Exchange (ETDEWEB)

Toendell, Espen

2006-07-01

This study focuses on refrigeration processes with relatively low cooling capacities and hereby low circulation rates. The presented theory for turbines focuses on work extraction in impulse turbines. For an impulse turbine, the optimal rotational speed gives a turbine blade tip speed equal to half the nozzle jet velocity. With small volume flow rates, the turbine will have small dimensions, and hereby the rotational speed will be high. Together with principles for work extraction, the losses in the turbine were discussed. The main losses are nozzle losses (Friction and incomplete flashing), rotational losses, disc friction, windage, changing angles, non-rotational losses, fluid friction between jet and turbine blade, jet not hitting turbine blade, mechanical losses in bearings. A literature survey was made to show some examples on two-phase turbines and to create a theoretical basis for fluid expansion in a nozzle. The literature survey on two-phase expanders showed some examples on Helium expanders with small dimensions and good efficiencies. Compared to a helium expander, a CO{sub 2} expander will be working on a higher pressure, and hereby some extra losses must be expected. Some work on expander for R134a was also referred. That work was however focused on high cooling capacities, which means that the R134a expander will have much higher mass flow than the CO{sub 2} expander in this study. The literature survey on fluid expansion and nucleation showed that the critical radius is important in nucleation. The critical radius is dependent on the surface tension and the difference between the liquid saturation pressure and the local pressure. For the current study, understanding of nucleation will be important in order to understand the function of the nozzle. Finally some models for critical flow were presented (author) (ml)

Physics of quantum fluids. New trends and hot topics in atomic and polariton condensates

Energy Technology Data Exchange (ETDEWEB)

Bramati, Alberto [Paris Univ. (France). Laboratoire Kastler Brossel; Centre National de la Recherche Scientifique (CNRS), 75 - Paris (France); Modugno, Michele (eds.) [IKERBASQUE, Bilbao (Spain); Univ. del Pais Vasco, Bilbao (Spain). Dept. de Fisica Teorica e Historia de la Ciencia

2013-10-01

Provides an overview of the field of quantum fluids. Presents analogies and differences between polariton and atomic quantum fluids. With contributions from the major actors in the field. Explains a new type of quantum fluid with specific characteristics. The study of quantum fluids, stimulated by the discovery of superfluidity in liquid helium, has experienced renewed interest after the observation of Bose-Einstein condensation (BEC) in ultra-cold atomic gases and the observation a new type of quantum fluid with specific characteristics derived from its intrinsic out-of-equilibrium nature. The main objective of this book is to take a snapshot of the state-of-the-art of this fast moving field with a special emphasis on the hot topics and new trends. Bringing together the most active specialists of the two areas (atomic and polaritonic quantum fluids), we expect that this book will facilitate the exchange and the collaboration between these two communities working on subjects with very strong analogies.

New knowledge on the temperature-entropy saturation boundary slope of working fluids

International Nuclear Information System (INIS)

Su, Wen; Zhao, Li; Deng, Shuai

2017-01-01

The slope of temperature-entropy saturation boundary of working fluids has a significant effect on the thermodynamic performance of cycle processes. However, for the working fluids used in cycles, few studies have been conducted to analyze the saturated slope from the molecular structure and mixture composition. Thus, in this contribution, an analytical expression on the slope of saturated curve is obtained based on the highly accurate Helmholtz energy equation. 14 pure working fluids and three typical binary mixtures are employed to analyze the influence of molecular groups and mixture compositions on the saturated slope, according to the correlated parameters of Helmholtz energy equation. Based on the calculated results, a preliminary trend is demonstrated that with an increase of the number of molecular groups, the positive liquid slope of pure fluids increases and the vapor slope appears positive sign in a narrow temperature range. Particularly, for the binary mixtures, the liquid slope is generally located between the corresponding pure fluids', while the vapor slope can be infinity by mixing dry and wet fluids ingeniously. It can be proved through the analysis of mixtures' saturated slope that three types of vapor slope could be obtained by regulating the mixture composition. - Highlights: • The saturated slope is derived from the Helmholtz function for working fluids. • The effect of molecular structure on the saturated slope is analyzed. • The variation of saturated slope with the mixture composition is investigated.

Canada's helium output rising fast

Energy Technology Data Exchange (ETDEWEB)

1966-12-01

About 12 months from now, International Helium Limited will be almost ready to start up Canada's second helium extraction plant at Mankota, in Saskatchewan's Wood Mountain area about 100 miles southwest of Moose Jaw. Another 80 miles north is Saskatchewan's (and Canada's) first helium plant, operated by Canadian Helium and sitting on a gas deposit at Wilhelm, 9 miles north of Swift Current. It contains almost 2% helium, some COD2U, and the rest nitrogen. One year in production was apparently enough to convince Canadian Helium that the export market (it sells most of its helium in W. Europe) can take a lot more than it's getting. Construction began this summer on an addition to the Swift Current plant that will raise its capacity from 12 to 36MMcf per yr when it goes on stream next spring. Six months later, International Helium's 40 MMcf per yr plant to be located about 4 miles from its 2 Wood Mountain wells will double Canada's helium output again.

Diffusion of helium and nucleation-growth of helium-bubbles in metallic materials

International Nuclear Information System (INIS)

Zhang Chonghong; Chen Keqin; Wang Yinshu

2001-01-01

Studies of diffusion and aggregation behaviour of helium in metallic materials are very important to solve the problem of helium embrittlement in structural materials used in the environment of nuclear power. Experimental studies on helium diffusion and aggregation in austenitic stainless steels in a wide temperature range have been performed in authors' research group and the main results obtained are briefly summarized. The mechanism of nucleation-growth of helium-bubbles has been discussed and some problems to be solved are also given

Asteroseismic estimate of helium abundance of a solar analog binary system

Energy Technology Data Exchange (ETDEWEB)

Verma, Kuldeep; Antia, H. M. [Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India); Faria, João P.; Monteiro, Mário J. P. F. G. [Centro de Astrofísica da Universidade do Porto, Rua das Estrelas, 4150-762 Porto (Portugal); Basu, Sarbani [Astronomy Department, Yale University, P. O. Box 208101, New Haven, CT 065208101 (United States); Mazumdar, Anwesh [Homi Bhabha Centre for Science Education, TIFR, V. N. Purav Marg, Mankhurd, Mumbai 400088 (India); Appourchaux, Thierry [Institut d' Astrophysique Spatiale, Université Paris XI-CNRS (UMR8617), Batiment 121, F-91405 Orsay Cedex (France); Chaplin, William J. [School of Physics and Astronomy, University of Birmingham, B15 2TT (United Kingdom); García, Rafael A. [Laboratoire AIM, CEA/DSM, CNRS, Université Paris Diderot, IRFU/SAp, Centre de Saclay, F-91191 Gif-sur-Yvette Cedex (France); Metcalfe, Travis S. [Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark)

2014-08-01

16 Cyg A and B are among the brightest stars observed by Kepler. What makes these stars more interesting is that they are solar analogs. 16 Cyg A and B exhibit solar-like oscillations. In this work we use oscillation frequencies obtained using 2.5 yr of Kepler data to determine the current helium abundance of these stars. For this we use the fact that the helium ionization zone leaves a signature on the oscillation frequencies and that this signature can be calibrated to determine the helium abundance of that layer. By calibrating the signature of the helium ionization zone against models of known helium abundance, the helium abundance in the envelope of 16 Cyg A is found to lie in the range of 0.231 to 0.251 and that of 16 Cyg B lies in the range of 0.218 to 0.266.

Fluid Induced Vibration Analysis of a Cooling Water Pipeline for the HANARO CNS

International Nuclear Information System (INIS)

Kim, Bong Soo; Lee, Young Sub; Kim, Ik Soo; Kim, Young Ki

2007-01-01

CNS is the initial of Cold Neutron Source and the CNS facility system consists of hydrogen, a vacuum, a gas blanketing, a helium refrigeration and a cooling water supply system. Out of these subsystems, the helium refrigeration system has the function of removal of heat from a thermal neutron under reactor operation. Therefore, HRS (helium refrigeration system) must be under normal operation for the production of cold neutron. HRS is mainly made up of a helium compressor and a coldbox. This equipment is in need of cooling water to get rid of heat generation under stable operation and a cooling water system is essential to maintain the normal operation of a helium compressor and a coldbox. The main problem for the cooling water system is the vibration issue in the middle of operation due to a water flow in a pipeline. In order to suppress the vibration problem for a pipeline, the characteristics of a pipeline and fluid flow must be analyzed in detail. In this paper, fluid induced vibration of a cooling water pipe is analyzed numerically and the stability of the cooling water pipeline is investigated by using pipe dynamic theory

Verification test for helium panel of cryopump for DIII-D advanced divertor

International Nuclear Information System (INIS)

Baxi, C.B.; Laughon, G.J.; Langhorn, A.R.; Schaubel, K.M.; Smith, J.P.; Gootgeld, A.M.; Campbell, G.L.; Menon, M.M.

1992-01-01

It is planned to install a cryogenic pump in the lower divertor portion of the DIII-D tokamak with a pumping speed of 50000 ell/s and an exhaust of 2670 Pa-ell/s (20 Torr-ell/s). A coaxial counter flow configuration has been chosen for the helium panel of this cryogenic pump. This paper evaluates cool-down rates and fluid stability of this configuration. A prototypic test was performed at General Atomics (GA) to increase confidence in the design. It was concluded that the helium panel cooldown rate agreed quite well with analytical prediction and was within acceptable limits. The design flow rate proved stable and two-phase pressure drop can be predicted quite accurately

Potential of organic Rankine cycle using zeotropic mixtures as working fluids for waste heat recovery

International Nuclear Information System (INIS)

Li, You-Rong; Du, Mei-Tang; Wu, Chun-Mei; Wu, Shuang-Ying; Liu, Chao

2014-01-01

The performance of the ORC (organic Rankine cycle) systems using zeotropic mixtures as working fluids for recovering waste heat of flue gas from industrial boiler is examined on the basis of thermodynamics and thermo-economics under different operating conditions. In order to explore the potential of the mixtures as the working fluids in the ORC, the effects of various mixtures with different components and composition proportions on the system performance have been analyzed. The results show that the compositions of the mixtures have an important effect on the ORC system performance, which is associated with the temperature glide during the phase change of mixtures. From the point of thermodynamics, the performance of the ORC system is not always improved by employing the mixtures as the working fluids. The merit of the mixtures is related to the restrictive conditions of the ORC, different operating conditions results in different conclusions. At a fixed pinch point temperature difference, the small mean heat transfer temperature difference in heat exchangers will lead to a larger heat transfer area and the larger total cost of the ORC system. Compared with the ORC with pure working fluids, the ORC with the mixtures presents a poor economical performance. - Highlights: • Organic Rankine cycle system with the mixture working fluids for recovering waste heat is analyzed. • The performance of the mixture-fluid ORC is related to temperature glide in phase change of mixture working fluids. • The relative merit of the mixture working fluids depends on the restrictive operation conditions of the ORC. • The ORC with mixture working fluid presents a poor economical performance compared with the pure working fluid case

Creep properties of Hastelloy X in a carburizing helium environment

International Nuclear Information System (INIS)

Nakanishi, T.; Kawakami, H.

1982-01-01

In this work, we investigate the environmental effect on the creep behavior of Hastelloy X at 900 0 C in helium and air. Since helium coolant in HTGR is expected to be carburizing and very weakly oxidizing for most metals, testings were focused on the effect of carburizing and slight oxidation. Carburization decreases secondary creep strain rate and delays tertiary creep initiation. On the other hand, the crack growth rate on the specimen surface is enhanced due to very weak oxidation in helium, therefore the tertiary creep strain rate becomes larger than that in air. The rupture time of Hastelloy X was shorter in helium when compared with in air. Stress versus rupture time curves for both environments do not deviate with each other during up to 5000 hours test, and a ratio of rupture stress in helium to that in air was about 0.9

Mechanical property changes induced in structural alloys by neutron irradiations with different helium to displacement ratios*1

Science.gov (United States)

Mansur, L. K.; Grossbeck, M. L.

1988-07-01

Effects of helium on mechanical properties of irradiated structural materials are reviewed. In particular, variations in response to the ratio of helium to displacement damage serve as the focus. Ductility in creep and tensile tests is emphasized. A variety of early work has led to the current concentration on helium effects for fusion reactor materials applications. A battery of techniques has been developed by which the helium to displacement ratio can be varied. Our main discussion is devoted to the techniques of spectral tailoring and isotopic alloying currently of interest for mixed-spectrum reactors. Theoretical models of physical mechanisms by which helium interacts with displacement damage have been developed in terms of hardening to dislocation motion and grain boundary cavitation. Austenitic stainless steels, ferritic/martensitic steels and vanadium alloys are considered. In each case, work at low strain rates, where the main problems may lie, at the helium to displacement ratios appropriate to fusion reactor materials is lacking. Recent experimental evidence suggests that both in-reactor and high helium results may differ substantially from post-irradiation or low helium results. It is suggested that work in these areas is especially needed.

High-density equation of state for helium and its application to bubbles in solids

International Nuclear Information System (INIS)

Wolfer, W.G.

1980-06-01

Helium, produced by transmutations or injected, causes bubble formation in solids at elevated temperatures. For small bubbles, the gas pressure required to balance the surface tension reaches values which far exceed those obtainable in experiments to measure the equation of state for helium gas. Therefore, empirical gas laws cannot be considered applicable to the fluid-like densities existing in small bubbles. In order to remedy this situation, an equation of state for helium was developed from the theory of the liquid state. At very low densities, this theoretically derived equation of state agrees with experimental results. For high densities, however, gas pressures are predicted which are significantly higher than those derived from the ideal gas law, but also significantly lower than pressures obtained with the van der Waals law. When applied to equilibrium bubbles in solids, it is found that the high-density equation of state leads to less bubble swelling than the van der Waals law, but more than the ideal gas law. Furthermore, the number of helium atoms in equilibrium bubbles is nearly independent of temperature

Application of helium isotopes in shallow groundwaters for geothermal energy exploration in the Upper Rhine Graben

International Nuclear Information System (INIS)

Freundt, Florian

2017-01-01

The helium isotope system is an established tool in hydrology for identifying mantle fluids in deep aquifers. This study applies the helium tracer system for the first time in shallow, unconfined aquifers of the Upper Rhine Graben. The Graben is a part of the Cenozoic Rift system of Western and Central Europe, a continental rift zone with unusually high geothermal gradients, making it an ideal region of Germany for geothermal energy development. The aim of this study is to develop a suite of natural groundwater tracers able to achieve a cost and effort reduction in geothermal prospection. The 3 He/ 4 He-ratio is therefore applied, as part of a multi-tracer approach including 3 H, δ 18 O, δ 2 H, δ 13 C, 14 C and 222 Rn, to identify and locate fault zones with suitable permeabilities for power plant operation. Three target areas along the graben were studied, each located on one of the main fault lines. A mantle-derived helium signature could be identified and separated from tritiogenic helium in a shallow aquifer in the north-west of the Graben. The mixing component of mantle-derived fluid in the shallow groundwater is calculated to reach up to 5%, based on the analysis of the 3 He/ 4 He isotope system. The employed method proves that the local permeability of the fault zone is high. The origin of the locally occurring upwelling of salinated water can be redetermined by the data.

Transition to ballistic regime for heat transport in helium II

Energy Technology Data Exchange (ETDEWEB)

Sciacca, Michele, E-mail: michele.sciacca@unipa.it [Dipartimento Scienze Agrarie e Forestali, Università degli studi di Palermo, Viale delle Scienze, 90128 Palermo (Italy); Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Catalonia (Spain); Sellitto, Antonio, E-mail: ant.sellitto@gmail.com [Dipartimento di Matematica, Informatica ed Economia, Università della Basilicata, Campus Macchia Romana, 85100 Potenza (Italy); Jou, David, E-mail: david.jou@uab.cat [Departament de Física, Universitat Autònoma de Barcelona, 08193 Bellaterra, Catalonia (Spain); Institut d' Estudis Catalans, Carme 47, 08001 Barcelona, Catalonia (Spain)

2014-07-04

The size-dependent and flux-dependent effective thermal conductivity of narrow capillaries filled with superfluid helium is analyzed from a thermodynamic continuum perspective. The classical Landau evaluation of the effective thermal conductivity of quiescent superfluid, or the Gorter–Mellinck regime of turbulent superfluids, is extended to describe the transition to ballistic regime in narrow channels wherein the radius R is comparable to (or smaller than) the phonon mean-free path ℓ in superfluid helium. To do so, we start from an extended equation for the heat flux incorporating non-local terms, and take into consideration a heat slip flow along the walls of the tube. This leads from an effective thermal conductivity proportional to R{sup 2} (Landau regime) to another one proportional to Rℓ (ballistic regime). We consider two kinds of flows: along cylindrical pipes and along two infinite parallel plates. - Highlights: • Heat transport in counterflow helium in the ballistic regime. • The one-fluid model based on the Extended Thermodynamics is used. • The transition from the Landau regime to the ballistic regime. • The transition from quantum turbulence to ballistic regime.

Limitations of superfluid helium droplets as host system revealed by electronic spectroscopy of embedded molecules

Energy Technology Data Exchange (ETDEWEB)

Premke, Tobias

2016-02-19

Superfluid helium nanodroplets serve a unique cryogenic host system ideal to prepare cold molecules and clusters. Structures as well as dynamic processes can be examined by means of high resolution spectroscopy. Dopant spectra are accompanied by helium-induced spectroscopic features which reveal information on the dopant to helium interaction. For this reason the experimental research focuses on the investigation of such helium-induced effects in order to provide new information on the microsolvation inside the droplets. Since the quantitative understanding of helium-induced spectral features is essential to interpret molecular spectra recorded in helium droplets, this study contributes further experimental details on microsolvation in superfluid helium droplets. For this purpose two contrary systems were examined by means of high resolution electronic spectroscopy. The first one, phthalocyanine (Pc), is a planar organic molecule offering a huge and planar surface to the helium atoms and thus, the non-superfluid helium solvation layer can form different structures. The second system is iodine and in contrast to Pc it is of simple molecular shape. That means that in this case different complex structures of the non-superfluid helium solvation layer and the dopant can be expected to be avoided. Thus, both molecules should show clear differences in their microsolvation behavior. In this work a detailed examination of different spectroscopic properties of phthalocyanine is given by means of fluorescence excitation and dispersed emission spectroscopy. It raises legitimate doubts about the assignment of experimentally observed signals to features predicted by the model of the microsolvation. Even though there are no experimental observations which disprove the empirical model for the solvation in helium droplets, an unambiguous assignment of the helium-induced spectroscopic structures is often not possible. In the second part of this work, the investigation of the

Performance analysis a of solar driven organic Rankine cycle using multi-component working fluids

DEFF Research Database (Denmark)

Baldasso, E.; Andreasen, J. G.; Modi, A.

2015-01-01

suitable control strategy and both the overall annual production and the average solar to electrical efficiency are estimated with an annual simulation. The results suggest that the introduction of binary working fluids enables to increase the solar system performance both in design and part-load operation....... cycle. The purpose of this paper is to optimize a low temperature organic Rankine cycle tailored for solar applications. The objective of the optimization is the maximization of the solar to electrical efficiency and the optimization parameters are the working fluid and the turbine inlet temperature...... and pressure. Both pure fluids and binary mixtures are considered as possible working fluids and thus one of the primary aims of the study is to evaluate whether the use of multi-component working fluids might lead to increased solar to electrical efficiencies. The considered configuration includes a solar...

The development of working memory capacity and fluid intelligence in children

OpenAIRE

Engel de Abreu, Pascale; Gathercole, S; Conway, A

2010-01-01

A longitudinal study was conducted to investigate the relationship between working memory capacity and fluid intelligence and how this relationship develops in early childhood. The major aim was to determine which aspect of the working memory system – short-term storage or executive attention – drives the relationship with fluid intelligence. A sample of 119 children was followed from kindergarten to second grade and completed multiple assessments of short-term memory, wor...

A description of stress driven bubble growth of helium implanted tungsten

International Nuclear Information System (INIS)

Sharafat, Shahram; Takahashi, Akiyuki; Nagasawa, Koji; Ghoniem, Nasr

2009-01-01

Low energy (<100 keV) helium implantation of tungsten has been shown to result in the formation of unusual surface morphologies over a large temperature range (700-2100 deg. C). Simulation of these macroscopic phenomena requires a multiscale approach to modeling helium transport in both space and time. We present here a multiscale helium transport model by coupling spatially-resolved kinetic rate theory (KRT) with kinetic Monte Carlo (KMC) simulation to model helium bubble nucleation and growth. The KRT-based HEROS Code establishes defect concentrations as well as stable helium bubble nuclei as a function of implantation parameters and position from the implanted surface and the KMC-based Mc-HEROS Code models the growth of helium bubbles due to migration and coalescence. Temperature- and stress-gradients can act as driving forces, resulting in biased bubble migration. The Mc-HEROS Code was modified to simulate the impact of stress gradients on bubble migration and coalescence. In this work, we report on bubble growth and gas release of helium implanted tungsten W/O stress gradients. First, surface pore densities and size distributions are compared with available experimental results for stress-free helium implantation conditions. Next, the impact of stress gradients on helium bubble evolution is simulated. The influence of stress fields on bubble and surface pore evolution are compared with stress-free simulations. It is shown that near surface stress gradients accelerate helium bubbles towards the free surface, but do not increasing average bubble diameters significantly.

Research and development of a helium-4 based solar neutrino detector

International Nuclear Information System (INIS)

Lanou, R.E.; Maris, H.J.; Seidel, G.M.

1990-12-01

We report on work accomplished in the first 30 months of a research and development program to investigate the feasibility of a new technique to detect solar neutrinos in superfluid helium. Accomplishments include the successful completion of design, construction and operation of the entire cryogenic, mechanical and electronic apparatus. During the last several months we have begun a series of experiments in superfluid helium to test the method. Experimental results include the first observation of the combined physical processes essential to the detection technique: ballistic roton generation by energetic charged particles, quantum evaporation of helium at a free surface and bolometric detection of the evaporated helium by physisorption on a cold silicon wafer. Additional results are also presented

Artificial dissipation models applied to Navier-Stokes equations for analysis of supersonic flow of helium gas around a geometric configuration ramp type

International Nuclear Information System (INIS)

Rocha, Jussie Soares da; Maciel, Edisson Savio de G.; Lira, Carlos A.B. de O.

2015-01-01

Very High Temperature Gas Cooled Reactors - VHTGRs are studied by several research groups for the development of advanced reactors that can meet the world's growing energy demand. The analysis of the flow of helium coolant around the various geometries at the core of these reactors through computational fluid dynamics techniques is an essential tool in the development of conceptual designs of nuclear power plants that provide added safety. This analysis suggests a close analogy with aeronautical cases widely studied using computational numerical techniques to solve systems of governing equations for the flow involved. The present work consists in solving the Navier-Stokes equations in a conservative form, in two-dimensional space employing a finite difference formulation for spatial discretization using the Euler method for explicit marching in time. The physical problem of supersonic laminar flow of helium gas along a ramp configuration is considered. For this, the Jameson and Mavriplis algorithm and the artificial dissipations models linear and nonlinear of Pulliam was implemented. A spatially variable time step is employed aiming to accelerate the convergence to the steady state solution. The main purpose of this work is to study the cited dissipation models and describe their characteristics in relation to the overall quality of the solution, aiming preliminary results for the development of computational tools of dynamic analysis of helium flow for the VHTGR core. (author)

Emission Spectra of Hydrogen-Seeded Helium Arcjets

National Research Council Canada - National Science Library

Welle, R

2000-01-01

.... This work reports on a recent set of experiments in which emission spectra of the plume of a helium arcjet were acquired and analyzed to obtain information on the internal energy modes of the arcjet...

A hydrodynamic model for superfluid helium with vortices

International Nuclear Information System (INIS)

Lhuillier, D.; Francois, M.

1975-01-01

Although their existence is experimentally well verified, the so-called mutual friction force Fsub(sn) and superfluid friction force Fsub(s) cannot emerge from the Landau irrotational model of superfluidity. Up to now these forces have merely been added to the Landau equations but this is untenable since, as a consequence, one destroys the irrotationality condition with which the equations have expressly been built. It is shown that these friction forces appear in a natural way in a model where superfluid helium with vortices is compared to a fluid with a conserved intrinsic momentum. (Auth.)

Self-trapping of helium in metals

International Nuclear Information System (INIS)

Wilson, W.D.; Bisson, C.L.; Baskes, M.I.

1981-01-01

Atomistic calculations are presented which demonstrate that helium atoms in a metal lattice are able to cluster with each other, producing vacancies and nearby self-interstitial defects. Even a small number of helium atoms is found to be sufficient to create these large distortions. As few as five interstitial helium can spontaneously produce a lattice vacancy and nearby self-interstitial. An eight-helium-atom cluster gives rise to two such defects, and 16 helium atoms to more than five self-interstitial vacancy pairs. It was noted that the self-interstitials prefer to agglomerate on the same ''side'' of the helium cluster rather than to spread themselves out uniformly. The binding energy of each additional helium atom to these clusters increases with helium concentration and the trap is apparently unsaturable. A rate theory using these atomistic binding energies has been used to calculate the kinetics of helium-bubble nucleation and growth. The results are consistent with measurements of the properties of helium resulting from tritium decay

Cryogenic system with GM cryocooler for krypton, xenon separation from hydrogen-helium purge gas

Energy Technology Data Exchange (ETDEWEB)

Chu, X. X.; Zhang, D. X.; Qian, Y.; Liu, W. [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, 201800 (China); Zhang, M. M.; Xu, D. [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190 (China)

2014-01-29

In the thorium molten salt reactor (TMSR), fission products such as krypton, xenon and tritium will be produced continuously in the process of nuclear fission reaction. A cryogenic system with a two stage GM cryocooler was designed to separate Kr, Xe, and H{sub 2} from helium purge gas. The temperatures of two stage heat exchanger condensation tanks were maintained at about 38 K and 4.5 K, respectively. The main fluid parameters of heat transfer were confirmed, and the structural heat exchanger equipment and cold box were designed. Designed concentrations after cryogenic separation of Kr, Xe and H{sub 2} in helium recycle gas are less than 1 ppb.

Verification test for helium panel of cryopump for DIII-D advanced divertor

International Nuclear Information System (INIS)

Baxi, C.B.; Laughon, G.J.; Langhorn, A.R.; Schaubel, K.M.; Smith, J.P.; Gootgeld, A.M.; Campbell, G.L.; Menon, M.M.

1991-10-01

It is planned to install a cryogenic pump in the lower divertor portion of the D3-D tokamak with a pumping speed of 50000 ell/s and an exhaust of 2670 Pa-ell/s (20 Torr-ell s). A coaxial counter flow configuration has been chosen for the helium panel of this cryogenic pump. This paper evaluates cooldown rates and fluid stability of this configuration. A prototypic test was performed at General Atomics (GA) to increase confidence in the design. It was concluded that the helium panel cooldown rate agreed quite well with analytical prediction and was within acceptable limits. The design flow rate proved stable and two-phase pressure drop can be predicted quite accurately. 8 refs., 5 figs., 1 tab

High Temperature Heat Pump Integration using Zeotropic Working Fluids for Spray Drying Facilities

DEFF Research Database (Denmark)

Zühlsdorf, Benjamin; Bühler, Fabian; Mancini, Roberta

2017-01-01

source and sink best possibly. Therefore, a set of six common working fluids is defined and the possible binary mixtures of these fluids are analyzed. The performance of the fluids is evaluated based on the energetic performance (COP) and the economic potential (NPV). The results show...... and show a large potential to reuse the excess heat from exhaust gases. This study analyses a heat pump application with an improved integration by choosing the working fluid as a mixture in such a way, that the temperature glide during evaporation and condensation matches the temperature glide of the heat...

Reverse convection in helium and other fluids in the high speed rotating frame: negative and positive buoyancy effects

International Nuclear Information System (INIS)

Igra, R.; Scurlock, R.G.; Wu, Y.Y.

1986-01-01

Experimental studies of thermo-syphon flows in radial tubes and loops between the axis and the periphery of a rotating helium cryostat have shown that when heat is supplied at an intermediate radius, the heat is carried radially inwards as A flow and radially outwards as B flow. The results with helium suggest that while the steady state patterns of the A and B flows are complex, the heat is divided approximately equally between the conventional A flow and the reverse B flow. A model of convective heating in the rotating frame is presented and two necessary conditions for reverse convection are identified and discussed. The model predicts reverse convection in liquid nitrogen and this is confirmed by experimental measurement. An array of radial ducts is proposed for the cooling of a superconducting AC generator in order to counter the effects of reverse convection in the helium refrigerant

Helium generation in fusion-reactor materials. Progress report, October-December 1982

International Nuclear Information System (INIS)

Kneff, D.W.; Farrar, H. IV.

1982-01-01

The objectives of this work are to measure helium generation rates of materials for Magnetic Fusion Reactor applications in the Be(d,n) neutron environment, to characterize this neutron environment, and to develop helium accumulation neutron dosimeters for routine neutron fluence and energy spectrum measurements in Be(d,n) and Li(d,n) neutron fields

Thermo-economic analysis and selection of working fluid for solar organic Rankine cycle

International Nuclear Information System (INIS)

Desai, Nishith B.; Bandyopadhyay, Santanu

2016-01-01

Highlights: • Concentrating solar power plant with organic Rankine cycle. • Thermo-economic analysis of solar organic Rankine cycle. • Performance evaluation for different working fluids. • Comparison diagram to select appropriate working fluid. - Graphical Abstract: Display Omitted - Abstract: Organic Rankine cycle (ORC), powered by line-focusing concentrating solar collectors (parabolic trough collector and linear Fresnel reflector), is a promising option for modular scale. ORC based power block, with dry working fluids, offers higher design and part-load efficiencies compared to steam Rankine cycle (SRC) in small-medium scale, with temperature sources up to 400 °C. However, the cost of ORC power block is higher compared to the SRC power block. Similarly, parabolic trough collector (PTC) system has higher optical efficiency and higher cost compared to linear Fresnel reflector (LFR) system. The thermodynamic efficiencies and power block costs also vary with working fluids of the Rankine cycle. In this paper, thermo-economic comparisons of organic Rankine and steam Rankine cycles powered by line-focusing concentrating solar collectors are reported. A simple selection methodology, based on thermo-economic analysis, and a comparison diagram for working fluids of power generating cycles are also proposed. Concentrating solar power plants with any collector technology and any power generating cycle can be compared using the proposed methodology.

RELAP/SCDAPSIM/MOD4.0 modification for transient accident scenario of Test Blanket Modules in ITER involving helium flows into heavy liquid metal

Energy Technology Data Exchange (ETDEWEB)

Freixa, J.; Pérez, M.; Mas de les Valls, E.; Batet, L.; Sandeep, T.; Chaudhari, V.; Reventós, F.

2015-07-01

The Institute for Plasma Research (IPR), India, is currently involved in the design and development of its Test Blanket Module (TBM) for testing in ITER (International Thermo nuclear Experimental Reactor). The Indian TBM concept is a Lead-Lithium cooled Ceramic Breeder (LLCB), which utilizes lead-lithium eutectic alloy (LLE) as tritium breeder, neutron multiplier and coolant. The first wall facing the plasma is cooled by helium gas. In preparation of the regulatory safety files of ITER-TBM, a number of off-normal event sequences have been postulated. Thermal hydraulic safety analyses of the TBM system will be carried out with the system code RELAP/SCDAPSIM/MOD4.0 which was initially designed to predict the behavior of light water reactor systems during normal and accidental conditions. In order to analyze some of the postulated off-normal events, there is the need to simulate the mixing of Helium and Lead-Lithium fluids. The Technical University of Catalonia is cooperating with IPR to implement the necessary changes in the code to allow for the mixing of helium and liquid metal. In the present study, the RELAP/SCDAPSIM/MOD4 two-phase flow 6-equations structure has been modified to allow for the mixture of LLE in the liquid phase with dry Helium in the gas phase. Practically obtaining a two-fluid 6-equation model where each fluid is simulated with a set of energy, mass and momentum balance equations. A preliminary flow regime map for LLE and helium flow has been developed on the basis of numerical simulations with the OpenFOAM CFD toolkit. The new code modifications have been verified for vertical and horizontal configurations. (Author)

Convective mixing in helium white dwarfs

International Nuclear Information System (INIS)

Vauclair, G.; Fontaine, G.

1979-01-01

The conditions under which convective mixing episodes take place between the helium envelopes and the underlying carbon layers in helium-rich white dwarfs are investigated. It is found that, for essentially any value of the initial helium content less than the maximum mass a helium convection zone can have, mixing does occur, and leads, in the vast majority of cases, to an almost pure carbon superficial composition. Mixing products that show only traces of carbon while retaining helium-dominated envelopes are possible only if the initial helium content is quite close to the maximum possible mass of the helium convection zone. In the presence of turbulence, this restriction could be relaxed, however, and the helium-rich lambda4670 stars may possibly be explained in this fashion

Friendly fermions of helium-three

International Nuclear Information System (INIS)

Leggatt, T.

1976-01-01

The importance of helium in showing up the effects of atomic indistinguishability and as a material by which to test some of the most fundamental principles of quantum mechanics is discussed. Helium not only remains liquid down to zero temperature but of the two isotopes helium-three has intrinsic spin 1/2 and should therefore obey the Pauli principle, while helium-four has spin zero and is expected to undergo Bose condensation. Helium-three becomes superfluid at temperatures of a few thousandths of a degree above absolute zero by the bulk liquid collecting its atoms into spinning pairs. There are three different superfluid phases, now conveniently called A, B and A 1 and each is characterised by a different behaviour of the spin and/or relative angular motion of the atoms composing the Cooper pairs. Problems surrounding the complicated physical system of helium-three are discussed. It is suggested that the combined coherence and directionality of superfluid helium-three should create some fascinating physics. (U.K.)

Advanced CSiC composites for high-temperature nuclear heat transport with helium, molten salts, and sulphur-iodine thermochemical hydrogen process fluids

International Nuclear Information System (INIS)

Peterson, P.F.; Forsberg, Ch.W.; Pickard, P.S.

2004-01-01

This paper discusses the use of liquid-silicon-impregnated (LSI) carbon-carbon composites for the development of compact and inexpensive heat exchangers, piping, vessels and pumps capable of operating in the temperature range of 800 to 1 100 deg C with high-pressure helium, molten fluoride salts, and process fluids for sulfur-iodine thermochemical hydrogen production. LSI composites have several potentially attractive features, including ability to maintain nearly full mechanical strength to temperatures approaching 1 400 deg C, inexpensive and commercially available fabrication materials, and the capability for simple forming, machining and joining of carbon-carbon performs, which permits the fabrication of highly complex component geometries. In the near term, these materials may prove to be attractive for use with a molten-salt intermediate loop for the demonstration of hydrogen production with a gas-cooled high temperature reactor. In the longer term, these materials could be attractive for use with the molten-salt cooled advanced high temperature reactor, molten salt reactors, and fusion power plants. (author)

Environmental pollution from working fluids of ORC processes; Umweltbelastung durch Arbeitsstoffe fuer organische Rankine-Prozesse

Energy Technology Data Exchange (ETDEWEB)

Hartmann, K.

2006-07-01

The contribution quantifies the negative environmental effects of the potential loss of working fluids and/or refrigerants and the positive environmental effect of power generation without working fluids. The TEWI (Total Equivalent Warming Impact)concept which is common in refrigeration and air conditioning was modified for ORc systems and was used for assessing the environmental effects of potential working fluids. (orig.)

Application of helium isotopes in shallow groundwaters for geothermal energy exploration in the Upper Rhine Graben

Energy Technology Data Exchange (ETDEWEB)

Freundt, Florian

2017-07-12

The helium isotope system is an established tool in hydrology for identifying mantle fluids in deep aquifers. This study applies the helium tracer system for the first time in shallow, unconfined aquifers of the Upper Rhine Graben. The Graben is a part of the Cenozoic Rift system of Western and Central Europe, a continental rift zone with unusually high geothermal gradients, making it an ideal region of Germany for geothermal energy development. The aim of this study is to develop a suite of natural groundwater tracers able to achieve a cost and effort reduction in geothermal prospection. The {sup 3}He/{sup 4}He-ratio is therefore applied, as part of a multi-tracer approach including {sup 3}H, δ{sup 18}O, δ{sup 2}H, δ{sup 13}C, {sup 14}C and {sup 222}Rn, to identify and locate fault zones with suitable permeabilities for power plant operation. Three target areas along the graben were studied, each located on one of the main fault lines. A mantle-derived helium signature could be identified and separated from tritiogenic helium in a shallow aquifer in the north-west of the Graben. The mixing component of mantle-derived fluid in the shallow groundwater is calculated to reach up to 5%, based on the analysis of the {sup 3}He/{sup 4}He isotope system. The employed method proves that the local permeability of the fault zone is high. The origin of the locally occurring upwelling of salinated water can be redetermined by the data.

Helium turbo-expander with an alternator

International Nuclear Information System (INIS)

Akiyama, Yoshitane

1980-01-01

Study was made on a helium turbo-expander, the heart of helium refrigerator systems, in order to develop a system which satisfies the required conditions. A helium turbo-expander with externally pressurized helium gas bearings at the temperature of liquid nitrogen and an alternator as a brake have been employed. The essential difference between a helium turbo-expander and a nitrogen turbo-expander was clarified. The gas bearing lubricated with nitrogen at room temperature and the gas bearing lubricated with helium at low temperature were tested. The flow rate of helium in a helium refrigerator for a large superconducting magnet is comparatively small, therefore a helium turbine must be small, but the standard for large turbine design can be applied to such small turbine. Using the alternator as a brake, the turbo-expander was easily controllable electrically. The prototype turbo-expander was made, and the liquefaction test with it and MHD power generation test were carried out. (Kako, I.)

Hydrogen and helium shell burning during white dwarf accretion

Science.gov (United States)

Cui, Xiao; Meng, Xiang-Cun; Han, Zhan-Wen

2018-05-01

Type Ia supernovae (SNe Ia) are believed to be thermonuclear explosions of carbon oxygen (CO) white dwarfs (WDs) with masses close to the Chandrasekhar mass limit. How a CO WD accretes matter and grows in mass to this limit is not well understood, hindering our understanding of SN Ia explosions and the reliability of using SNe Ia as a cosmological distance indicator. In this work, we employed the stellar evolution code MESA to simulate the accretion process of hydrogen-rich material onto a 1.0 M ⊙ CO WD at a high rate (over the Eddington limit) of 4.3 × 10‑7 M ⊙ yr‑1. The simulation demonstrates the characteristics of the double shell burning on top of the WD, with a hydrogen shell burning on top of a helium burning shell. The results show that helium shell burning is not steady (i.e. it flashes). Flashes from the helium shell are weaker than those in the case of accretion of helium-rich material onto a CO WD. The carbon to oxygen mass ratio resulting from the helium shell burning is higher than what was previously thought. Interestingly, the CO WD growing due to accretion has an outer part containing a small fraction of helium in addition to carbon and oxygen. The flashes become weaker and weaker as the accretion continues.

Helium retention in krypton ion pre-irradiated nanochannel W film

Science.gov (United States)

Qin, Wenjing; Ren, Feng; Zhang, Jian; Dong, Xiaonan; Feng, Yongjin; Wang, Hui; Tang, Jun; Cai, Guangxu; Wang, Yongqiang; Jiang, Changzhong

2018-02-01

Nanochannel tungsten (W) film is a promising candidate as an alternative to bulk W for use in fusion applications. In previous work it has been shown to have good radiation resistance under helium (He) irradiation. To further understand the influence of the irradiation-induced displacement cascade damage on helium retention behaviour in a fusion environment, in this work, nanochannel W film and bulk W were pre-irradiated by 800 keV Kr2+ ions to the fluence of 2.6  ×  1015 ions cm-2 and subsequently irradiated by 40 keV He+ ions to the fluence of 5  ×  1017 ions cm-2. The Kr2+ ion pre-irradiation greatly increases helium retention in the form of small clusters and retards the formation of large clusters. It can effectively inhibit surface helium blistering under high temperature annealing. Compared with bulk W, no cracks were found in the nanochannel W film post-irradiated by He+ ions at high fluence. The release of helium from the nanochannel W film is more than one order of magnitude higher than that of bulk W whether they are irradiated by single He+ ions or sequentially irradiated by Kr2+ and He+ ions. Moreover, swelling of the bulk W is more serious than that of the nanochannel film. Therefore, nanochannel W film has a higher radiation tolerance performance in the synergistic irradiation.

Modular helium reactor for non-electric applications

International Nuclear Information System (INIS)

Shenoy, A.

1997-01-01

The high temperature gas-cooled Modular Helium Reactor (MHR) is an advanced, high efficiency reactor system which can play a vital role in meeting the future energy needs of the world by contributing not only to the generation of electric power, but also the non-electric energy traditionally served by fossil fuels. This paper summarizes work done over 20 years, by several people at General Atomics, how the Modular Helium Reactor can be integrated to provide different non-electric applications during Process Steam/Cogeneration for industrial application, Process Heat for transportation fuel development and Hydrogen Production for various energy applications. The MHR integrates favorably into present petrochemical and primary metal process industries, heavy oil recovery, and future shale oil recovery and synfuel processes. The technical fit of the Process Steam/Cogeneration Modular Helium Reactor (PS/C-MHR) into these processes is excellent, since it can supply the required quantity and high quality of steam without fossil superheating. 12 refs, 25 figs, 2 tabs

High temperature embrittlement of metals by helium

International Nuclear Information System (INIS)

Schroeder, H.

1983-01-01

The present knowledge of the influence of helium on the high temperature mechanical properties of metals to be used as structural materials in fast fission and in future fusion reactors is reviewed. A wealth of experimental data has been obtained by many different experimental techniques, on many different alloys, and on different properties. This review is mostly concentrated on the behaviour of austenitic alloys -especially austenitic stainless steels, for which the data base is by far the largest - and gives only a few examples of special bcc alloys. The effect of the helium embrittlement on the different properties - tensile, fatigue and, with special emphasis, creep - is demonstrated by representative results. A comparison between data obtained from in-pile (-beam) experiments and from post-irradiation (-implantation) experiments, respectively, is presented. Theoretical models to describe the observed phenomena are briefly outlined and some suggestions are made for future work to resolve uncertainties and differences between our experimental knowledge and theoretical understanding of high temperature helium embrittlement. (author)

Helium in inert matrix dispersion fuels

International Nuclear Information System (INIS)

Veen, A. van; Konings, R.J.M.; Fedorov, A.V.

2003-01-01

The behaviour of helium, an important decay product in the transmutation chains of actinides, in dispersion-type inert matrix fuels is discussed. A phenomenological description of its accumulation and release in CERCER and CERMET fuel is given. A summary of recent He-implantation studies with inert matrix metal oxides (ZrO 2 , MgAl 2 O 4 , MgO and Al 2 O 3 ) is presented. A general picture is that for high helium concentrations helium and vacancy defects form helium clusters which convert into over-pressurized bubbles. At elevated temperature helium is released from the bubbles. On some occasions thermal stable nano-cavities or nano-pores remain. On the basis of these results the consequences for helium induced swelling and helium storage in oxide matrices kept at 800-1000 deg. C will be discussed. In addition, results of He-implantation studies for metal matrices (W, Mo, Nb and V alloys) will be presented. Introduction of helium in metals at elevated temperatures leads to clustering of helium to bubbles. When operational temperatures are higher than 0.5 melting temperature, swelling and helium embrittlement might occur

Operating Manual of Helium Refrigerator (Rev. 2)

Energy Technology Data Exchange (ETDEWEB)

Song, K.M.; Son, S.H.; Kim, K.S.; Lee, S.K.; Kim, M.S. [Korea Electric Power Research Institute, Taejon (Korea)

2002-07-01

A helium refrigerator was installed as a supplier of 20K cold helium to the cryogenic distillation system of WTRF pilot plant. The operating procedures of the helium refrigerator, helium compressor and auxiliary apparatus are described for the safety and efficient operation in this manual. The function of the helium refrigerator is to remove the impurities from the compressed helium of about 250psig, to cool down the helium from ambient temperature to 20K through the heat exchanger and expansion engine and to transfer the cold helium to the cryogenic distillation system. For the smoothly operation of helium refrigerator, the preparation, the start-up, the cool-down and the shut-down of the helium refrigerator are described in this operating manual. (author). 3 refs., 14 tabs.

Thermal optimization of the helium-cooled power leads for the SSC

International Nuclear Information System (INIS)

Demko, J.A.; Schiesser, W.E.; Carcagno, R.; McAshan, M.; McConeghy, R.

1992-01-01

The optimum thermal design of the power leads for the Superconducting Super Collider (SSC) will minimize the amount of Carnot work (which is a combination of refrigeration and liquefaction work) required. This optimization can be accomplished by the judicious selection of lead length and diameter. Even though an optimum set of dimensions is found, the final design must satisfy other physical constraints such as maximum allowable heat leak and helium vapor mass flow rate. A set of corresponding lengths and diameters has been determined that meets these requirements for the helium vapor-cooled, spiral-fin power lead design of the SSC. Early efforts by McFee and Mallon investigated optimizing power leads for cryogenic applications with no convection cooling. Later designs utilized the boiled-off helium vapor to cool the lead. One notable design for currents up to several thousand amps is presented by Efferson based on a series of recommendations discussed by Deiness. Buyanov presents many theoretical models and design formulae but does not demonstrate an approach to thermally optimizing the design of a vapor-cooled lead. In this study, a detailed numerical thermal model of a power lead design for the SSC has been developed. It was adapted from the dynamic model developed by Schiesser. This model was used to determine the optimum dimensions that minimize the Carnot refrigeration and liquefaction work due to the leads. Since the SSC leads will be cooled by supercritical helium, the flow of vapor is regulated by a control valve. These leads include a superconducting portion at the cold end. All of the material properties in the model are functions of temperature, and for the helium are functions of pressure and temperature. No pressure drop calculations were performed as part of this analysis. The diameter that minimizes the Carnot work was determined for four different lengths at a design current of 6600 amps

A new approach to systematic uncertainties and self-consistency in helium abundance determinations

International Nuclear Information System (INIS)

Aver, Erik; Olive, Keith A.; Skillman, Evan D.

2010-01-01

Tests of big bang nucleosynthesis and early universe cosmology require precision measurements for helium abundance determinations. However, efforts to determine the primordial helium abundance via observations of metal poor H II regions have been limited by significant uncertainties (compared with the value inferred from BBN theory using the CMB determined value of the baryon density). This work builds upon previous work by providing an updated and extended program in evaluating these uncertainties. Procedural consistency is achieved by integrating the hydrogen based reddening correction with the helium based abundance calculation, i.e., all physical parameters are solved for simultaneously. We include new atomic data for helium recombination and collisional emission based upon recent work by Porter \\etal and wavelength dependent corrections to underlying absorption are investigated. The set of physical parameters has been expanded here to include the effects of neutral hydrogen collisional emission. It is noted that Hγ and Hδ allow better isolation of the collisional effects from the reddening. Because of a degeneracy between the solutions for density and temperature, the precision of the helium abundance determinations is limited. Also, at lower temperatures (T ∼ p as 0.2561 ± 0.0108, in broad agreement with the WMAP result. Alternatively, a simple average of the data yields Y p 0.2566 ± 0.0028. Tests with synthetic data show a potential for distinct improvement, via removal of underlying absorption, using higher resolution spectra. A small bias in the abundance determination can be reduced significantly and the calculated helium abundance error can be reduced by ∼ 25%

Dynamics of vortex assisted metal condensation in superfluid helium.

Science.gov (United States)

Popov, Evgeny; Mammetkuliyev, Muhammet; Eloranta, Jussi

2013-05-28

Laser ablation of copper and silver targets immersed in bulk normal and superfluid (4)He was studied through time-resolved shadowgraph photography. In normal fluid, only a sub-millimeter cavitation bubble is created and immediate formation of metal clusters is observed within a few hundred microseconds. The metal clusters remain spatially tightly focused up to 15 ms, and it is proposed that this observation may find applications in particle image velocimetry. In superfluid helium, the cavitation bubble formation process is distinctly different from the normal fluid. Due to the high thermal conductivity and an apparent lag in the breakdown of superfluidity, about 20% of the laser pulse energy was transferred directly into the liquid and a large gas bubble, up to several millimeters depending on laser pulse energy, is created. The internal temperature of the gas bubble is estimated to exceed 9 K and the following bubble cool down period therefore includes two separate phase transitions: gas-normal liquid and normal liquid-superfluid. The last stage of the cool down process was assigned to the superfluid lambda transition where a sudden formation of large metal clusters is observed. This is attributed to high vorticity created in the volume where the gas bubble previously resided. As shown by theoretical bosonic density functional theory calculations, quantized vortices can trap atoms and dimers efficiently, exhibiting static binding energies up to 22 K. This, combined with hydrodynamic Bernoulli attraction, yields total binding energies as high as 35 K. For larger clusters, the static binding energy increases as a function of the volume occupied in the liquid to minimize the surface tension energy. For heliophobic species an energy barrier develops as a function of the cluster size, whereas heliophilics show barrierless entry into vortices. The present theoretical and experimental observations are used to rationalize the previously reported metal nanowire assembly in

Behavior of helium gas atoms and bubbles in low activation 9Cr martensitic steels

Science.gov (United States)

Hasegawa, Akira; Shiraishi, Haruki; Matsui, Hideki; Abe, Katsunori

1994-09-01

The behavior of helium-gas release from helium-implanted 9Cr martensitic steels (500 appm implanted at 873 K) during tensile testing at 873 K was studied. Modified 9Cr-1Mo, low-activation 9Cr-2W and 9Cr-0.5V were investigated. Cold-worked AISI 316 austenitic stainless steel was also investigated as a reference which was susceptible helium embrittlement at high temperature. A helium release peak was observed at the moment of rupture in all the specimens. The total quantity of helium released from these 9Cr steels was in the same range but smaller than that of 316CW steel. Helium gas in the 9Cr steels should be considered to remain in the matrix at their lath-packets even if deformed at 873 K. This is the reason why the martensitic steels have high resistance to helium embrittlement.

Behavior of helium gas atoms and bubbles in low activation 9Cr martensitic steels

International Nuclear Information System (INIS)

Hasegawa, Akira; Shiraishi, Haruki; Matsui, Hideki; Abe, Katsunori

1994-01-01

The behavior of helium-gas release from helium-implanted 9Cr martensitic steels (500 appm implanted at 873 K) during tensile testing at 873 K was studied. Modified 9Cr-1Mo, low-activation 9Cr-2W and 9Cr-0.5V were investigated. Cold-worked AISI 316 austenitic stainless steel was also investigated as a reference which was susceptible helium embrittlement at high temperature. A helium release peak was observed at the moment of rupture in all the specimens. The total quantity of helium released from these 9Cr steels was in the same range but smaller than that of 316CW steel. Helium gas in the 9Cr steels should be considered to remain in the matrix at their lath-packets even if deformed at 873 K. This is the reason why the martensitic steels have high resistance to helium embrittlement. ((orig.))

Effect of helium irradiation on fracture modes

International Nuclear Information System (INIS)

Hanamura, T.; Jesser, W.A.

1982-01-01

The objective of this work is to determine the crack opening mode during in-situ HVEM tensile testing and how it is influenced by test temperature and helium irradiation. Most cracks were mixed mode I and II. However, between 250 0 C and room temperature the effect of helium irradiation is to increase the amount of mode I crack propagation. Mode II crack opening was observed as grain boundary sliding initiated by a predominantly mode I crack steeply intersecting the grain boundary. Mode II crack opening was absent in irradiated specimens tested between 250 0 C and room temperature, but could be restored by a post irradiation anneal

Relation between the conditions of helium ion implantation and helium void equilibrium parameters

International Nuclear Information System (INIS)

Neklyudov, I.M.; Rybalko, V.F.; Ruzhitskij, V.V.; Tolstolutskaya, G.D.

1981-01-01

The conditions of helium thermodynamic equilibrium in a system of voids produced by helium ion bombardment of a metal sample are studied. As an initial equation for description of the equilibrium the Clapeyron equation was used. The equation is obtained relating basic parameters of helium voids (average diameter and density) to irradiation parameters (dose, ion energy (straggling)) and properties of the metal (surface tension coefficient, yield strength). Comparison of the calculations with experimental data on helium in nickel found in literature shows that the equation yields satisfactory resutls for the dose range 1.10 16 -1x10 17 cm -2 and temperatures T [ru

Leak-tightness assessment of demountable joints for the super fluid helium system of the CERN Large Hadron Collider (LHC)

International Nuclear Information System (INIS)

Brunet, J.C.; Poncet, A.; Trilhe, P.

1994-01-01

The future high energy accelerator LHC presently considered at CERN, will make heavy use of demountable cryogenic joints operating at superfluid helium temperatures (1.8 K). These joints will be required for connecting the cryomagnets to their feeding lines, helium safety valves to cold masses, both on their measuring benches and eventually in their final installation set-up. The very large size of the future machine and, consequently, the large number of cryogenic joints imply that their reliability in leak tightness be very high, in particular after extreme loading conditions such as the high helium pressures resulting from superconducting magnet quenches. For these reasons, a test set-up has been especially built at CERN to reproduce these conditions, and to assess the leak tightness reliability of commercially available joints. A description of the facility is presented, together with the first test results

Evaluation of a solar-powered organic Rankine cycle using dry organic working fluids

Directory of Open Access Journals (Sweden)

Emily Spayde

2015-12-01

Full Text Available This paper presents a model to evaluate the performance of a solar-powered organic Rankine cycle (ORC. The system was evaluated in Jackson, MS, using five dry organic working fluids, R218, R227ea, R236ea, R236fa, and RC318. The purpose of this study is to investigate how hourly temperature change affects the electricity production and exergy destruction rates of the solar ORC, and to determine the effect of the working fluid on the proposed system. The system was also evaluated in Tucson, AZ, to investigate the effect of average hourly outdoor temperatures on its performance. The potential of the system to reduce primary energy consumption and carbon dioxide emissions is also investigated. A parametric analysis to determine how temperature and pressure of the organic working fluid, the solar collector area, and the turbine efficiency affect the electricity production is performed. Results show that the ORC produces the most electricity during the middle of the day, when the temperatures are the highest and when the solar collectors have the highest efficiency. Also, R-236ea is the working fluid that shows the best performance of the evaluated fluids. An economic analysis was performed to determine the capital cost available for the proposed system.

Performance analysis and binary working fluid selection of combined flash-binary geothermal cycle

International Nuclear Information System (INIS)

Zeyghami, Mehdi

2015-01-01

Performance of the combined flash-binary geothermal power cycle for geofluid temperatures between 150 and 250 °C is studied. A thermodynamic model is developed, and the suitable binary working fluids for different geofluid temperatures are identified from a list of thirty working fluid candidates, consisting environmental friendly refrigerants and hydrocarbons. The overall system exergy destruction and Vapor Expansion Ratio across the binary cycle turbine are selected as key performance indicators. The results show that for low-temperature heat sources using refrigerants as binary working fluids result in higher overall cycle efficiency and for medium and high-temperature resources, hydrocarbons are more suitable. For combined flash-binary cycle, secondary working fluids; R-152a, Butane and Cis-butane show the best performances at geofluid temperatures 150, 200 and 250 °C respectively. The overall second law efficiency is calculated as high as 0.48, 0.55 and 0.58 for geofluid temperatures equal 150, 200 and 250 °C respectively. The flash separator pressure found to has important effects on cycle operation and performance. Separator pressure dictates the work production share of steam and binary parts of the system. And there is an optimal separator pressure at which overall exergy destruction of the cycle achieves its minimum value. - Highlights: • Performance of the combined flash-binary geothermal cycle is investigated. • Thirty different fluids are screened to find the most suitable ORC working fluid. • Optimum cycle operation conditions presented for geofluids between 150 °C and 250 °C. • Refrigerants are more suitable for the ORC at geothermal sources temperature ≤200 °C. • Hydrocarbons are more suitable for the ORC at geothermal sources temperature >200 °C

Cooling with Superfluid Helium

Energy Technology Data Exchange (ETDEWEB)

Lebrun, P; Tavian, L [European Organization for Nuclear Research, Geneva (Switzerland)

2014-07-01

The technical properties of helium II (‘superfluid’ helium) are presented in view of its applications to the cooling of superconducting devices, particularly in particle accelerators. Cooling schemes are discussed in terms of heat transfer performance and limitations. Large-capacity refrigeration techniques below 2 K are reviewed, with regard to thermodynamic cycles as well as process machinery. Examples drawn from existing or planned projects illustrate the presentation. Keywords: superfluid helium, cryogenics.

Large scale particle image velocimetry with helium filled soap bubbles

Energy Technology Data Exchange (ETDEWEB)

Bosbach, Johannes; Kuehn, Matthias; Wagner, Claus [German Aerospace Center (DLR), Institute of Aerodynamics and Flow Technology, Goettingen (Germany)

2009-03-15

The application of particle image velocimetry (PIV) to measurement of flows on large scales is a challenging necessity especially for the investigation of convective air flows. Combining helium filled soap bubbles as tracer particles with high power quality switched solid state lasers as light sources allows conducting PIV on scales of the order of several square meters. The technique was applied to mixed convection in a full scale double aisle aircraft cabin mock-up for validation of computational fluid dynamics simulations. (orig.)

Large scale particle image velocimetry with helium filled soap bubbles

Science.gov (United States)

Bosbach, Johannes; Kühn, Matthias; Wagner, Claus

2009-03-01

The application of Particle Image Velocimetry (PIV) to measurement of flows on large scales is a challenging necessity especially for the investigation of convective air flows. Combining helium filled soap bubbles as tracer particles with high power quality switched solid state lasers as light sources allows conducting PIV on scales of the order of several square meters. The technique was applied to mixed convection in a full scale double aisle aircraft cabin mock-up for validation of Computational Fluid Dynamics simulations.

Working fluid charge oriented off-design modeling of a small scale Organic Rankine Cycle system

International Nuclear Information System (INIS)

Liu, Liuchen; Zhu, Tong; Ma, Jiacheng

2017-01-01

Highlights: • Organic Rankine Cycle model considering working fluid charge has been established. • Overall solution algorithm of system off-design performance is proposed. • Variation trend of different zones in both heat exchangers can be observed. • Optimal working fluid charge volume for different output work has been estimated. - Abstract: Organic Rankine Cycle system is one of the most widely used technique for low-grade waste heat recovery. Developing of dynamic Organic Rankine Cycle models played an increasingly important part in system performance prediction. The present paper developed a working fluid charge oriented model for an small scale Organic Rankine Cycle to calculate the theoretical value of working fluid charge level for the system under rated condition. The two heat exchangers are divided into three different zones and related heat transfer correlations are employed to estimate the length variation of each zones. Steady state models have been applied to describe the performance of pump and expander. Afterwards, an overall solution algorithm based on the established model has been proposed in order to exact simulate the system’s off-design performance. Additionally, the impact of different working fluid charge volumes has also been discussed. Simulation results clearly shows the variation trend of different zones in both heat exchangers, as well as the variation trend of system operating parameters under various expander output work. Furthermore, the highest thermal efficiency can be reached 6.37% under rated conditions with a working fluid charge volume of 34.6 kg.

Helium supply demand in future years

International Nuclear Information System (INIS)

Laverick, C.

1975-01-01

Adequate helium will be available to the year 2000 AD to meet anticipated helium demands for present day applications and the development of new superconducting technologies of potential importance to the nation. It is almost certain that there will not be enough helium at acceptable financial and energy cost after the turn of the century to meet the needs of the many promising helium based technologies now under development. Serious consideration should be given to establishing priorities in development and application based upon their relative value to the country. In the first half of the next century, three ways of estimating helium demand lead to cumulative ranges of from 75 to 125 Gcf (economic study), 89 to 470 Gcf (projected national energy growth rates) and 154 to 328 Gcf (needs for new technologies). These needs contrast with estimated helium resources in natural gas after 2000 AD which may be as low as 10 or 126 Gcf depending upon how the federal helium program is managed and the nation's natural gas resources are utilized. The technological and financial return on a modest national investment in further helium storage and a rational long term helium program promises to be considerable

Tritium Decay Helium-3 Effects in Tungsten

Energy Technology Data Exchange (ETDEWEB)

Shimada, M. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Merrill, B. J. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2016-06-01

retention in helium-3 bubble. This paper reports the initial experimental observation of tritium-decay helium-3 in tungsten exposed to deuterium/tritium plasma along with electron microscope analysis and also discusses a Tritium Migration Analysis Program (TMAP) analysis of tritium-decay helium-3 effects on tritium retention in tungsten for DEMO and future fusion reactor. [1] Y. Hatano, et.al., Nucl. Fusion 53 (2013) 073006 [2] M. Shimada, et.al., Nucl. Fusion 55 (2015) 013008 [3] M. Sawan, Fus. Sci. Technol. 66 (2014) 272 [4] T. Otsuka, Fus. Sci. Technol. 60 (2011) 1539 This work was prepared for the U.S. Department of Energy, Office of Fusion Energy Sciences, under the DOE Idaho Field Office contract number DE-AC07-05ID14517.

The impact of internal longitudinal fins in parabolic trough collectors operating with gases

International Nuclear Information System (INIS)

Bellos, Evangelos; Tzivanidis, Christos; Daniil, Ilias; Antonopoulos, Kimon A.

2017-01-01

Highlights: • In this study, the impact of internal fins in PTC operating with gases is presented. • Air, helium and CO_2 are tested in smooth absorber and with fins of 5–10 mm and 15 mm. • Greater fin length leads to higher thermal efficiency and 10 mm is the optimum length exergetically. • Helium is the best working fluid exergetically, with CO_2 and air to follow. • Up to 290 °C, helium performs better energetically, while CO_2 in higher temperatures. - Abstract: In this study, the use of internal fins in parabolic trough collectors operating with gas working fluids is examined. Air, helium and carbon dioxide are the investigated working fluids, while Eurotrough ET-150 is the examined solar collector. The design and the simulation of this solar collector are performed with the commercial software Solidworks Flow Simulation. The internal fins lead to higher thermal efficiency but also to higher pressure losses; something very important for the solar fields of Concentrated Power Plants. Thus, the collector is examined energetically and exergetically in order to take into account the increase in the useful output with the simultaneous greater need of pumping power. Various fin lengths are examined and finally the fin of 10 mm was proved to be the most appropriate exergetically. In working fluid comparison, helium is the most efficient working fluid exergetically for all the examined cases. In the thermal efficiency comparison, helium performs better up to 290 °C, while carbon dioxide is the best choice in higher temperature levels. Moreover, the optimum mass flow rate for the helium was proved to be 0.03 kg/s and for the other working fluids the value of 0.015 kg/s seems to lead to the most satisfying results.

Molecular dynamics simulations of the diffusion and coalescence of helium in tungsten

International Nuclear Information System (INIS)

Zhou, Y.L.; Wang, J.; Hou, Q.; Deng, A.H.

2014-01-01

Molecular dynamics (MD) simulations are performed on the diffusion and coalescence of helium in tungsten. A new method for determining the effective capture radii (ECRs) and the dissociation energies of helium-related defects is proposed in this work. It is observed that the ECR of an interstitial helium atom trapping helium interstitials (denoted as He–He n , n = 1–3) decreases with increasing temperature, except for He–He 2 at T n for helium clusters are also investigated. He 2 migrates more quickly than a single He atom does at T 2 changes at higher temperatures. Another counterintuitive observation is that D 5 > D 3 > D 4 at T 5 . The Arrhenius relation describes the diffusion of He n well in the temperature range from 300 K to 550 K, whereas the diffusion is not a standard thermally activated process at higher temperatures. Taken together, these results help elucidate the initial stage of helium bubble formation in tungsten as well as the requirements of long-term evolution methods such as KMC or RT models

Surface electrons of helium films

International Nuclear Information System (INIS)

Studart, N.; Hipolito, O.

1986-01-01

Theoretical calculations of some properties of two-dimensional electrons on a liquid helium film adsorbed on a solid substrate are reviewed. We describe the spectrum of electron bound states on bulk helium as well on helium films. The correlational properties, such as the structure factor and correlation energy, are determined as functions of the film thickness for different types of substrates in the framework of a Generalized Random-Phase Approximation. The collective excitations of this system are also described. The results for electrons on the surface of thin films and bulk helium are easily obtained. we examine the electron interaction with the excitations of the liquid helium surface resulting in a new polaron state, which was observed very recently. The ground state energy and the effective mass of this polaron are determined by using the path-integral formalism and unitary-transformation method. Recent speculations about the phase diagram of electrons on the helium film are also discussed. (Author) [pt

Laser Induced Fluorescence of Helium Ions in a Helicon Plasma

Science.gov (United States)

Compton, C. S.; Biloui, C.; Hardin, R. A.; Keesee, A. M.; Scime, E. E.; Boivin, R.

2003-10-01

The lack of a suitable Laser Induced Fluorescence (LIF) scheme for helium ions at visible wavelengths has prevented LIF from being employed in helium plasmas for measurements of ion temperature and bulk ion flow speeds. In this work, we will discuss our attempts to perform LIF of helium ions in a helicon source plasma using an infrared, tunable diode laser operating at 1012.36 nm. The infrared transition corresponds to excitation from the n = 4 level (4f ^2F) to the n = 5 (5g ^2G) level of singly ionized helium and therefore requires substantial electron temperatures (> 10 eV) to maintain an adequate ion population in the n = 4 state. Calculations using a steady state coronal model predict that the n = 4 state population will be 25% larger than the n = 5 population for our experimental conditions. The fluorescence decay from the n = 5 (5f ^2F) level of singly ionized helium level to the n = 3 (3d ^2D) level at 320.31 nm is monitored as the diode laser is swept through 10 GHz around the 1012.36 nm line. Note that the fluorescence emission requires a collisionally coupled transition between two different n = 5 quantum states. We will also present measurements of the emission intensities of both the 1012.36 nm and the 320.31 nm lines as a function of source neutral pressure, rf power, and plasma density. This work supported by the U.S. DoE EPSCoR Lab Partnership Program.

Helium dilution refrigerator

International Nuclear Information System (INIS)

1973-01-01

A new system of continuous heat exchange for a helium dilution refrigerator is proposed. The 3 He effluent tube is concurrent with the affluent mixed helium tube in a vertical downward direction. Heat exchange efficiency is enhanced by placing in series a number of elements with an enlarged surface area

Sensitivity analysis of molecular design problem for the development of novel working fluids for power cycles

DEFF Research Database (Denmark)

Frutiger, Jerome; Abildskov, Jens; Sin, Gürkan

. Multi-criteria database search and Computer Aided Molecular Design (CAMD) can be applied to generate, test and evaluate promising pure component/mixture candidate as process fluids to help optimize cycle design and performance [1]. The problem formulation for the development of novel working fluids...... a certain working fluid property parameter on the performance of the power cycle, i.e. the net power output, can facilitate the identification key properties for working fluids. In that sense a sensitivity analysis of the different parameters is suggested in this work as a systematic method to efficiently...... technology to convert such waste heat sources into usable energy. So far the low-temperature heat is not utilized efficiently for electricity generation. To optimize the heat transfer process and the power generation, the influence of the working fluid, the cycle designs and the operating conditions is vital...

Analysis of thermal cycles and working fluids for power generation in space

International Nuclear Information System (INIS)

Tarlecki, Jason; Lior, Noam; Zhang Na

2007-01-01

Production of power in space for terrestrial use is of great interest in view of the rapidly rising power demand and its environmental impacts. Space also offers a very low temperature, making it a perfect heat sink for power plants, thus offering much higher efficiencies. This paper focuses on the evaluation and analysis of thermal Brayton, Ericsson and Rankine power cycles operating at space conditions on several appropriate working fluids. Under the examined conditions, the thermal efficiency of Brayton cycles reaches 63%, Ericsson 74%, and Rankine 85%. These efficiencies are significantly higher than those for the computed or real terrestrial cycles: by up to 45% for the Brayton, and 17% for the Ericsson; remarkably 44% for the Rankine cycle even when compared with the best terrestrial combined cycles. From the considered working fluids, the diatomic gases (N 2 and H 2 ) produce somewhat better efficiencies than the monatomic ones in the Brayton and Rankine cycles. The Rankine cycles require radiator areas that are larger by up to two orders of magnitude than those required for the Brayton and Ericsson cycles. The results of the analysis of the sensitivity of the cycle performance parameters to major parameters such as turbine inlet temperature and pressure ratio are presented, equations or examining the effects of fluid properties on the radiator area and pressure drop were developed, and the effects of the working fluid properties on cycle efficiency and on the power production per unit radiator area were explored to allow decisions on the optimal choice of working fluids

Apparatus to measure low level helium for neutron dosimetry

Energy Technology Data Exchange (ETDEWEB)

Ozaki, Shuji; Takao, Yoshiyuki; Muramasu, Masatomo; Hida, Tomoya; Sou, Hirofumi; Nakashima, Hideki [Kyushu Univ., Fukuoka (Japan); Kanda, Yukinori

1998-03-01

An apparatus to measure low level helium in a solid sample for neutron dosimetry in the practical use such as area monitoring in the long-term and reactor surveillance was reported. In our previous work, the helium atoms measurement system (HAMS) was developed. A sample was evaporated in the furnace and the released gas from the sample was analyzed with the mass spectrometer of the system to determine the amount of helium contained in it. The system has been improved to advance the lower helium measurement limit in a solid sample for its application to an area monitoring system. The mass of a solid is up to 100mg. Two important points should be considered to advance the lower limit. One was to produce a high quality vacuum in the system chamber for suppressing background gases during the sample measurement. The other important point was to detect very small output from the mass spectrometer. A pulse counting system was used to get high sensitivity in the mass 4 analyzing. (author)

A compact quadrupole ion filter for helium detection

International Nuclear Information System (INIS)

Pereira, E.B.

1981-01-01

A compact quadrupole ion filter was conceived and constructed for optimum performance at the mass four region of the mass spectra. It was primarely designed for geological applications in the measurements of helium of soil-gases. The whole ion filter structure is 15 cm long by 3.5 cm diameter, including ion source and collecting plate. The sensitivity to helium is of the order of 10 - 2 A.torr - 1 measured at a total pressure of 6x10 - 6 torr and resolution 6. The system can be easily adapted to work as a dynamic residual gas analyser for other purposes. (Author) [pt

Study and simulation of the behaviour under irradiation of helium in uranium dioxide; Etude et modelisation du comportement sous irradiation de l'helium dans le dioxyde d'uranium

Energy Technology Data Exchange (ETDEWEB)

Martin, G

2007-06-15

Large quantities of helium are produced from {alpha}-decay of actinides in nuclear fuels during its in-pile operating and its storage. It is important to understand the behaviour of helium in these matrix in order to well simulate the evolution and the resistance of the fuel element. During this thesis, we have used nuclear reaction analyses (NRA) to follow the evolution of the helium implanted in polycrystalline and monocrystalline uranium dioxide (UO{sub 2}). An experimental rig was developed to follow the on-line helium release in UO{sub 2} and the evolution of {sup 3}He profiles as a function of annealing temperature. An automated procedure taking into account the evolution of the depth resolution was developed. Analyses performed with a nuclear microprobe allowed to characterise the spatial distribution of helium at the grain scale and to study the influence of the sample microstructure on the helium migration. This work put into evidence the particular role of grain boundaries and irradiation defects in the helium release process. The analyse of experimental results with a diffusion model corroborates these interpretations. It allowed to determine quantitatively physical properties that characterise the helium behaviour in uranium dioxide (diffusion coefficient, activation energy..). (author)

A contemporary look at Hermann Hankel's 1861 pioneering work on Lagrangian fluid dynamics

Science.gov (United States)

Frisch, Uriel; Grimberg, Gérard; Villone, Barbara

2017-12-01

The present paper is a companion to the paper by Villone and Rampf (2017), titled "Hermann Hankel's On the general theory of motion of fluids, an essay including an English translation of the complete Preisschrift from 1861" together with connected documents [Eur. Phys. J. H 42, 557-609 (2017)]. Here we give a critical assessment of Hankel's work, which covers many important aspects of fluid dynamics considered from a Lagrangian-coordinates point of view: variational formulation in the spirit of Hamilton for elastic (barotropic) fluids, transport (we would now say Lie transport) of vorticity, the Lagrangian significance of Clebsch variables, etc. Hankel's work is also put in the perspective of previous and future work. Hence, the action spans about two centuries: from Lagrange's 1760-1761 Turin paper on variational approaches to mechanics and fluid mechanics problems to Arnold's 1966 founding paper on the geometrical/variational formulation of incompressible flow. The 22-year-old Hankel - who was to die 12 years later — emerges as a highly innovative master of mathematical fluid dynamics, fully deserving Riemann's assessment that his Preisschrift contains "all manner of good things."

The adsorption of helium atoms on small cationic gold clusters.

Science.gov (United States)

Goulart, Marcelo; Gatchell, Michael; Kranabetter, Lorenz; Kuhn, Martin; Martini, Paul; Gitzl, Norbert; Rainer, Manuel; Postler, Johannes; Scheier, Paul; Ellis, Andrew M

2018-04-04

Adducts formed between small gold cluster cations and helium atoms are reported for the first time. These binary ions, Aun+Hem, were produced by electron ionization of helium nanodroplets doped with neutral gold clusters and were detected using mass spectrometry. For a given value of n, the distribution of ions as a function of the number of added helium atoms, m, has been recorded. Peaks with anomalously high intensities, corresponding to so-called magic number ions, are identified and interpreted in terms of the geometric structures of the underlying Aun+ ions. These features can be accounted for by planar structures for Aun+ ions with n ≤ 7, with the addition of helium having no significant effect on the structures of the underlying gold cluster ions. According to ion mobility studies and some theoretical predictions, a 3-D structure is expected for Au8+. However, the findings for Au8+ in this work are more consistent with a planar structure.

Property Uncertainty Analysis and Methods for Optimal Working Fluids of Thermodynamic Cycles

DEFF Research Database (Denmark)

Frutiger, Jerome

in the context of an industrial organic Rankine cycle, used for the recovery of waste heat from an engine of a marine container ship. The study illustrates that the model structure is vital for the uncertainties of equations of state and suggests that uncertainty becomes a criterion (along with e.g. goodness......-of-fit or ease of use) for the selection of an equation of state for a specific application. Furthermore, two studies on the identification of suitable working fluids for thermodynamic cycles are presented. The first one selects and assesses working fluid candidates for an organic Rankine cycle system to recover......There is an increasing interest in recovering industrial waste heat at low tempera-tures (70-250◦C). Thermodynamic cycles, such as heat pumps or organic Rankine cycles, can recover this heat and transfer it to other process streams or convert it into electricity. The working fluid, circulating...

Prospects of the use of nanofluids as working fluids for organic Rankine cycle power systems

DEFF Research Database (Denmark)

Mondejar, Maria E.; Andreasen, Jesper G.; Regidor, Maria

2017-01-01

The search of novel working fluids for organic Rankine cycle power systems is driven by the recent regulations imposing additional phase-out schedules for substances with adverse environmental characteristics. Recently, nanofluids (i.e. colloidal suspensions of nanoparticles in fluids) have been...... suggested as potential working fluids for organic Rankine cycle power systems due to their enhanced thermal properties, potentially giving advantages with respect to the design of the components and the cycle performance. Nevertheless, a number of challenges concerning the use of nanofluids must...... the prospects of using nanofluids as working fluids for organic Rankine cycle power systems. As a preliminary study, nanofluids consisting of a homogenous and stable mixture of different nanoparticles types and a selected organic fluid are simulated on a case study organic Rankine cycle unit for waste heat...

Backscattered Helium Spectroscopy in the Helium Ion Microscope: Principles, Resolution and Applications

NARCIS (Netherlands)

van Gastel, Raoul; Hlawacek, G.; Dutta, S.; Poelsema, Bene

2015-01-01

We demonstrate the possibilities and limitations for microstructure characterization using backscattered particles from a sharply focused helium ion beam. The interaction of helium ions with matter enables the imaging, spectroscopic characterization, as well as the nanometer scale modification of

HeREF-2003: Helium Refrigeration Techniques

CERN Multimedia

2003-01-01

CERN Technical Training 2003: Learning for the LHC ! Theory, Technology, Maintenance and Control of Helium Refrigerators HeREF-2003 is a course in the framework of the 2002 Technical Training Programme, that will provide a complete introduction to Helium refrigeration, with a practical approach to theory, technology, maintenance and control of Helium refrigeration installations. Theoretical aspects and equations will be limited to a minimum. HeREF-2003 targets an audience of technicians and operators of Helium refrigeration plants at CERN, as well as physicists and engineers needing an overview of current Helium refrigeration techniques. HeREF-2003 will address, among other, issues related to component technology, installation maintenance, process control and Helium purity. A commented visit to a couple of CERN Helium refrigeration or liquefaction plants will also take place. Duration: 7 half days (4 mornings and 3 afternoons), 6-10 October, 2003 Cost per participant: 500.- CHF Language: Bilingual English...

HeREF-2003 : Helium Refrigeration Techniques

CERN Multimedia

2003-01-01

CERN Technical Training 2003: Learning for the LHC ! Theory, Technology, Maintenance and Control of Helium Refrigerators HeREF-2003 is a course in the framework of the 2002 Technical Training Programme, that will provide a complete introduction to Helium refrigeration, with a practical approach to theory, technology, maintenance and control of Helium refrigeration installations. Theoretical aspects and equations will be limited to a minimum. HeREF-2003 targets an audience of technicians and operators of Helium refrigeration plants at CERN, as well as physicists and engineers needing an overview of current Helium refrigeration techniques. HeREF-2003 will address, among other, issues related to component technology, installation maintenance, process control and Helium purity. A commented visit to a couple of CERN Helium refrigeration or liquefaction plants will also take place. • Duration: 7 half days (4 mornings and 3 afternoons), 6-10 October, 2003 • Cost per participant: 500.- CHF
...

ISO 15859 Propellant and Fluid Specifications: A Review and Comparison with Military and NASA Specifications

Science.gov (United States)

Greene, Ben; McClure, Mark B.; Baker, David L.

2006-01-01

This work presents an overview of the International Organization for Standardization (ISO) 15859 International Standard for Space Systems Fluid Characteristics, Sampling and Test Methods Parts 1 through 13 issued in June 2004. These standards establish requirements for fluid characteristics, sampling, and test methods for 13 fluids of concern to the propellant community and propellant characterization laboratories: oxygen, hydrogen, nitrogen, helium, nitrogen tetroxide, monomethylhydrazine, hydrazine, kerosene, argon, water, ammonia, carbon dioxide, and breathing air. A comparison of the fluid characteristics, sampling, and test methods required by the ISO standards to the current military and NASA specifications, which are in use at NASA facilities and elsewhere, is presented. Many ISO standards composition limits and other content agree with those found in the applicable parts of NASA SE-S-0073, NASA SSP 30573, military performance standards and details, and Compressed Gas Association (CGA) commodity specifications. The status of a current project managed at NASA Johnson Space Center White Sands Test Facility (WSTF) to rewrite these documents is discussed.

Working memory - not processing speed - mediates fluid intelligence deficits associated with attention deficit/hyperactivity disorder symptoms.

Science.gov (United States)

Brydges, Christopher R; Ozolnieks, Krista L; Roberts, Gareth

2017-09-01

Attention deficit/hyperactivity disorder (ADHD) is a psychological condition characterized by inattention and hyperactivity. Cognitive deficits are commonly observed in ADHD patients, including impaired working memory, processing speed, and fluid intelligence, the three of which are theorized to be closely associated with one another. In this study, we aimed to determine if decreased fluid intelligence was associated with ADHD, and was mediated by deficits in working memory and processing speed. This study tested 142 young adults from the general population on a range of working memory, processing speed, and fluid intelligence tasks, and an ADHD self-report symptoms questionnaire. Results showed that total and hyperactive ADHD symptoms correlated significantly and negatively with fluid intelligence, but this association was fully mediated by working memory. However, inattentive symptoms were not associated with fluid intelligence. Additionally, processing speed was not associated with ADHD symptoms at all, and was not uniquely predictive of fluid intelligence. The results provide implications for working memory training programs for ADHD patients, and highlight potential differences between the neuropsychological profiles of ADHD subtypes. © 2015 The British Psychological Society.

Mobility of hydrogen-helium clusters in tungsten studied by molecular dynamics

Energy Technology Data Exchange (ETDEWEB)

Grigorev, Petr, E-mail: grigorievpit@gmail.com [SCK-CEN, Nuclear Materials Science Institute, Boeretang 200, Mol, 2400 (Belgium); Ghent University, Applied Physics EA17 FUSION-DC, St.Pietersnieuwstraat, 41 B4, B-9000, Gent (Belgium); Department of Experimental Nuclear Physics K-89, Institute of Physics, Nanotechnologies, and Telecommunications, Peter the Great St.Petersburg Polytechnic University, St. Petersburg (Russian Federation); Terentyev, Dmitry; Bonny, Giovanni [SCK-CEN, Nuclear Materials Science Institute, Boeretang 200, Mol, 2400 (Belgium); Zhurkin, Evgeny E. [Department of Experimental Nuclear Physics K-89, Institute of Physics, Nanotechnologies, and Telecommunications, Peter the Great St.Petersburg Polytechnic University, St. Petersburg (Russian Federation); Oost, Guido van [Ghent University, Applied Physics EA17 FUSION-DC, St.Pietersnieuwstraat, 41 B4, B-9000, Gent (Belgium); Noterdaeme, Jean-Marie [Ghent University, Applied Physics EA17 FUSION-DC, St.Pietersnieuwstraat, 41 B4, B-9000, Gent (Belgium); Max-Planck-Institut für Plasmaphysik, Garching (Germany)

2016-06-15

Tungsten is a primary candidate material for plasma facing components in fusion reactors. Interaction of plasma components with the material is unavoidable and will lead to degradation of the performance and the lifetime of the in-vessel components. In order to gain better understanding the mechanisms driving the material degradation at atomic level, atomistic simulations are employed. In this work we study migration, stability and self-trapping properties of pure helium and mixed helium-hydrogen clusters in tungsten by means of molecular dynamics simulations. We test two versions of an embedded atom model interatomic potential by comparing it with ab initio data regarding the binding properties of He clusters. By analysing the trajectories of the clusters during molecular dynamics simulations at finite temperatures we obtain the diffusion parameters. The results show that the diffusivity of mixed clusters is significantly lower, than that of pure helium clusters. The latter suggest that the formation of mixed clusters during mixed hydrogen helium plasma exposure will affect the helium diffusivity in the material.

Neutron Irradiation Tests of Pressure Transducers in Liquid Helium

CERN Document Server

Amand, J F; Casas-Cubillos, J; Thermeau, J P

1999-01-01

The superconducting magnets of the future Large Hadron Collider (LHC) at CERN will operate in pressurised superfluid helium (1 bar, 1.9 K). About 500 pressure transducers will be placed in the liquid helium bath for monitoring the filling and the pressure transients after resistive transitions. Their precision must remain better than 100 mbar at pressures below 2 bar and better than 5% for higher pressures (up to 20 bar), with temperatures ranging from 1.8 K to 300 K. All the tested transducers are based on the same principle: the fluid or gas is separated from a sealed reference vacuum by an elastic membrane; its deformation indicates the pressure. The transducers will be exposed to high neutron fluence (2 kGy, 1014 n/cm2 per year) during the 20 years of machine operation. This irradiation may induce changes both on the membranes characteristics (leakage, modification of elasticity) and on gauges which measure their deformations. To investigate these effects and select the transducer to be used in the LHC, a...

Gas turbine modular helium reactor in cogeneration

International Nuclear Information System (INIS)

Leon de los Santos, G.

2009-10-01

This work carries out the thermal evaluation from the conversion of nuclear energy to electric power and process heat, through to implement an outline gas turbine modular helium reactor in cogeneration. Modeling and simulating with software Thermo flex of Thermo flow the performance parameters, based on a nuclear power plant constituted by an helium cooled reactor and helium gas turbine with three compression stages, two of inter cooling and one regeneration stage; more four heat recovery process, generating two pressure levels of overheat vapor, a pressure level of saturated vapor and one of hot water, with energetic characteristics to be able to give supply to a very wide gamma of industrial processes. Obtaining a relationship heat electricity of 0.52 and efficiency of net cogeneration of 54.28%, 70.2 MW net electric, 36.6 MW net thermal with 35% of condensed return to 30 C; for a supplied power by reactor of 196.7 MW; and with conditions in advanced gas turbine of 850 C and 7.06 Mpa, assembly in a shaft, inter cooling and heat recovery in cogeneration. (Author)

A dynamic model for helium core heat exchangers

International Nuclear Information System (INIS)

Schiesser, W.E.; Shih, H.J.; Hartozog, D.G.; Herron, D.M.; Nahmias, D.; Stuber, W.G.; Hindmarsh, A.C.

1990-04-01

To meet the helium (He) requirements of the superconducting supercollider (SSC), the cryogenic plants must be able to respond to time-varying loads. Thus the design and simulation of the cryogenic plants requires dynamic models of their principal components, and in particular, the core heat exchangers. In this paper, we detail the derivation and computer implementation of a model for core heat exchangers consisting of three partial differential equations (PDES) for each fluid stream (the continuity, energy and momentum balances for the He), and one PDE for each parting sheet (the energy balance for the parting sheet metal); the PDEs have time and axial position along the exchanger as independent variables. The computer code can accommodate any number of fluid streams and parting sheets in an adiabatic group. Features of the code include: rigorous or approximate thermodynamic properties for He, upwind and downwind approximation of the PDE spatial derivatives, and sparse matrix time integration. The outputs from the code include the time-dependent axial profiles of the fluid He mass flux, density, pressure, temperature, internal energy and enthalpy. The code is written in transportable Fortran 77, and can therefore be executed on essentially any computer

A dynamic model for helium core heat exchangers

International Nuclear Information System (INIS)

Schiesser, W.E.; Shih, H.J.; Hartzog, D.G.; Herron, D.M.; Nahmias, D.; Stuber, W.G.; Hindmarsh, A.C.

1990-01-01

To meet the helium (He) requirements of the superconducting supercollider (SSC), the cryogenic plants must be able to respond to time-varying loads. Thus the design and simulation of the cryogenic plants requires dynamic models of their principal components, and in particular, the core heat exchangers. In this paper, we detail the derivation and computer implementation of a model for core heat exchangers consisting of three partial differential equations (PDEs) for each fluid stream (the continuity, energy and momentum balances for the He), and one PDE for each parting sheet (the energy balance for the parting sheet metal); the PDEs have time and axial position along the exchanger as independent variables. The computer code can accommodate any number of fluid streams and parting sheets in an adiabatic group. Features of the code include: rigorous or approximate thermodynamic properties for He, upwind and downwind approximation of the PDE spatial derivatives, and sparse matrix time integration. The outputs from the code include the time-dependent axial profiles of the fluid He mass flux, density, pressure, temperature, internal energy and enthalpy. The code is written in transportable Fortran 77, and can therefore be executed on essentially any computer. 10 refs., 10 figs

Potential of organic Rankine cycle technology in India: Working fluid selection and feasibility study

International Nuclear Information System (INIS)

Sarkar, Jahar; Bhattacharyya, Souvik

2015-01-01

India has great potential to employ the ORC (organic Rankine cycle) technology for conversion of low temperature waste heat and renewable energy. In this study, available waste heat and relevant renewable heat sources in India are reviewed and suitable working fluids for ORC have been selected based on operational, environmental and safety criteria. A feasibility study and comparison of selected fluids for ORC is also presented for Indian climates along with discussions on component, operation and cost related aspects. A comprehensive review on available heat sources and sinks shows that India has plenty of waste heat and renewable energy sources for electricity generation by means of ORC; however, condenser operation may be challenging due to wide ambient temperature variation. Appropriate performance comparison among selected working fluids shows that ammonia is the best fluid in terms of net power generation and compactness of turbo-machineries, whereas n-Pentane is the best fluid in terms of thermal efficiency and heat exchanger compactness. Both are recommended as working fluids for ORC installations in India. The study reveals that there is a great opportunity to employ this technology in India provided we have to overcome some challenges related to component selection, finance and maintenance. - Highlights: • Available waste heat and renewable heat energies, and sinks in India are reviewed. • Suitable working fluids are selected by operational, environmental and safety criteria. • A feasibility study and comparison of selected fluids are presented for Indian climates. • Ammonia and n-Pentane are recommended for ORC installation in India. • Challenges related to plant component, operation and cost are discussed.

Helium localization around the microscopic impurities embedded to liquid helium

International Nuclear Information System (INIS)

Gordon, E.B.; Shestakov, A.F.

2000-01-01

The structure and properties of the environment round the impurity atoms (Im) embedded in liquid helium are considered. It is shown that there are two qualitatively different types of structure of the He atom layer next to Im - attraction and repulsion structures. For the center attraction structure (strong Im-He interaction) the Im-He separation is longer than the equilibrium one for the pair Im-He potential, and the density and localization of He atoms are higher than in the bulk. It this case the He atom content in the layer, n, is almost independent of applied pressure. In the repulsion structure realized for alkaline metal atoms the Im-He separation is shorter than the equilibrium one and the density is lower than in the helium bulk. At T approx 1 K occupied are several states with different n and their energies differ only by approx 0.1 K, an increase in pressure resulting in a considerable reduction of n. The optical and EPR spectra of the atoms embedded to liquid and solid helium are interpreted on the basis of the analysis carried out. A simple model is proposed to evaluate the helium surroundings characteristics from the experimental pressure dependences of atomic line shifts in the absorption and emission spectra. The attraction structures in 3 He - 4 He mixtures are suggested to be highly enriched by 4 He atoms which the repulsion structures - by 3 He atoms. a possibility for existence of phase transitions in helium shells surrounding impurity atoms is considered

Thermodynamic analysis of high-temperature regenerative organic Rankine cycles using siloxanes as working fluids

International Nuclear Information System (INIS)

Fernandez, F.J.; Prieto, M.M.; Suarez, I.

2011-01-01

A recent novel adjustment of the Span-Wagner equation of state for siloxanes, used as working fluids in high-temperature organic Rankine cycles, is applied in a mathematical model to solve cycles under several working conditions. The proposed scheme includes a thermo-oil intermediate heat circuit between the heat source and the organic Rankine cycle. Linear and cyclic siloxanes are assayed in saturated, superheated and supercritical cycles. The cycle includes an internal heat exchanger (regenerative cycle), although a non-regenerative scheme is also solved. In the first part of the study, a current of combustion gases cooled to close to their dew point temperature is taken as the reference heat source. In the second part, the outlet temperature of the heat source is varied over a wide range, determining appropriate fluids and schemes for each thermal level. Simple linear (MM, MDM) siloxanes in saturated regenerative schemes show good efficiencies and ensure thermal stability of the working fluid. -- Highlights: → Organic Rankine cycles with polymethylsiloxanes as working fluids were modelled. → The cycle scheme is regenerative and includes an intermediate heat transfer fluid. → The fluid properties were calculated by means of the Span-Wagner equation of state. → Vapour conditions to the expander and source thermal level were analysed. → Siloxanes MM, MDM and D 4 under saturated conditions were the best options.

Test of a cryogenic helium pump

International Nuclear Information System (INIS)

Lue, J.W.; Miller, J.R.; Walstrom, P.L.; Herz, W.

1981-01-01

The design of a cryogenic helium pump for circulating liquid helium in a magnet and the design of a test loop for measuring the pump performance in terms of mass flow vs pump head at various pump speeds are described. A commercial cryogenic helium pump was tested successfully. Despite flaws in the demountable connections, the piston pump itself has performed satisfactorily. A helium pump of this type is suitable for the use of flowing supercritical helium through Internally Cooled Superconductor (ICS) magnets. It has pumped supercritical helium up to 7.5 atm with a pump head up to 2.8 atm. The maximum mass flow rate obtained was about 16 g/s. Performance of the pump was degraded at lower pumping speeds

The design of the helium refrigerator for TORE SUPRA

International Nuclear Information System (INIS)

Gistau, G.M.; Claudet, G.

1984-01-01

The special cryogenic requirements of TORE SUPRA have called for novel solutions. Pumping the 1,75 K (13 mb) helium bath is achieved by the use of a pair of centrifugal pumps operating at very low temperature, backed up by liquid rings pumps at room temperature. Four oil-lubricated screw compressors mounted in series-parallel form the main cycle helium compression set. The Joule-Thomson expansion valve is replaced by a mechanical expansion engine working with a bi-phase exhaust. The control of the refrigeration system is entirely automatic

Impulse approximation in solid helium

International Nuclear Information System (INIS)

Glyde, H.R.

1985-01-01

The incoherent dynamic form factor S/sub i/(Q, ω) is evaluated in solid helium for comparison with the impulse approximation (IA). The purpose is to determine the Q values for which the IA is valid for systems such a helium where the atoms interact via a potential having a steeply repulsive but not infinite hard core. For 3 He, S/sub i/(Q, ω) is evaluated from first principles, beginning with the pair potential. The density of states g(ω) is evaluated using the self-consistent phonon theory and S/sub i/(Q,ω) is expressed in terms of g(ω). For solid 4 He resonable models of g(ω) using observed input parameters are used to evaluate S/sub i/(Q,ω). In both cases S/sub i/(Q, ω) is found to approach the impulse approximation S/sub IA/(Q, ω) closely for wave vector transfers Q> or approx. =20 A -1 . The difference between S/sub i/ and S/sub IA/, which is due to final state interactions of the scattering atom with the remainder of the atoms in the solid, is also predominantly antisymmetric in (ω-ω/sub R/), where ω/sub R/ is the recoil frequency. This suggests that the symmetrization procedure proposed by Sears to eliminate final state contributions should work well in solid helium

CFD Analysis for Hot Spot Fuel Temperature of Deep-Burn Modular Helium Reactor

International Nuclear Information System (INIS)

Tak, Nam Il; Jo, Chang Keun; Jun, Ji Su; Kim, Min Hwan; Venneri, Francesco

2009-01-01

As an alternative concept of a conventional transmutation using fast reactors, a deep-burn modular helium reactor (DB-MHR) concept has been proposed by General Atomics (GA). Kim and Venneri published an optimization study on the DB-MHR core in terms of nuclear design. The authors concluded that more concrete evaluations are necessary including thermo-fluid and safety analysis. The present paper describes the evaluation of the hot spot fuel temperature of the fuel assembly in the 600MWth DB-MHR core under full operating power conditions. Two types of fuel shuffling scheme (radial and axial hybrid shuffling and axial-only shuffling) are investigated. For accurate thermo-fluid analysis, the computational fluid dynamics (CFD) analysis has been performed on a 1/12 fuel assembly using the CFX code

Thermodynamic properties of cryogenic fluids

CERN Document Server

Leachman, Jacob; Lemmon, Eric; Penoncello, Steven

2017-01-01

This update to a classic reference text provides practising engineers and scientists with accurate thermophysical property data for cryogenic fluids. The equations for fifteen important cryogenic fluids are presented in a basic format, accompanied by pressure-enthalpy and temperature-entropy charts and tables of thermodynamic properties. It begins with a chapter introducing the thermodynamic relations and functional forms for equations of state, and goes on to describe the requirements for thermodynamic property formulations, needed for the complete definition of the thermodynamic properties of a fluid. The core of the book comprises extensive data tables and charts for the most commonly-encountered cryogenic fluids. This new edition sees significant updates to the data presented for air, argon, carbon monoxide, deuterium, ethane, helium, hydrogen, krypton, nitrogen and xenon. The book supports and complements NIST’s REFPROP - an interactive database and tool for the calculation of thermodynamic propertie...

Numerical Study on the Helium Flow Characteristics for Steam Generator Subsystem of HTR

International Nuclear Information System (INIS)

Ha, Jung Hoon; Ham, Jin Ki; Ki, Min-Hwan; Lee, Won Jae

2014-01-01

The High Temperature Reactor (HTR), one of the 4th generation reactors, utilizes helium as the primary coolant. A Steam Generator Subsystem (SGS) is installed to transfer heat from the primary coolant to feed water and subsequently produce steam so that it supplies electricity as well as process heat over a wide range. The SGS is composed of a helical heat exchanger, shrouds directing the flow of the shell side helium and support systems, which are located within the steam generator vessel. In this study, helium flow characteristics in the SGS were investigated at various operating conditions using Computational Fluid Dynamics (CFD). A full-scale 3-D model of the SGS was developed and the reynolds stress model with standard wall treatment was used as a turbulence model. The CFD result was compared to that of the concept design of the steam cycle modular helium reactor for the design verification of the SGS. From the CFD analysis, it was found that the primary coolant flow had non-uniform distribution while it passed the inlet in the helical heat exchanger. In order to make the uniform primary coolant flow uniform, a special type of screen was suggested in front of the helical heat exchanger. As a result, the overall design adequacy of the SGS has been evaluated. (author)

Focal depth measurement of scanning helium ion microscope

International Nuclear Information System (INIS)

Guo, Hongxuan; Itoh, Hiroshi; Wang, Chunmei; Zhang, Han; Fujita, Daisuke

2014-01-01

When facing the challenges of critical dimension measurement of complicated nanostructures, such as of the three dimension integrated circuit, characterization of the focal depth of microscopes is important. In this Letter, we developed a method for characterizing the focal depth of a scanning helium ion microscope (HIM) by using an atomic force microscope tip characterizer (ATC). The ATC was tilted in a sample chamber at an angle to the scanning plan. Secondary electron images (SEIs) were obtained at different positions of the ATC. The edge resolution of the SEIs shows the nominal diameters of the helium ion beam at different focal levels. With this method, the nominal shapes of the helium ion beams were obtained with different apertures. Our results show that a small aperture is necessary to get a high spatial resolution and high depth of field images with HIM. This work provides a method for characterizing and improving the performance of HIM.

Post-giant evolution of helium stars

International Nuclear Information System (INIS)

Schoenberner, D.

1977-01-01

Extremely hydrogen deficient stars (helium stars and R Coronae Borealis variables) are considered to be remnants of double shell source stars (of the asymptotic giant branch). The evolution of stars with a condensed C/O-core and a helium envelope is followed numerically from the red giant stage to the white dwarf domain, crossing the regions of R CrB- and helium stars (so far analyzed). They have typically masses M/M(sun) = 0.7 and luminosities log L/L(sun) = 4.1. The time for crossing the helium star domain is some 10 3 years. The corresponding times in the R CrB-region amounts up to several 10 4 years. The lower limit of the death rate of helium stars is estimated to be 4 x 10 -14 pc -3 yr -1 . This value is only a factor of ten lower than the birth rate of all non-DA white dwarfs. It is therefore possible that the helium stars are the precursors of helium rich white dwarfs. As a consequence, a significant fraction of all stars which end their lives as white dwarfs should pass through the helium star phase. (orig.) [de

Investigation of impurity-helium solid phase decomposition

International Nuclear Information System (INIS)

Boltnev, R.E.; Gordon, E.B.; Krushinskaya, I.N.; Martynenko, M.V.; Pel'menev, A.A.; Popov, E.A.; Khmelenko, V.V.; Shestakov, A.F.

1997-01-01

The element composition of the impurity-helium solid phase (IHSP), grown by injecting helium gas jet, involving Ne, Ar, Kr, and Xe atoms and N 2 molecules, into superfluid helium, has been studied. The measured stoichiometric ratios, S = N H e / N I m, are well over the values expected from the model of frozen together monolayer helium clusters. The theoretical possibility for the freezing of two layers helium clusters is justified in the context of the model of IHSP helium subsystem, filled the space between rigid impurity centers. The process of decomposition of impurity-helium (IH)-samples taken out of liquid helium in the temperature range 1,5 - 12 K and the pressure range 10-500 Torr has been studied. It is found that there are two stages of samples decomposition: a slow stage characterized by sample self cooling and a fast one accompanied by heat release. These results suggest, that the IHSP consists of two types of helium - weakly bound and strongly bound helium - that can be assigned to the second and the first coordination helium spheres, respectively, formed around heavy impurity particles. A tendency for enhancement of IHSP thermo stability with increasing the impurity mass is observed. Increase of helium vapor pressure above the sample causes the improvement of IH sample stability. Upon destruction of IH samples, containing nitrogen atoms, a thermoluminescence induced by atom recombination has been detected in the temperature region 3-4,5 K. This suggests that numerous chemical reactions may be realized in solidified helium

Thermal optimization of the helium-cooled power leads for the SSC

International Nuclear Information System (INIS)

Demko, J.A.; Schiesser, W.E.; Carcagno, R.; McAshan, M.; McConeghy, R.

1992-03-01

The optimum thermal design of the power leads for the Superconducting Super Collider (SSC) will minimize the amount of Carnot work (which is a combination of refrigeration and liquefaction work) required. This optimization can be accomplished by the judicious selection of lead length and diameter. Even though an optimum set of dimensions is found, the final design must satisfy other physical constraints such as maximum allowable heat leak and helium vapor mass flow rate. A set of corresponding lengths and diameters has been determined that meets these requirements for the helium vapor-cooled, spiral-fin power lead design of the SSC. Early efforts by McFee and Mallon investigated optimizing power leads for cryogenic applications with no convection cooling. Later designs utilized the boiled-off helium vapor to cool the lead. One notable design for currents up to several thousand amps is presented by Efferson based on a series of recommendations discussed by Deiness. Buyanov presents many theoretical models and design formulate but does not demonstrate an approach to thermally optimizing the design of a vapor-cooled lead. A method for optimizing superconducting magnet current leads is described by Maehata et al. The approach assumes that the helium boil-off caused by heat conduction along with power lead into the low-temperature helium is used to cool the lead. The optimum solution is found when the heat flow at the cold end is minimized.. In this study, a detailed numerical thermal model of a power lead design for the SSC has been developed. It was adapted from the dynamic model developed by Schiesser. This model was used to determine the optimum dimensions that minimize the Carnot refrigeration and liquefaction work due to the leads

Ageing of palladium tritide: mechanical characterization, helium state and modelling

International Nuclear Information System (INIS)

Segard, M.

2010-01-01

Palladium is commonly used for the storage of tritium (the hydrogen radioactive isotope), since it forms a low-equilibrium-pressure and reversible tritide. Tritium decay into helium-3 is responsible for the ageing of the tritide, leading to the apparition of helium-3 bubbles for instance. Both experimental and theoretical aspects of this phenomenon are studied here.Previous works on ageing modelling led to two main models, dealing with:- Helium-3 bubbles nucleation (using a cellular automaton), - Bubbles growth (using continuum mechanics).These models were quite efficient, but their use was limited by the lack of input data and fitting experimental parameters.To get through these limitations, this work has consisted in studying the most relevant experimental data to improve the modelling of the palladium tritide ageing.The first part of this work was focused on the assessment of the mechanical properties of the palladium tritide (yield strength, ultimate strength, mechanical behaviour). They were deduced from the in situ tensile tests performed on palladium hydride and deuteride. In the second part, ageing characterization was undertaken, mainly focusing on: - Bubbles observations in palladium tritide using transmission electron microscopy, - Internal bubble pressure measurements using nuclear magnetic resonance, - Macroscopic swelling measurements using pycno-metry.The present work has led to significant progress in ageing understanding and has brought very valuable improvements to the modelling of such a phenomenon. (author) [fr

Mixture of working fluids in ORC plants with pool boiler evaporator

International Nuclear Information System (INIS)

Rajabloo, Talieh; Iora, Paolo; Invernizzi, Costante

2016-01-01

Highlights: • We assess the feasibility of pool boiler in ORCs operating with mixture working fluids. • We consider hydrocarbon and siloxane mixtures for low and high temperature ORCs. • Plants with pool boiler show comparable performances to once through evaporator. - Abstract: Power generation using Organic Rankine Cycle was studied in this paper in case of both low and high temperature cycles, exploiting respectively a geothermal heat source available at 167 °C, and heat available at 300 °C from the combustion of biomass. In particular we assess the feasibility of employing mixture of working fluids, in the case of replacing the typical once-through (OT) evaporator with the pool boiler (PB) technology, typically adopted for pure fluids. The analysis evidenced that in general the OT evaporator shows a slightly improved cycle performance in comparison to the PB and it results in some cases advantageous with respect to the pure working fluid. For instance in case of low temperature cycle, the best thermodynamic performances are obtained with mixture of i-C_5 and 75% n-C_4 in case of OT evaporator, yielding a recovery efficiency higher than the case with pure i-C_5 (7.7 vs. 7.4%) given the relatively higher values of both the recovery factor and cycle efficiency. Implementation of PB did not affect the plant performance significantly which shows the feasibility of having PB with potentially easier control.

Quantum dissipative dynamics and decoherence of dimers on helium droplets

International Nuclear Information System (INIS)

Schlesinger, Martin

2011-01-01

In this thesis, quantum dynamical simulations are performed in order to describe the vibrational motion of diatomic molecules in a highly quantum environment, so-called helium droplets. We aim to reproduce and explain experimental findings which were obtained from dimers on helium droplets. Nanometer-sized helium droplets contain several thousands of 4 He atoms. They serve as a host for embedded atoms or molecules and provide an ultracold ''refrigerator'' for them. Spectroscopy of molecules in or on these droplets reveals information on both the molecule and the helium environment. The droplets are known to be in the superfluid He II phase. Superfluidity in nanoscale systems is a steadily growing field of research. Spectra obtained from full quantum simulations for the unperturbed dimer show deviations from measurements with dimers on helium droplets. These deviations result from the influence of the helium environment on the dimer dynamics. In this work, a well-established quantum optical master equation is used in order to describe the dimer dynamics effectively. The master equation allows to describe damping fully quantum mechanically. By employing that equation in the quantum dynamical simulation, one can study the role of dissipation and decoherence in dimers on helium droplets. The effective description allows to explain experiments with Rb 2 dimers on helium droplets. Here, we identify vibrational damping and associated decoherence as the main explanation for the experimental results. The relation between decoherence and dissipation in Morse-like systems at zero temperature is studied in more detail. The dissipative model is also used to investigate experiments with K 2 dimers on helium droplets. However, by comparing numerical simulations with experimental data, one finds that further mechanisms are active. Here, a good agreement is obtained through accounting for rapid desorption of dimers. We find that decoherence occurs in the electronic manifold of the

Isotopic alloying to tailor helium production rates in mixed spectrum reactors

International Nuclear Information System (INIS)

Mansur, L.K.; Rowcliffe, A.F.; Grossbeck, M.L.; Stoller, R.E.

1985-01-01

The purposes of this work are to increase the understanding of mechanisms by which helium affects microstructure and properties, to aid in the development of materials for fusion reactors, and to obtain data from fission reactors in regimes of direct interest for fusion reactor applications. Isotopic alloying is examined as a means of manipulating the ratio of helium transmutations to atom displacements in mixed spectrum reactors. The application explored is based on artificially altering the relative abundances of the stable isotopes of nickel to systematically vary the fraction of 58 Ni in nickel bearing alloys. The method of calculating helium production rates is described. Results of example calculations for proposed experiments in the High Flux Isotope Reactor are discussed

Reduction of circulation power for helium-cooled fusion reactor blanket using additive CO{sub 2} gas

Energy Technology Data Exchange (ETDEWEB)

Lee, Yeon-Gun [Department of Nuclear Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Department of Nuclear and Energy Engineering, Jeju National University, 102 Jejudaehakno, Jeju-si 690-756, Jeju (Korea, Republic of); Park, Il-Woong [Department of Nuclear Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Lee, Dong Won [Nuclear Fusion Engineering Development Center, Korea Atomic Energy Research Institute, Daedeokdaero 989 beon-gil, Yuseong-gu, Daejeon 305-353 (Korea, Republic of); Park, Goon-Cherl [Department of Nuclear Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of); Kim, Eung-Soo, E-mail: kes7741@snu.ac.kr [Department of Nuclear Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-744 (Korea, Republic of)

2015-11-15

Helium (He) cooling requires large circulation power to remove high heat from plasma side and nuclear heating by high energy neutron in fusion reactors due to its low density. Based on the recent findings that the heat transfer capability of the light gas can be enhanced by mixing another heavier gas, this study adds CO{sub 2} to a reference helium coolant and evaluates the cooling performance of the binary mixture for various compositions. To assess the cooling performance, computational fluid dynamic (CFD) analyses on the KO HCML (Korea Helium Cooled Molten Lithium) TBM are conducted. As a result, it is revealed that the binary mixing of helium, which has favorable thermophysical properties but the density, with a heavier noble gas or an unreactive gas significantly reduces the required circulation power by an order of magnitude with meeting the thermal design requirements. This is attributed to the fact that the density can be highly increased with small amount of a heavier gas while other gas properties are kept relatively comparable. The optimal CO{sub 2} mole fraction is estimated to be 0.4 and the circulation power, in this case, can be reduced to 13% of that of pure helium. This implies that the thermal efficiency of a He-cooled blanket system can be fairly enhanced by means of the proposed binary mixing.

Determination of helium in beryl minerals

International Nuclear Information System (INIS)

Souza Barcellos, E. de.

1985-08-01

In order to obtain the diffusion coefficients of helium in beryl and phenacite samples at various temperatures, helium leak rates were measured in these minerals at these temperatures. Mass spectrometry (MS) was used to obtain helium leak rates and the gas flow was plotted against time. The gas quantity determined by MS was first obtained at various temperatures until no helium leak rate was detected. After that, these samples were irradiated with fast neutrons to produce helium which was measured again. This procedure was used to estimate the experimental error. The quantity of helium produced by interaction of gamma radiation with beryl minerals was theoretically calculated from the amount of thorium-232 at the neighbourhood of the samples. The quantity of helium produced in the minerals due to uranium and thorium decay was calculated using the amount of these heavy elements, and the results were compared with the amounts determined by MS. The amount of potassium-40 was determined in order to derive the quantity of argonium-40, since some workers found argonium in excess in these minerals. The quantity of helium in the beryl samples (s) was determined in the center and in the surface of the samples in order to obtain informations about the effectiveness of the Be(α, η) He reaction. Beryl and phenacite minerals were choosen in this research since they are opposite each other with respect to the helium contents. Both have beryllium in their compositon but beryl hold a large amount of helium while phenacite, in spite of having about three times more beryllium than beryl, do not hold the gas. (author) [pt

Helium localisation in tritides

International Nuclear Information System (INIS)

Flament, J.L.; Lozes, G.

1982-06-01

Study of titanium and LaNi 5 type alloys tritides lattice parameters evolution revealed that helium created by tritium decay remains in interstitial sites up to a limit material dependant concentration. Beyond this one exceeding helium precipites in voids [fr

Measurement of OH density and air-helium mixture ratio in an atmospheric-pressure helium plasma jet

International Nuclear Information System (INIS)

Yonemori, Seiya; Ono, Ryo; Nakagawa, Yusuke; Oda, Tetsuji

2012-01-01

The absolute density of OH radicals in an atmospheric-pressure helium plasma jet is measured using laser-induced fluorescence (LIF). The plasma jet is generated in room air by applying a pulsed high voltage onto a quartz tube with helium gas flow. The time-averaged OH density is 0.10 ppm near the quartz tube nozzle, decreasing away from the nozzle. OH radicals are produced from water vapour in the helium flow, which is humidified by water adsorbed on the inner surface of the helium line and the quartz tube. When helium is artificially humidified using a water bubbler, the OH density increases with humidity and reaches 2.5 ppm when the water vapour content is 200 ppm. Two-dimensional distribution of air-helium mixture ratio in the plasma jet is also measured using the decay rate of the LIF signal waveform which is determined by the quenching rate of laser-excited OH radicals. (paper)

Free-piston driver performance characterisation using experimental shock speeds through helium

Science.gov (United States)

Gildfind, D. E.; James, C. M.; Morgan, R. G.

2015-03-01

Tuned free-piston driver operation involves configuring the driver to produce a relatively steady blast of driver gas over the critical time scales of the experiment. For the purposes of flow condition development and parametric studies, it is useful to establish some average working values of the driver pressure and temperature for a given driver operating condition. However, in practise, these averaged values need to produce sufficiently accurate estimates of performance. In this study, two tuned driver conditions in the X2 expansion tube have been used to generate shock waves through a helium test gas. The measured shock speeds have then been used to calculate the effective driver gas pressure and temperature after diaphragm rupture. Since the driver gas is typically helium, or a mixture of helium and argon, and the test gas is also helium, ideal gas assumptions can be made without significant loss of accuracy. The technique is applicable to tuned free-piston drivers with a simple area change, as well as those using orifice plates. It is shown that this technique can be quickly used to establish average working driver gas properties which produce very good estimates of actual driven shock speed, across a wide range of operating conditions. The use of orifice plates to control piston dynamics at high driver gas sound speeds is also discussed in the paper, and a simple technique for calculating the restriction required to modify an established safe condition for use with lighter gases, such as pure helium, is presented.

Noble gas, binary mixtures for commercial gas-cooled reactor systems

International Nuclear Information System (INIS)

El-Genk, M. S.; Tournier, J. M.

2007-01-01

Commercial gas cooled reactors employ helium as a coolant and working fluid for the Closed Brayton Cycle (CBC) turbo-machines. Helium has the highest thermal conductivity and lowest dynamic viscosity of all noble gases. This paper compares the relative performance of pure helium to binary mixtures of helium and other noble gases of higher molecular weights. The comparison is for the same molecular flow rate, and same operating temperatures and geometry. Results show that although helium is a good working fluid because of its high heat transfer coefficient and significantly lower pumping requirement, a binary gas mixture of He-Xe with M = 15 gm/mole has a heat transfer coefficient that is ∼7% higher than that of helium and requires only 25% of the number stages of the turbo-machines. The binary mixture, however, requires 3.5 times the pumping requirement with helium. The second best working fluid is He-Kr binary mixture with M = 10 gm/mole. It has 4% higher heat transfer coefficient than He and requires 30% of the number of stages in the turbo-machines, but requires twice the pumping power

Effect of Mixed Working Fluid Composition on Binary Cycle Condenser Heat Transfer Coefficients

Energy Technology Data Exchange (ETDEWEB)

Dan Wendt; Greg Mines

2011-10-01

Effect of Mixed Working Fluid Composition on Binary Cycle Condenser Heat Transfer Coefficients Dan Wendt, Greg Mines Idaho National Laboratory The use of mixed working fluids in binary power plants can provide significant increases in plant performance, provided the heat exchangers are designed to take advantage of these fluids non-isothermal phase changes. In the 1980's testing was conducted at DOE's Heat Cycle Research Facility (HCRF) where mixtures of different compositions were vaporized at supercritical pressures and then condensed. This testing had focused on using the data collected to verify that Heat Transfer Research Incorporated (HTRI) codes were suitable for the design of heat exchangers that could be used with mixtures. The HCRF data includes mixture compositions varying from 0% to 40% isopentane and condenser tube orientations of 15{sup o}, 60{sup o}, and 90{sup o} from horizontal. Testing was performed over a range of working fluid and cooling fluid conditions. Though the condenser used in this testing was water cooled, the working fluid condensation occurred on the tube-side of the heat exchanger. This tube-side condensation is analogous to that in an air-cooled condenser. Tube-side condensing heat transfer coefficient information gleaned from the HCRF testing is used in this study to assess the suitability of air-cooled condenser designs for use with mixtures. Results of an air-cooled binary plant process model performed with Aspen Plus indicate that that the optimal mixture composition (producing the maximum net power for the scenario considered) is within the range of compositions for which data exist. The HCRF data is used to assess the impact of composition, tube orientation, and process parameters on the condensing heat transfer coefficients. The sensitivity of the condensing coefficients to these factors is evaluated and the suitability of air-cooled condenser designs with mixtures is assessed. This paper summarizes the evaluation

Tailored Working Fluids for Enhanced Binary Geothermal Power Plants

Energy Technology Data Exchange (ETDEWEB)

Mahmoud, Ahmad [United Technologies Research Center, East Hartford, CT (United States)

2013-01-29

United Technologies Research Center (UTRC), in collaboration with the Georgia Institute of Technology and the National Institute of Standards and Technology will evaluate and develop fundamental and component level models, conduct experiments and generate data to support the use of mixed or enhanced working fluids for geothermal power generation applications.

Resistivity studies of interstitial helium mobility in niobium

International Nuclear Information System (INIS)

Chen, C.G.; Birnbaum, H.K.; Johnson, A.B. Jr.

1979-01-01

The mobility of interstitial helium in Nb and Nb-O alloys was studied in the temperature range of 10-383 K using resistivity measurements. The helium was introduced by radioactive decay of solute tritium (approximately 1 at%). At T < 100 K the resistivity increased due to conversion of tritium trapped at oxygen interstititals to helium. The formation of helium caused a very significant resistance increase at room temperature and above. The results suggest that helium is mobile at temperatures above 295 K and that the precipitation of large helium bubbles occurs along grain boundaries. The mobile helium species may either be single interstitials or small helium clusters. The activation enthalpy for the diffusion of the mobile helium species was estimated to be about 55 kJ/mol (0.66 eV). (Auth.)

Helium-induced hardening effect in polycrystalline tungsten

Science.gov (United States)

Kong, Fanhang; Qu, Miao; Yan, Sha; Zhang, Ailin; Peng, Shixiang; Xue, Jianming; Wang, Yugang

2017-09-01

In this paper, helium induced hardening effect of tungsten was investigated. 50 keV He2+ ions at fluences vary from 5 × 1015 cm-2 to 5 × 1017 cm-2 were implanted into polycrystalline tungsten at RT to create helium bubble-rich layers near the surface. The microstructure and mechanical properties of the irradiated specimens were studied by TEM and nano-indentor. Helium bubble rich layers are formed in near surface region, and the layers become thicker with the rise of fluences. Helium bubbles in the area of helium concentration peak are found to grow up, while the bubble density is almost unchanged. Obvious hardening effect is induced by helium implantation in tungsten. Micro hardness increases rapidly with the fluence firstly, and more slowly when the fluence is above 5 × 1016 cm-2. The hardening effect of tungsten can be attributed to helium bubbles, which is found to be in agreement with the Bacon-Orowan stress formula. The growing diameter is the major factor rather than helium bubbles density (voids distance) in the process of helium implantation at fluences below 5 × 1017 cm-2.

Low helium flux from the mantle inferred from simulations of oceanic helium isotope data

Science.gov (United States)

Bianchi, Daniele; Sarmiento, Jorge L.; Gnanadesikan, Anand; Key, Robert M.; Schlosser, Peter; Newton, Robert

2010-09-01

The high 3He/ 4He isotopic ratio of oceanic helium relative to the atmosphere has long been recognized as the signature of mantle 3He outgassing from the Earth's interior. The outgassing flux of helium is frequently used to normalize estimates of chemical fluxes of elements from the solid Earth, and provides a strong constraint to models of mantle degassing. Here we use a suite of ocean general circulation models and helium isotope data obtained by the World Ocean Circulation Experiment to constrain the flux of helium from the mantle to the oceans. Our results suggest that the currently accepted flux is overestimated by a factor of 2. We show that a flux of 527 ± 102 mol year - 1 is required for ocean general circulation models that produce distributions of ocean ventilation tracers such as radiocarbon and chlorofluorocarbons that match observations. This new estimate calls for a reevaluation of the degassing fluxes of elements that are currently tied to the helium fluxes, including noble gases and carbon dioxide.

Comparative performance analysis of low-temperature Organic Rankine Cycle (ORC) using pure and zeotropic working fluids

International Nuclear Information System (INIS)

Aghahosseini, S.; Dincer, I.

2013-01-01

In this paper, a comprehensive thermodynamic analysis of the low-grade heat source Organic Rankine Cycle (ORC) is conducted and the cycle performance is analyzed and compared for different pure and zeotropic-mixture working fluids. The comparative performance evaluation of the cycle using a combined energy and exergy analysis is carried out by sensitivity assessment of the cycle certain operating parameters such as efficiency, flow rate, irreversibility, and heat input requirement at various temperatures and pressures. The environmental characteristics of the working fluids such as toxicity, flammability, ODP and GWP are studied and the cycle CO 2 emission is compared with different fuel combustion systems. R123, R245fa, R600a, R134a, R407c, and R404a are considered as the potential working fluids. Results from this analysis provide valuable insight into selection of the most suitable working fluids for power generating application at different operating conditions with a minimal environmental impact. -- Highlights: ► Combined energy and exergy analysis is conducted for Organic Rankine Cycle. ► Comparative assessment is performed for different pure and zeotropic working fluids. ► Exergy and energy efficiency, cycle irreversibility, and required external heat are analyzed. ► Toxicity, flammability, ODP and GWP of considered working fluids are studied. ► Environmental benefits of the renewable/waste heat-based ORC are investigated

Observation of visible emission from the molecular helium ion in the afterglow of a dense helium Z-pinch plasma

International Nuclear Information System (INIS)

Tucker, J.E.; Brake, M.L.; Gilgenbach, R.M.

1986-01-01

The authors present the results of axial and radial time resolved visible emission spectroscopy from the afterglow of a dense helium Z-pinch. These results show that the visible emissions in the pinch afterglow are dominated by line emissions from molecular helium and He II. Axial spectroscopy measurements show the occurrence of several absorption bands which cannot be identified as molecular or atomic helium nor impurities from the discharge chamber materials. The authors believe that these absorption bands are attributable to the molecular helium ion which is present in the discharge. The molecular ion has been observed by others in low pressure and temperature helium discharges directly by means of mass spectrometry and indirectly by the presence of helium atoms in the 2/sup 3/S state, (the He 2/sup 3/S state is believed to result from molecular helium ion recombination). However, the molecular helium ion has not previously been observed spectroscopically

Tensile properties of helium-injected V-15Cr-5Ti after irradiation in EBR-II

International Nuclear Information System (INIS)

Grossbeck, M.L.; Horak, J.A.

1985-01-01

Miniature specimens of V-15Cr-5Ti were prepared in the annealed condition and with 10, 20, and 30% cold work. The annealed specimens were cyclotron injected with helium and irradiated in sodium in EBR-II. The cold-worked specimens were irradiated in EBR-II but not helium injected. The specimens were irradiated at 400, 525, 625, and 700 0 C and received a fluence of 4.1 to 5.5 x 10 26 neutrons/m 2 (E > 0.1 meV). Tensile testing revealed very significant embrittlement as a result of the neutron irradiation but a much smaller change, mostly at 400 0 C, resulting from helium injection. 5 references, 9 figures, 2 tables

Computer program for calculating thermodynamic and transport properties of fluids

Science.gov (United States)

Hendricks, R. C.; Braon, A. K.; Peller, I. C.

1975-01-01

Computer code has been developed to provide thermodynamic and transport properties of liquid argon, carbon dioxide, carbon monoxide, fluorine, helium, methane, neon, nitrogen, oxygen, and parahydrogen. Equation of state and transport coefficients are updated and other fluids added as new material becomes available.

Helium Extraction from LNG End Flash

OpenAIRE

Kim, Donghoi

2014-01-01

Helium is an invaluable element as it is widely used in industry such as cryo-genics and welding due to its unique properties. However, helium shortage is expected in near future because of increasing demand and the anxiety of sup-ply. Consequently, helium production has attracted the attention of industry. The main source of He is natural gas and extracting it from LNG end-flash is considered as the most promising way of producing crude helium. Thus, many process suppliers have proposed proc...

Fault-related CO₂ degassing, geothermics, and fluid flow in southern California basins---Physiochemical evidence and modeling

Energy Technology Data Exchange (ETDEWEB)

Boles, James R. [Univ. of California, Santa Barbara, CA (United States); Garven, Grant [Tufts Univ., Medford, MA (United States)

2015-08-04

Our studies have had an important impact on societal issues. Experimental and field observations show that CO₂ degassing, such as might occur from stored CO₂ reservoir gas, can result in significant stable isotopic disequilibrium. In the offshore South Ellwood field of the Santa Barbara channel, we show how oil production has reduced natural seep rates in the area, thereby reducing greenhouse gases. Permeability is calculated to be ~20-30 millidarcys for km-scale fault-focused fluid flow, using changes in natural gas seepage rates from well production, and poroelastic changes in formation pore-water pressure. In the Los Angeles (LA) basin, our characterization of formation water chemistry, including stable isotopic studies, allows the distinction between deep and shallow formations waters. Our multiphase computational-based modeling of petroleum migration demonstrates the important role of major faults on geological-scale fluid migration in the LA basin, and show how petroleum was dammed up against the Newport-Inglewood fault zone in a “geologically fast” interval of time (less than 0.5 million years). Furthermore, these fluid studies also will allow evaluation of potential cross-formational mixing of formation fluids. Lastly, our new study of helium isotopes in the LA basin shows a significant leakage of mantle helium along the Newport Inglewood fault zone (NIFZ), at flow rates up to 2 cm/yr. Crustal-scale fault permeability (~60 microdarcys) and advective versus conductive heat transport rates have been estimated using the observed helium isotopic data. The NIFZ is an important deep-seated fault that may crosscut a proposed basin decollement fault in this heavily populated area, and appears to allow seepage of helium from the mantle sources about 30 km beneath Los Angeles. The helium study has been widely cited in recent weeks by the news media, both in radio and on numerous web sites.

Fault-Related CO₂ Degassing, Geothermics, and Fluid Flow in Southern California Basins--Physiochemical Evidence and Modeling

Energy Technology Data Exchange (ETDEWEB)

Garven, Grant [Tufts Univ., Medford, MA (United States)

2015-08-11

Our studies have had an important impact on societal issues. Experimental and field observations show that CO₂ degassing, such as might occur from stored CO₂ reservoir gas, can result in significant stable isotopic disequilibrium. In the offshore South Ellwood field of the Santa Barbara channel, we show how oil production has reduced natural seep rates in the area, thereby reducing greenhouse gases. Permeability is calculated to be ~20-30 millidarcys for km-scale fault-focused fluid flow, using changes in natural gas seepage rates from well production, and poroelastic changes in formation pore-water pressure. In the Los Angeles (LA) basin, our characterization of formation water chemistry, including stable isotopic studies, allows the distinction between deep and shallow formations waters. Our multiphase computational-based modeling of petroleum migration demonstrates the important role of major faults on geological-scale fluid migration in the LA basin, and show how petroleum was dammed up against the Newport-Inglewood fault zone in a “geologically fast” interval of time (less than 0.5 million years). Furthermore, these fluid studies also will allow evaluation of potential cross-formational mixing of formation fluids. Lastly, our new study of helium isotopes in the LA basin shows a significant leakage of mantle helium along the Newport Inglewood fault zone (NIFZ), at flow rates up to 2 cm/yr. Crustal-scale fault permeability (~60 microdarcys) and advective versus conductive heat transport rates have been estimated using the observed helium isotopic data. The NIFZ is an important deep-seated fault that may crosscut a proposed basin decollement fault in this heavily populated area, and appears to allow seepage of helium from the mantle sources about 30 km beneath Los Angeles. The helium study has been widely cited in recent weeks by the news media, both in radio and on numerous web sites.

Use of separating nozzles or ultra-centrifuges for obtaining helium from gas mixtures containing helium

International Nuclear Information System (INIS)

Reimann, T.

1987-01-01

To obtain helium from gas mixtures containing helium, particularly from natural gas, it is proposed to match the dimensions of the separation devices for a ratio of the molecular weights to be separated of 4:1 of more, which ensures a higher separation factor and therefore a smaller number of separation stages to be connected in series. The process should make reasonably priced separation of helium possible. (orig./HP) [de

Helium diffusion in nickel at high temperatures

International Nuclear Information System (INIS)

Philipps, V.

1980-09-01

Helium has been implanted at certain temperatures between 800 and 1250 0 C into single and polycrystalline Ni-samples with implantation depths between 15 and 90 μm. Simultaneously the helium reemission from the sample is measured by a mass-spectrometer. It has been shown that the time dependence of the observed reemission rate is governed by volume diffusion of the helium. Measuring this time dependence as a function of temperature the helium diffusion constant has been determined. The He-diffusion is interpreted as a interstitial diffusion hindered by thermal vacancies. Depending on the implantation depth more or less of the implanted helium remains in the sample and forms large helium bubbles. (orig./GSCH)

Neutron-induced helium implantation in GCFR cladding

International Nuclear Information System (INIS)

Yamada, H.; Poeppel, R.B.; Sevy, R.H.

1980-10-01

The neutron-induced implantation of helium atoms on the exterior surfaces of the cladding of a prototypic gas-cooled fast reactor (GCFR) has been investigated analytically. A flux of recoil helium particles as high as 4.2 x 10 10 He/cm 2 .s at the cladding surface has been calculated at the peak power location in the core of a 300-MWe GCFR. The calculated profile of the helium implantation rates indicates that although some helium is implanted as deep as 20 μm, more than 99% of helium particles are implanted in the first 2-μm-deep layer below the cladding surface. Therefore, the implanted helium particles should mainly affect surface properties of the GCFR cladding

Study on specifics of thermophysical properties of supercritical fluids in power engineering applications

International Nuclear Information System (INIS)

Mann, David; Pioro, Igor

2015-01-01

SuperCritical Pressures (SCPs) and SuperCritical Fluids (SFCs) are widely used in many industries worldwide. The largest application of SCPs is in the power industry in advanced coal-fired power plants. It is well-known that moving from subcritical-pressure power plants to SCP power plants increases gross thermal efficiency from 38-42% to about 50-55%. Despite all advances in thermal power-plants design and operation worldwide, they are still considered as not “environmentally friendly” due to significant carbon-dioxide emissions and air pollution as a result of the combustion process. In addition, coal-fired power-plants also produce virtual mountains of slag and ash, and other gas emissions that may contribute to acid rains. Therefore, the demand for clean, non-fossil-based electricity is growing. Due to this, nuclear power is considered as a basis for future electricity generation in the world. One of the major problems with current fleet of Nuclear Power Plants (NPPs) is their relatively low thermal efficiencies, especially, of water-cooled-reactor NPPs (the vast majority of NPPs) (30-36%), compared to those of advanced thermal power plants (55-62%). Based on that, next generation or Generation-IV reactors corresponding to those NPPs should definitely be more efficient. Higher level of thermal efficiencies can be reached only due to higher temperatures and, in some cases, higher pressures inside reactors and, especially, in power cycles of Generation-IV NPPs. Analysis of the six concepts of Generation-IV reactors and NPPs shows that three reactor concepts will use SCFs as reactor coolants (helium and water) and all concepts can be linked to SCFs as working fluids in power cycles (SC helium and /or carbon dioxide in the Brayton gas-turbine cycle, and SC water in the Rankine steam-turbine cycle). Therefore, the exact knowledge of specifics of thermophysical properties of SC helium, water and carbon dioxide is very important for any advances in these new

Quantum statistics and liquid helium 3 - helum 4 mixtures

International Nuclear Information System (INIS)

Cohen, E.G.D.

1979-01-01

The behaviour of liquid helium 3-helium 4 mixtures is considered from the point of view of manifestation of quantum statistics effects in macrophysics. The Boze=Einstein statistics is shown to be of great importance for understanding superfluid helium-4 properties whereas the Fermi-Dirac statistics is of importance for understanding helium-3 properties. Without taking into consideration the interaction between the helium atoms it is impossible to understand the basic properties of liquid helium 33 - helium 4 mixtures at constant pressure. Proposed is a simple model of the liquid helium 3-helium 4 mixture, namely the binary mixture consisting of solid spheres of two types subjecting to the Fermi-Dirac and Bose-Einstein statistics relatively. This model predicts correctly the most surprising peculiarities of phase diagrams of concentration dependence on temperature for helium solutions. In particular, the helium 4 Bose-Einstein statistics is responsible for the phase lamination of helium solutions at low temperatures. It starts in the peculiar critical point. The helium 4 Fermi-Dirac statistics results in incomplete phase lamination close to the absolute zero temperatures, that permits operation of a powerful cooling facility, namely refrigerating machine on helium solution

High Efficiency Regenerative Helium Compressor, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Helium plays several critical rolls in spacecraft propulsion. High pressure helium is commonly used to pressurize propellant fuel tanks. Helium cryocoolers can be...

Helium and carbon isotope systematics of Rungwe geothermal gases and fluids; southern Tanzania

Science.gov (United States)

Barry, P. H.

2009-12-01

P. H. BARRY1*, D. R. HILTON1, T. P. FISCHER2, J. M. DE MOOR2, F. MANGASINI3 C. RAMIREZ4 1 Geosciences Research Division, Scripps Institution of Oceanography, UCSD, La Jolla, California 92093-0244, USA (*Correspondence: pbarry@ucsd.edu) 2 Department of Earth and Planetary Sciences, MSC 03 2040, 1 University of New Mexico, Albuquerque, New Mexico 87131-0001, USA. 3 Department of Mining and Mineral Processing Engineering, University of Dar Es Salaam, PO Box 35131, Dar Es Salaam, Tanzania. 4 Centro de Investigaciones en Ciencias Geologicas, Escuela Centroamericana de Geologia, Universidad de Costa Rica. The East African Rift (EAR) is the largest modern example of continental rifting, extending from the Afar depression in the north to the Rungwe region in southern Tanzania. EAR volcanism is attributed to the presence of one or more mantle plumes [1]. Late Miocene to recent volcanism and geothermal activity mark the Rungwe region [2], with mafic eruptions as recently as 200 years ago. Our aim is to delineate the southern geographical extent of plume influence on the propagating EAR by investigating the He-CO2 characteristics of geothermal fluids in the Rungwe region. We report new helium (He) and carbon (C) isotopes (3He/4He, δ13C) and relative abundance (CO2/3He) characteristics for a suite of 20 geothermal gas and fluid samples from 11 different localities in the Rungwe region. He-isotopes are in good agreement with previous reports [3], and range from ~1 RA to ~7 RA (MORB-like values), indicating admixture between upper mantle He and variable proportions of radiogenic He. C-isotopes ranges from -2.8 to -6.5 ‰ (vs. PDB) with all falling in the MORB range (~4.5 ± 2‰). CO2/3He ratios vary over 5 orders of magnitude from ~3 x 10^9 (MORB-like) to higher values (up to ~3 x 10^13) normally associated with crustal lithologies. Taken together, the He-CO2 data can be explained by 2-component mixing of a deep-seated mantle source with crustal component(s). There are no

Biomolecular ions in superfluid helium nanodroplets

Energy Technology Data Exchange (ETDEWEB)

Gonzalez Florez, Ana Isabel

2016-07-01

The function of a biological molecule is closely related to its structure. As a result, understanding and predicting biomolecular structure has become the focus of an extensive field of research. However, the investigation of molecular structure can be hampered by two main difficulties: the inherent complications that may arise from studying biological molecules in their native environment, and the potential congestion of the experimental results as a consequence of the large number of degrees of freedom present in these molecules. In this work, a new experimental setup has been developed and established in order to overcome the afore mentioned limitations combining structure-sensitive gas-phase methods with superfluid helium droplets. First, biological molecules are ionised and brought into the gas phase, often referred to as a clean-room environment, where the species of interest are isolated from their surroundings and, thus, intermolecular interactions are absent. The mass-to-charge selected biomolecules are then embedded inside clusters of superfluid helium with an equilibrium temperature of ∝0.37 K. As a result, the internal energy of the molecules is lowered, thereby reducing the number of populated quantum states. Finally, the local hydrogen bonding patterns of the molecules are investigated by probing specific vibrational modes using the Fritz Haber Institute's free electron laser as a source of infrared radiation. Although the structure of a wide variety of molecules has been studied making use of the sub-Kelvin environment provided by superfluid helium droplets, the suitability of this method for the investigation of biological molecular ions was still unclear. However, the experimental results presented in this thesis demonstrate the applicability of this experimental approach in order to study the structure of intact, large biomolecular ions and the first vibrational spectrum of the protonated pentapeptide leu-enkephalin embedded in helium

Biomolecular ions in superfluid helium nanodroplets

International Nuclear Information System (INIS)

Gonzalez Florez, Ana Isabel

2016-01-01

The function of a biological molecule is closely related to its structure. As a result, understanding and predicting biomolecular structure has become the focus of an extensive field of research. However, the investigation of molecular structure can be hampered by two main difficulties: the inherent complications that may arise from studying biological molecules in their native environment, and the potential congestion of the experimental results as a consequence of the large number of degrees of freedom present in these molecules. In this work, a new experimental setup has been developed and established in order to overcome the afore mentioned limitations combining structure-sensitive gas-phase methods with superfluid helium droplets. First, biological molecules are ionised and brought into the gas phase, often referred to as a clean-room environment, where the species of interest are isolated from their surroundings and, thus, intermolecular interactions are absent. The mass-to-charge selected biomolecules are then embedded inside clusters of superfluid helium with an equilibrium temperature of ∝0.37 K. As a result, the internal energy of the molecules is lowered, thereby reducing the number of populated quantum states. Finally, the local hydrogen bonding patterns of the molecules are investigated by probing specific vibrational modes using the Fritz Haber Institute's free electron laser as a source of infrared radiation. Although the structure of a wide variety of molecules has been studied making use of the sub-Kelvin environment provided by superfluid helium droplets, the suitability of this method for the investigation of biological molecular ions was still unclear. However, the experimental results presented in this thesis demonstrate the applicability of this experimental approach in order to study the structure of intact, large biomolecular ions and the first vibrational spectrum of the protonated pentapeptide leu-enkephalin embedded in helium

Theoretical study of effect of working fluid on the performance of 77–100 K adsorption cryocooler

International Nuclear Information System (INIS)

Luo, B.J.; Wang, Z.L.; Yan, T.; Hong, G.T.; Li, Y.L.; Liang, J.T.

2015-01-01

Highlights: • Investigate the effects of nitrogen, argon and oxygen on the performance of adsorption cryocooler in the range 77–100 K. • A model of adsorption compressor with a two-stage adsorption compressor is constructed and optimized with genetic algorithm. • Working fluid has larger effects on the adsorption compressor than on the cold stage. • The best selection of working fluid depends on the operating parameters. - Abstract: The aim of this study is to investigate the effects of working fluid (nitrogen, argon and oxygen) on the performance of adsorption cryocooler in the range 77–100 K. A thermodynamic model of adsorption cryocooler with two-stage compressor has been constructed. The model is based on quasi-static conditions without considering the temperature profiles and pressure drops across the compressor. It is then analyzed with an optimization toolbox to determine the optimum operating conditions to obtain the optimum performance of adsorption cryocooler. The Coefficient of Performance (COP) for each working fluid in the range 77–100 K is obtained and compared. It is found that working fluid has larger effects on adsorption compressor than on cold stage, and the optimum selection of working fluid depends on the operating parameters

Seismological measurement of solar helium abundance

International Nuclear Information System (INIS)

Vorontsov, S.V.; Pamyatnykh, A.A.

1991-01-01

The internal structure and evolution of the Sun depends on its chemical composition, particularly the helium abundance. In addition, the helium abundance in the solar envelope is thought to represent the protosolar value, making it a datum of cosmological significance. Spectroscopic measurements of the helium abundance are uncertain, and the most reliable estimates until now have come from the calibration of solar evolutionary models. The frequencies of solar acoustic oscillations are sensitive, however, to the behaviour of the speed of sound in the Sun's helium ionization zone, which allows a helioseismological determination of the helium abundance. Sound-speed inversion of helioseismological data can be used for this purpose, but precise frequency measurements of high-degree oscillation modes are needed. Here we describe a new approach based on an analysis of the phase shift of acoustic waves of intermediate-degree modes. From the accurate intermediate-mode data now available, we obtain a helium mass fraction Y=0.25±0.01 in the solar convection zone, significantly smaller than the value Y=0.27-0.29 predicted by recent solar evolutionary models. The discrepancy indicates either that initial helium abundance was reduced in the envelope by downward diffusion or that the protosolar value was lower than currently accepted. (author)

Review of Membranes for Helium Separation and Purification

Directory of Open Access Journals (Sweden)

Colin A. Scholes

2017-02-01

Full Text Available Membrane gas separation has potential for the recovery and purification of helium, because the majority of membranes have selectivity for helium. This review reports on the current state of the research and patent literature for membranes undertaking helium separation. This includes direct recovery from natural gas, as an ancillary stage in natural gas processing, as well as niche applications where helium recycling has potential. A review of the available polymeric and inorganic membranes for helium separation is provided. Commercial gas separation membranes in comparable gas industries are discussed in terms of their potential in helium separation. Also presented are the various membrane process designs patented for the recovery and purification of helium from various sources, as these demonstrate that it is viable to separate helium through currently available polymeric membranes. This review places a particular focus on those processes where membranes are combined in series with another separation technology, commonly pressure swing adsorption. These combined processes have the most potential for membranes to produce a high purity helium product. The review demonstrates that membrane gas separation is technically feasible for helium recovery and purification, though membranes are currently only applied in niche applications focused on reusing helium rather than separation from natural sources.

Experimental evaluation of a non-azeotropic working fluid for geothermal heat pump system

International Nuclear Information System (INIS)

Zhao, L.

2004-01-01

Geothermal energy resources are found in many countries. A reasonable and efficient utilization of these resources has been a worldwide concern. The application of geothermal heat pump systems (GHPS) can help increase the efficiency of using geothermal energy and reduce the thermal pollution to the earth surface. However, this is only possible with a proper working fluid. In this paper, a non-azeotropic working fluid (R290/R600a/R123) is presented for a GHPS where geothermal water at 40-45 deg. C and heating network water at 70-80 deg. C serve as the low and high temperature heat sources. Experimental results show that the coefficient of performance (COP) of a GHPS using the working fluid is above 3.5 with the condensation temperature above 80 deg. C and the condensation pressure below 18 bar, while the temperature of the geothermal water is reduced from 40-46 deg. C to 31-36 deg. C

Investigation of two and three parameter equations of state for cryogenic fluids

International Nuclear Information System (INIS)

Jenkins, S.L.; Majumdar, A.K.; Hendricks, R.C.

1990-01-01

Two-phase flows are a common occurrence in cryogenic engines and an accurate evaluation of the heat-transfer coefficient in two-phase flow is of significant importance in their analysis and design. The thermodynamic equation of state plays a key role in calculating the heat transfer coefficient which is a function of thermodynamic and thermophysical properties. An investigation has been performed to study the performance of two- and three-parameter equations of state to calculate the compressibility factor of cryogenic fluids along the saturation loci. The two-parameter equations considered here are van der Waals and Redlich-Kwong equations of state. The three-parameter equation represented here is the generalized Benedict-Webb-Rubin (BWR) equation of Lee and Kesler. Results have been compared with the modified BWR equation of Bender and the extended BWR equations of Stewart. Seven cryogenic fluids have been tested; oxygen, hydrogen, helium, nitrogen, argon, neon, and air. The performance of the generalized BWR equation is poor for hydrogen and helium. The van der Waals equation is found to be inaccurate for air near the critical point. For helium, all three equations of state become inaccurate near the critical point. 13 refs

Miniature magnetic fluid seal working in liquid environments

Energy Technology Data Exchange (ETDEWEB)

Mitamura, Yoshinori, E-mail: ymitamura@par.odn.ne.jp [Graduate School of Information Science and Technology, Hokkaido University, Sapporo 060-0814 (Japan); Durst, Christopher A., E-mail: chris@procyrion.com [Procyrion, Inc., Houston, TX 77027 (United States)

2017-06-01

This study was carried out to develop a miniature magnetic fluid (MF) seal working in a liquid environment. The miniature MF seal is intended for use in a catheter blood pump. The requirements for the MF seal included a size of less than Ø4×4.5 mm, shaft diameter of 1 mm, sealing pressure of 200 mmHg, shaft speed of up to 40000 rpm, and life of one month. The miniature MF seal was composed of an NdFeB magnet (Ø4×Ø2×1) sandwiched between two pole pieces (Ø4×Ø1.1×0.5). A shield (Ø4×Ø1.2×1.5) was placed on the pole piece facing the liquid to minimize the influence of pump flow on the MF. The seal was installed on a Ø1 shaft. A seal was formed by injecting MF (Ms: 47.8 kA/m and η: 0.5 Pa·sec) into the gap between the pole pieces and the shaft. Total volume of the MF seal was 44 μL. A sealing pressure of 370 mmHg was obtained at motor speeds of 0-40,000 rpm. The seal remained perfect for 10 days in saline under the condition of a pump flow of 1.5 L/min (The test was terminated in accordance with plans). The seal remained intact after ethylene oxide sterilization during which the seal was exposed to high pressures. In conclusion, the newly developed MF seal will be useful for a catheter pump. - Highlights: • A miniature magnetic fluid seal working in a liquid environment was developed. • The seal can be installed on Ø1 mm shaft and can seal against 370 mmHg at 40000 rpm. • The magnetic fluid seal will be useful for a catheter blood pump.

Separation of compressor oil from helium

International Nuclear Information System (INIS)

Strauss, R.; Perrotta, K.A.

1982-01-01

Compression of helium by an oil-sealed rorary screw compressor entrains as much as 4000 parts per million by weight of liquid and vapor oil impurities in the gas. The reduction below about 0.1 ppm for cryogenic applications is discussed. Oil seperation equipment designed for compressed air must be modified significantly to produce the desired results with helium. The main differences between air and helium filtration are described. A description of the coalescers is given with the continuous coalescing of liquid mist from air or other gas illustrated. Oil vapor in helium is discussed in terms of typical compressor oils, experimental procedure for measuring oil vapor concentration, measured volatile hydrocarbons in the lubricants, and calculated concentration of oil vapor in Helium. Liquid oil contamination in helium gas can be reduced well below 0.1 ppm by a properly designed multiple state coalescing filter system containing graded efficiency filter elements. The oil vapor problem is best attached by efficiently treating the oil to remove most of the colatiles before charging the compressor

Optimization of Helium Vessel Design for ILC Cavities

Energy Technology Data Exchange (ETDEWEB)

Fratangelo, Enrico [Univ. of Pisa (Italy)

2009-01-01

The ILC (International Linear Collider) is a proposed new major particle accelerator. It consists of two 20 km long linear accelerators colliding electrons and positrons at an energy exceeding 500 GeV, Achieving this collision energy while keeping reasonable accelerator dimensions requires the use of high electric field superconducting cavities as the main acceleration element. These cavities are operated at l.3 GHz inside an appropriate container (He vessel) at temperatures as low as 1.4 K using superfluid Helium as the refrigerating medium. The purpose of this thesis, in the context of the ILC R&D activities currently in progress at Fermilab (Fermi National Accelerator Laboratory), is the mechanical study of an ILC superconducting cavity and Helium vessel prototype. The main goals of these studies are the determination of the limiting working conditions of the whole He vessel assembly, the simulation of the manufacturing process of the cavity end-caps and the assessment of the Helium vessel's efficiency. In addition this thesis studies the requirements to certify the compliance with the ASME Code of the whole cavity/vessel assembly. Several Finite Elements Analyses were performed by the candidate himself in order to perform the studies listed above and described in detail in Chapters 4 through 8. ln particular the candidate has developed an improved procedure to obtain more accurate results with lower computational times. These procedures will be accurately described in the following chapters. After an introduction that briefly describes the Fennilab and in particular the Technical Division (where all the activities concerning with this thesis were developed), the first part of this thesis (Chapters 2 and 3) explains some of the main aspects of modem particle accelerators. Moreover it describes the most important particle accelerators working at the moment and the basic features of the ILC project. Chapter 4 describes all the activities that were done to

Nuclear fuel rod helium leak inspection apparatus and method

International Nuclear Information System (INIS)

Ahmed, H.J.

1991-01-01

This patent describes an inspection apparatus for testing nuclear fuel rods for helium leaks. It comprises a test chamber being openable and closable for receiving at least one nuclear fuel rod; means separate from the fuel rod for supplying helium and constantly leaking helium at a predetermined known positive value into the test chamber to constantly provide an atmosphere of helium at the predetermined known positive value in the test chamber; and means for sampling the atmosphere within the chamber and measuring the helium in the atmosphere such that a measured helium value below a preset minimum helium value substantially equal to the predetermined known positive value of the atmosphere of helium being constantly provided in the test chamber indicates a malfunction in the inspection apparatus, above a preset maximum helium value greater than the predetermined known positive in the test chamber indicates the existence of a helium leak from the fuel rod, or between the preset minimum and maximum helium values indicates the absence of a helium leak from the fuel rod

Numerical investigation of potential stratification caused by a cryogenic helium spill inside a tunnel

Science.gov (United States)

Sinclair, Cameron; Malecha, Ziemowit; Jedrusyna, Artur

2018-04-01

The sudden release of cryogenic fluid into an accelerator tunnel can pose a significant health and safety risk. For this reason, it is important to evaluate the consequences of such a spill. Previous publications concentrated on either Oxygen Deficiency Hazard or the evaluation of mathematical models using experimental data. No studies to date have focussed on the influence of cryogen inlet conditions on flow development. In this paper, the stratification behaviour of low-temperature helium released into an air-filled accelerator tunnel is investigated for varying helium inlet diameters. A numerical model was constructed using the OpenFOAM Toolbox of a generalised 3D geometry, with similar hydraulic characteristics to the CERN and SLAC tunnels. This model has been validated against published experimental and numerical data. A dimensionless parameter, based on Bakke number, was then determined for the onset of stratification, taking into account the helium inlet diameter; a dimensionless parameter for the degree of stratification was also employed. The simulated flow behaviour is described in terms of these dimensionless parameters, as well as the temperature and oxygen concentration at various heights throughout the tunnel.

Diagnostics of pre-breakdown light emission in a helium coplanar barrier discharge: the presence of neutral bremsstrahlung

Czech Academy of Sciences Publication Activity Database

Navrátil, Z.; Morávek, T.; Ráhel’, J.; Čech, J.; Lalinský, Ondřej; Trunec, D.

2017-01-01

Roč. 26, č. 5 (2017), s. 1-10, č. článku 055025. ISSN 0963-0252 Institutional support: RVO:68081731 Keywords : dielectric barrier discharge * helium * single photon counting * bremsstrahlung * electric field * backward discharge * surface charge Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 3.302, year: 2016

Helium behaviour in implanted boron carbide

Directory of Open Access Journals (Sweden)

Motte Vianney

2015-01-01

Full Text Available When boron carbide is used as a neutron absorber in nuclear power plants, large quantities of helium are produced. To simulate the gas behaviour, helium implantations were carried out in boron carbide. The samples were then annealed up to 1500 °C in order to observe the influence of temperature and duration of annealing. The determination of the helium diffusion coefficient was carried out using the 3He(d,p4He nuclear reaction (NRA method. From the evolution of the width of implanted 3He helium profiles (fluence 1 × 1015/cm2, 3 MeV corresponding to a maximum helium concentration of about 1020/cm3 as a function of annealing temperatures, an Arrhenius diagram was plotted and an apparent diffusion coefficient was deduced (Ea = 0.52 ± 0.11 eV/atom. The dynamic of helium clusters was observed by transmission electron microscopy (TEM of samples implanted with 1.5 × 1016/cm2, 2.8 to 3 MeV 4He ions, leading to an implanted slab about 1 μm wide with a maximum helium concentration of about 1021/cm3. After annealing at 900 °C and 1100 °C, small (5–20 nm flat oriented bubbles appeared in the grain, then at the grain boundaries. At 1500 °C, due to long-range diffusion, intra-granular bubbles were no longer observed; helium segregates at the grain boundaries, either as bubbles or inducing grain boundaries opening.

A graphical criterion for working fluid selection and thermodynamic system comparison in waste heat recovery

International Nuclear Information System (INIS)

Xi, Huan; Li, Ming-Jia; He, Ya-Ling; Tao, Wen-Quan

2015-01-01

In the present study, we proposed a graphical criterion called CE diagram by achieving the Pareto optimal solutions of the annual cash flow and exergy efficiency. This new graphical criterion enables both working fluid selection and thermodynamic system comparison for waste heat recovery. It's better than the existing criterion based on single objective optimization because it is graphical and intuitionistic in the form of diagram. The features of CE diagram were illustrated by studying 5 examples with different heat-source temperatures (ranging between 100 °C to 260 °C), 26 chlorine-free working fluids and two typical ORC systems including basic organic Rankine cycle(BORC) and recuperative organic Rankine cycle (RORC). It is found that the proposed graphical criterion is feasible and can be applied to any closed loop waste heat recovery thermodynamic systems and working fluids. - Highlights: • A graphical method for ORC system comparison/working fluid selection was proposed. • Multi-objectives genetic algorithm (MOGA) was applied for optimizing ORC systems. • Application cases were performed to demonstrate the usage of the proposed method.

Molecular dynamics simulations of the diffusion and coalescence of helium in tungsten

Energy Technology Data Exchange (ETDEWEB)

Zhou, Y.L. [Key Lab for Radiation Physics and Technology, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064 (China); Department of Physics, Guangxi University, Nanning 530004 (China); Wang, J. [Key Lab for Radiation Physics and Technology, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064 (China); Hou, Q., E-mail: qhou@scu.edu.cn [Key Lab for Radiation Physics and Technology, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064 (China); Deng, A.H. [Department of Physics, Sichuan University, Chengdu 610064 (China)

2014-03-15

Molecular dynamics (MD) simulations are performed on the diffusion and coalescence of helium in tungsten. A new method for determining the effective capture radii (ECRs) and the dissociation energies of helium-related defects is proposed in this work. It is observed that the ECR of an interstitial helium atom trapping helium interstitials (denoted as He–He{sub n}, n = 1–3) decreases with increasing temperature, except for He–He{sub 2} at T < 400 K. The traditional view that the ECR is approximately equal to the lattice constant, which has been widely used in kinetic Monte Carlo (KMC) and rate theory (RT) models, is only valid in some cases. However, the ECR between an interstitial helium atom and a substitutional helium atom (denoted as He–HeV) always approximates the third nearest-neighbor tetrahedral positions of the HeV. The diffusion coefficients D{sub n} for helium clusters are also investigated. He{sub 2} migrates more quickly than a single He atom does at T < 400 K, whereas the diffusion path of He{sub 2} changes at higher temperatures. Another counterintuitive observation is that D{sub 5} > D{sub 3} > D{sub 4} at T < 500 K, which can be attributed to the disordered structure of He{sub 5}. The Arrhenius relation describes the diffusion of He{sub n} well in the temperature range from 300 K to 550 K, whereas the diffusion is not a standard thermally activated process at higher temperatures. Taken together, these results help elucidate the initial stage of helium bubble formation in tungsten as well as the requirements of long-term evolution methods such as KMC or RT models.

Helium storage and control system for the PBMR

International Nuclear Information System (INIS)

Verkerk, E.C.

1997-01-01

The power conversion unit will convert the heat energy in the reactor core to electrical power. The direct-closed cycle recuperated Brayton Cycle employed for this concept consists of a primary helium cycle with helium powered turbo compressors and a power turbine. The helium is actively cooled with water before the compression stages. A recuperator is used to preheat the helium before entering the core. The start of the direct cycle is initiated by a mass flow from the helium inventory and control system via a jet pump. When the PBMR is connected to the grid, changes in power demand can be followed by changing the helium flow and pressure inside the primary loop. Small rapid adjustments can be performed without changing the helium inventory of the primary loop. The stator blade settings on the turbines and compressors are adjustable and it is possible to bypass reactor and turbine. This temporarily reduces the efficiency at which the power conversion unit is operating. Larger or long term adjustments require storage or addition of helium in order to maintain a sufficient level of efficiency in the power conversion unit. The helium will be temporarily stored in high pressure tanks. After a rise in power demand it will be injected back into the system. Some possibilities how to store the helium are presented in this paper. The change of helium inventory will cause transients in the primary helium loop in order to acquire the desired power level. At this stage, it seems that the change of helium inventory does not strongly effect the stability of the power conversion unit. (author)

Lithium concentration dependence of implanted helium retention in lithium silicates

Energy Technology Data Exchange (ETDEWEB)

Szocs, D.E., E-mail: szocsd@rmki.kfki.h [KFKI Research Institute for Particle and Nuclear Physics, H-1525 Budapest, P.O. Box 49 (Hungary); Szilagyi, E.; Bogdan, Cs.; Kotai, E. [KFKI Research Institute for Particle and Nuclear Physics, H-1525 Budapest, P.O. Box 49 (Hungary); Horvath, Z.E. [Research Institute for Technical Physics and Materials Science, H-1525 Budapest, P.O. Box 49 (Hungary)

2010-06-15

Helium ions of 500 keV were implanted with a fluence of 1.4 x 10{sup 17} ion/cm{sup 2} into various lithium silicates to investigate whether a threshold level of helium retention exists in Li-containing silicate ceramics similar to that found in SiO{sub x} in previous work. The composition and phases of the as prepared lithium silicates were determined by proton backscattering spectrometry (p-BS) and X-ray diffraction (XRD) methods with an average error of {+-}10%. Electrostatic charging of the samples was successfully eliminated by wrapping the samples in Al foil. The amounts of the retained helium within the samples were determined by subtracting the non-implanted spectra from the implanted ones. The experimental results show a threshold in helium retention depending on the Li concentration. Under 20 at.% all He is able to escape from the material; at around 30 at.% nearly half of the He, while over 65 at.% all implanted He is retained. With compositions expressed in SiO{sub 2} volume percentages, a trend similar to those reported of SiO{sub x} previously is found.

Influence of working fluids on startup mechanism and thermal performance of a closed loop pulsating heat pipe

International Nuclear Information System (INIS)

Patel, Vipul M.; Gaurav; Mehta, Hemantkumar B.

2017-01-01

Highlights: • Startup mechanism and thermal performance of a CLPHP is reported. • Influence of pure fluids, water-based binary fluids and surfactant solutions are investigated. • Startup heat flux is observed lower for acetone and higher for water compared to all other working fluids. • Thermal resistance is observed to decrease with increase in heat input irrespective of working fluids. • CLPHP is observed to perform better with acetone, water-acetone, water-45 PPM and water-60 PPM surfactant solutions. - Abstract: Development of efficient cooling system is a tricky and challenging task in the field of electronics. Pulsating heat pipe has a great prospect in the upcoming days for an effective cooling solution due to its excellent heat transfer characteristics. Experimental investigations are reported on a Closed Loop Pulsating Heat Pipe (CLPHP). The influence of working fluids on startup mechanism and thermal performance of a CLPHP are carried out on 2 mm, nine turn copper capillary. Total eleven (11) working fluids are prepared and investigated. Deionized (DI) Water (H_2O), ethanol (C_2H_6O), methanol (CH_3OH) and acetone (C_3H_6O) are used as pure fluids. The water-based mixture (1:1) of acetone, methanol and ethanol are used as binary fluids. Sodium Dodecyl Sulphate (SDS, NaC_1_2H_2_5SO_4) is used as a surfactant to prepare the water-based surfactant solutions of 30 PPM, 45 PPM, 60 PPM and 100 PPM. The filling ratio is kept as 50%. The vertical bottom heating position of a CLPHP is considered. Heat input is varied in the range of 10–110 W. Significant influence is observed for water-based binary fluids and surfactant solutions on startup mechanism and thermal performance of a CLPHP compared to DI water used as the pure working fluid.

Multi-Objective Optimization of Organic Rankine Cycle Power Plants Using Pure and Mixed Working Fluids

DEFF Research Database (Denmark)

Andreasen, Jesper Graa; Kærn, Martin Ryhl; Pierobon, Leonardo

2016-01-01

, which is beneficial for cycle performance. On the other hand, larger heat transfer surface areas are typically required for evaporation and condensation when zeotropic mixtures are used as working fluids. In order to assess the feasibility of using zeotropic mixtures, it is, therefore, important......For zeotropic mixtures, the temperature varies during phase change, which is opposed to the isothermal phase change of pure fluids. The use of such mixtures as working fluids in organic Rankine cycle power plants enables a minimization of the mean temperature difference of the heat exchangers...

The multiple ionization of helium induced by partially stripped carbon ions

International Nuclear Information System (INIS)

Cai Xiaohong; Chen Ximeng; Shen Ziyong

1996-01-01

The ratios of the double to single ionization cross sections of helium impacted by partially stripped C q+ ions (q = 1,2,3,4) in energy range of 1.5-7.5 MeV were measured by using the time of flight procedure. The n-body classical trajectory Monte Carlo calculation was carried out to get the Olson-Schlachter scaling. The single and double ionization cross sections of helium were obtained by comparing the cross section ratios of the present work with the Olson-Schlachter scaling

Helium behaviour in aluminium under hydrostatic pressure

International Nuclear Information System (INIS)

Sokurskij, Yu.N.; Tebus, V.N.; Zudilin, V.A.; Tumanova, G.M.

1989-01-01

Effect of hydrostatic compression on equilibrium helium bubbles in low aluminium-lithium alloy irradiated in reactor at 570 K is investigated. Measurements of hydrostatic density and electron-microscopic investigations have shown, that application of up to 2 GPa pressure reduces equilibrium size of helium bubbles and reduces helium swelling. Kinetics and thermodynamics of the process are considered with application of 'rigid sphere' equation which describes helium state in bubbles

Self-assembly of iodine in superfluid helium droplets. Halogen bonds and nanocrystals

Energy Technology Data Exchange (ETDEWEB)

He, Yunteng; Zhang, Jie; Lei, Lei; Kong, Wei [Department of Chemistry, Oregon State University, Corvallis, OR (United States)

2017-03-20

We present evidence of halogen bond in iodine clusters formed in superfluid helium droplets based on results from electron diffraction. Iodine crystals are known to form layered structures with intralayer halogen bonds, with interatomic distances shorter than the sum of the van der Waals radii of the two neighboring atoms. The diffraction profile of dimer dominated clusters embedded in helium droplets reveals an interatomic distance of 3.65 Aa, much closer to the value of 3.5 Aa in iodine crystals than to the van der Waals distance of 4.3 Aa. The profile from larger iodine clusters deviates from a single layer structure; instead, a bi-layer structure qualitatively fits the experimental data. This work highlights the possibility of small halogen bonded iodine clusters, albeit in a perhaps limited environment of superfluid helium droplets. The role of superfluid helium in guiding the trapped molecules into local potential minima awaits further investigation. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

Preliminary Overview of a Helium Cooling System for the Secondary Helium Loop in VHTR-based SI Hydrogen Production Facilities

Energy Technology Data Exchange (ETDEWEB)

Shin, Youngjoon; Cho, Mintaek; Kim, Dahee; Lee, Taehoon; Lee, Kiyoung; Kim, Yongwan [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2014-05-15

Nuclear hydrogen production facilities consist of a very high temperature gas-cooled nuclear reactor (VHTR) system, intermediate heat exchanger (IHX) system, and a sulfur-iodine (SI) thermochemical process. This study focuses on the coupling system between the IHX system and SI thermochemical process. To prevent the propagation of the thermal disturbance owing to the abnormal operation of the SI process components from the IHX system to the VHTR system, a helium cooling system for the secondary helium of the IHX is required. In this paper, the helium cooling system has been studied. The temperature fluctuation of the secondary helium owing to the abnormal operation of the SI process was then calculated based on the proposed coupling system model. Finally, the preliminary conceptual design of the helium cooling system with a steam generator and forced-draft air-cooled heat exchanger to mitigate the thermal disturbance has been carried out. A conceptual flow diagram of a helium cooling system between the IHX and SI thermochemical processes in VHTR-based SI hydrogen production facilities has been proposed. A helium cooling system for the secondary helium of the IHX in this flow diagram prevents the propagation of the thermal disturbance from the IHX system to the VHTR system, owing to the abnormal operation of the SI process components. As a result of a dynamic simulation to anticipate the fluctuations of the secondary helium temperature owing to the abnormal operation of the SI process components with a hydrogen production rate of 60 mol·H{sub 2}/s, it is recommended that the maximum helium cooling capacity to recover the normal operation temperature of 450 .deg. C is 31,933.4 kJ/s. To satisfy this helium cooling capacity, a U-type steam generator, which has a heat transfer area of 12 m{sup 2}, and a forced-draft air-cooled condenser, which has a heat transfer area of 12,388.67 m{sup 2}, are required for the secondary helium cooling system.

Model-based minimization algorithm of a supercritical helium loop consumption subject to operational constraints

Science.gov (United States)

Bonne, F.; Bonnay, P.; Girard, A.; Hoa, C.; Lacroix, B.; Le Coz, Q.; Nicollet, S.; Poncet, J.-M.; Zani, L.

2017-12-01

Supercritical helium loops at 4.2 K are the baseline cooling strategy of tokamaks superconducting magnets (JT-60SA, ITER, DEMO, etc.). This loops work with cryogenic circulators that force a supercritical helium flow through the superconducting magnets in order that the temperature stay below the working range all along their length. This paper shows that a supercritical helium loop associated with a saturated liquid helium bath can satisfy temperature constraints in different ways (playing on bath temperature and on the supercritical flow), but that only one is optimal from an energy point of view (every Watt consumed at 4.2 K consumes at least 220 W of electrical power). To find the optimal operational conditions, an algorithm capable of minimizing an objective function (energy consumption at 5 bar, 5 K) subject to constraints has been written. This algorithm works with a supercritical loop model realized with the Simcryogenics [2] library. This article describes the model used and the results of constrained optimization. It will be possible to see that the changes in operating point on the temperature of the magnet (e.g. in case of a change in the plasma configuration) involves large changes on the cryodistribution optimal operating point. Recommendations will be made to ensure that the energetic consumption is kept as low as possible despite the changing operating point. This work is partially supported by EUROfusion Consortium through the Euratom Research and Training Program 20142018 under Grant 633053.

Nucleation path of helium bubbles in metals during irradiation

International Nuclear Information System (INIS)

Morishita, Kazunori

2008-01-01

Thermodynamical formalization is made for description of the nucleation and growth of helium bubbles in metals during irradiation. The proposed formalization is available or evaluating both microstructural changes in fusion first wall materials where helium is produced by (n, α) nuclear transmutation reactions, and those in fusion divertor materials where helium particles with low energy are directly implanted. Calculated nucleation barrier is significantly reduced by the presence of helium, showing that a helium bubble with an appropriate number of helium atoms depending on bubble size can nucleate without any large nucleation barriers, even at a condition where an empty void has very large nucleation barrier without helium. With the proposed thermodynamical formalization, the nucleation and growth process of helium bubbles in iron during irradiation is simulated by the kinetic Monte-Carlo (KMC) technique. It shows the nucleation path of a helium bubble on the (N He , N V ) space as functions of temperatures and the concentration of helium in the matrix, where N He and N V are the number of helium atoms and vacancies in the helium bubble, respectively. Bubble growth rates depend on the nucleation path and suggest that two different mechanisms operate for bubble growth: one is controlled by vacancy diffusion and the other is controlled by interstitial helium diffusion. (author)

Submersible fans and pumps for cryogenic fluids

International Nuclear Information System (INIS)

Mark, J.W.

1986-01-01

Submersible electric motor driven fans of three sizes have been designed, built and operated at 21 0 K at the Stanford Linear Accelerator Center. The largest is a 100-mm diameter, 2 stage vaneaxial fan with a nominal capacity of 6 L/s at 2 m head. It is driven by a 4 pole, 3 phase induction motor that runs at 1750 rpm. The next smaller one is an 85-mm diameter centrifugal pump. It pumps 3 L/s at a head of 5 m. The third is a 75-mm single stage vaneaxial fan with a nominal capacity is 3 L/s at a head of 2 m. The 85-mm pump and the 75-mm fan are driven by 2 pole, 3 phase induction motors running at 3550 rpm. The motors were modified to operate submerged in the cryogenic fluid. The pumps have been operated in liquid hydrogen, liquid deuterium, and pressurized helium gas at 21 0 K. They can also operate with denser fluids such as liquid nitrogen, but rotational speed, capacity, and head will be reduced. They have been operated while submerged in liquid helium

A High Reliability Gas-driven Helium Cryogenic Centrifugal Compressor

CERN Document Server

Bonneton, M; Gistau-Baguer, Guy M; Turcat, F; Viennot, P

1998-01-01

A helium cryogenic compressor was developed and tested in real conditions in 1996. The achieved objective was to compress 0.018 kg/s Helium at 4 K @ 1000 Pa (10 mbar) up to 3000 Pa (30 mbar). This project was an opportunity to develop and test an interesting new concept in view of future needs. The main features of this new specific technology are described. Particular attention is paid to the gas bearing supported rotor and to the pneumatic driver. Trade off between existing technologies and the present work are presented with special stress on the bearing system and the driver. The advantages are discussed, essentially focused on life time and high reliability without maintenance as well as non pollution characteristic. Practical operational modes are also described together with the experimental performances of the compressor. The article concludes with a brief outlook of future work.

Numerical research on the neutronic/thermal-hydraulic/mechanical coupling characteristics of the optimized helium cooled solid breeder blanket for CFETR

International Nuclear Information System (INIS)

Cui, Shijie; Zhang, Dalin; Cheng, Jie; Tian, Wenxi; Su, G.H.

2017-01-01

As one of the candidate tritium breeding blankets for Chinese Fusion Engineering Test Reactor (CFETR), a conceptual structure of the helium cooled solid breeder blanket has recently been proposed. The neutronic, thermal-hydraulic and mechanical characteristics of the blanket directly affect its tritium breeding and safety performance. Therefore, neutronic/thermal-hydraulic/mechanical coupling analyses are of vital importance for a reliable blanket design. In this work, first, three-dimensional neutronics analysis and optimization of the typical outboard equatorial blanket module (No. 12) were performed for the comprehensive optimal scheme. Then, thermal and fluid dynamic analyses of the scheme under both normal and critical conditions were performed and coupled with the previous neutronic calculation results. With thermal-hydraulic boundaries, thermo-mechanical analyses of the structure materials under normal, critical and blanket over-pressurization conditions were carried out. In addition, several parametric sensitivity studies were also conducted to investigate the influences of the main parameters on the blanket temperature distributions. In this paper, the coupled analyses verify the reasonability of the optimized conceptual design preliminarily and can provide an important reference for the further analysis and optimization design of the CFETR helium cooled solid breeder blanket.

Numerical research on the neutronic/thermal-hydraulic/mechanical coupling characteristics of the optimized helium cooled solid breeder blanket for CFETR

Energy Technology Data Exchange (ETDEWEB)

Cui, Shijie; Zhang, Dalin, E-mail: dlzhang@mail.xjtu.edu.cn; Cheng, Jie; Tian, Wenxi; Su, G.H.

2017-01-15

As one of the candidate tritium breeding blankets for Chinese Fusion Engineering Test Reactor (CFETR), a conceptual structure of the helium cooled solid breeder blanket has recently been proposed. The neutronic, thermal-hydraulic and mechanical characteristics of the blanket directly affect its tritium breeding and safety performance. Therefore, neutronic/thermal-hydraulic/mechanical coupling analyses are of vital importance for a reliable blanket design. In this work, first, three-dimensional neutronics analysis and optimization of the typical outboard equatorial blanket module (No. 12) were performed for the comprehensive optimal scheme. Then, thermal and fluid dynamic analyses of the scheme under both normal and critical conditions were performed and coupled with the previous neutronic calculation results. With thermal-hydraulic boundaries, thermo-mechanical analyses of the structure materials under normal, critical and blanket over-pressurization conditions were carried out. In addition, several parametric sensitivity studies were also conducted to investigate the influences of the main parameters on the blanket temperature distributions. In this paper, the coupled analyses verify the reasonability of the optimized conceptual design preliminarily and can provide an important reference for the further analysis and optimization design of the CFETR helium cooled solid breeder blanket.

High-temperature helium-loop facility

International Nuclear Information System (INIS)

Tokarz, R.D.

1981-09-01

The high-temperature helium loop is a facility for materials testing in ultrapure helium gas at high temperatures. The closed loop system is capable of recirculating high-purity helium or helium with controlled impurities. The gas loop maximum operating conditions are as follows: 300 psi pressure, 500 lb/h flow rate, and 2100 0 F temperature. The two test sections can accept samples up to 3.5 in. diameter and 5 ft long. The gas loop is fully instrumented to continuously monitor all parameters of loop operation as well as helium impurities. The loop is fully automated to operate continuously and requires only a daily servicing by a qualified operator to replenish recorder charts and helium makeup gas. Because of its versatility and high degree of parameter control, the helium loop is applicable to many types of materials research. This report describes the test apparatus, operating parameters, peripheral systems, and instrumentation system. The experimental capabilities and test conand presents the results that have been obtained. The study has been conducted using a four-phase approach. The first phase develops the solution to the steady-state radon-diffusion equation in one-dimensieered barriers; disposal charge analysis; analysis of spent fuel policy implementation; spent f water. Field measurements and observations are reported for each site. Analytical data and field measurements are presented in tables and maps. Uranium concentrations in the sediments which were above detection limits ranged from 0.10 t 51.2 ppM. The mean of the logarithms of the uranium concentrations was 0.53. A group of high uranium concentrations occurs near the junctions of quadrangles AB, AC, BB, a 200 mK. In case 2), x-ray studies of isotopic phase separation in 3 He-- 4 He bcc solids were carried out by B. A. Fraass

Molecular dynamics study of the role of symmetric tilt grain boundaries on the helium distribution in nickel

Science.gov (United States)

Torres, E.; Pencer, J.

2018-04-01

Helium impurities, from either direct implantation or transmutation reactions, have been associated with embrittlement in nickel-based alloys. Helium has very low solubility in nickel, and has been found to aggregate at lattice defects such as vacancies, dislocations, and grain boundaries. The retention and precipitation of helium in nickel-based alloys have deleterious effects on the material mechanical properties. However, the underlying mechanisms that lead to helium effects in the host metal are not fully understood. In the present work, we investigate the role of symmetric tilt grain boundary (STGB) structures on the distribution of helium in nickel using molecular dynamics simulations. We investigate the family of STGBs specific to the 〈 110 〉 tilt axis. The present results indicate that accumulation of helium at the grain boundary may be modulated by details of grain boundary geometry. A plausible correlation between the grain boundary energy and misorientation with the accumulation and mobility of helium is proposed. Small clusters with up to 6 helium atoms show significant interstitial mobility in the nickel bulk, but also become sites for nucleation and grow of more stable helium clusters. High-energy GBs are found mainly populated with small helium clusters. The high mobility of small clusters along the GBs indicates the role of these GBs as fast two-dimensional channels for diffusion. In contrast, the accumulation of helium in large helium clusters at low-energy STGB creates a favorable environment for the formation of large helium bubbles, indicating a potential role for low-energy STGB in promoting helium-induced GB embrittlement.

Effect of helium on void swelling in vanadium

International Nuclear Information System (INIS)

Brimhall, J.L.; Simonen, E.P.

1975-01-01

Little difference in void microstructural swelling of vanadium is observed when helium is injected simultaneously with a 46- or 5-MeV nickel beam as compared to no helium injection, at least at high dose rates. At lower dose rates, a strong helium effect is seen when the helium is injected prior to heavy ion bombardment. The effect of the helium is shown to be a strong function of the overall displacement damage rate

Multiphase numerical analysis of heat pipe with different working fluids for solar applications

Science.gov (United States)

Aswath, S.; Netaji Naidu, V. H.; Padmanathan, P.; Raja Sekhar, Y.

2017-11-01

Energy crisis is a prognosis predicted in many cases with the indiscriminate encroachment of conventional energy sources for applications on a massive scale. This prediction, further emboldened by the marked surge in global average temperatures, attributed to climate change and global warming, the necessity to conserve the environment and explore alternate sources of energy is at an all-time high. Despite being among the lead candidates for such sources, solar energy is utilized far from its vast potential possibilities due to predominant economic constraints. Even while there is a growing need for solar panels at more affordable rates, the other options to harness better out of sun’s energy is to optimize and improvise existing technology. One such technology is the heat pipe used in Evacuated Tube Collectors (ETC). The applications of heat pipe have been gaining momentum in various fields since its inception and substantial volumes of research have explored optimizing and improving the technology which is proving effective in heat recovery and heat transfer better than conventional systems. This paper carries out a computational analysis on a comparative simulation between two working fluids within heat pipe of same geometry. It further endeavors to study the multiphase transitions within the heat pipe. The work is carried out using ANSYS Fluent with inputs taken from solar data for the location of Vellore, Tamil Nadu. A wickless, gravity-assisted heat pipe (GAHP) is taken for the simulation. Water and ammonia are used as the working fluids for comparative multiphase analysis to arrive at the difference in heat transfer at the condenser section. It is demonstrated that a heat pipe ETC with ammonia as working fluid showed higher heat exchange (temperature difference) as against that of water as working fluid. The multiphase model taken aided in study of phase transitions within both cases and supported the result of ammonia as fluid being a better candidate.

Clustering of Helium Atoms at a ½

NARCIS (Netherlands)

Berg, F. v.d.; Heugten, W. v.; Caspers, L.M.; Veen, A. v.; Hosson, J.Th.M. de

1977-01-01

Atomistic calculations on a ½<111>{110} edge dislocation show a restricted tendency of clustering of helium atom along this dislocation. Clusters with up to 4 helium atoms have been studied. A cluster with 3 helium proved to be most stable.

Effects of helium content of microstructural development in Type 316 stainless steel under neutron irradiation

International Nuclear Information System (INIS)

Maziasz, P.J.

1985-11-01

This work investigated the sensitivity of microstructural evolution, particularly precipitate development, to increased helium content during thermal aging and during neutron irradiation. Helium (110 at. ppM) was cold preinjected into solution annealed (SA) DO-heat type 316 stainess steel (316) via cyclotron irradiation. These specimens were then exposed side by side with uninjected samples. Continuous helium generation was increased considerably relative to EBR-II irradiation by irradiation in HFIR. Data were obtained from quantitative analytical electron microscopy (AEM) in thin foils and on extraction replicas. 480 refs., 86 figs., 19 tabs

Effects of helium content of microstructural development in Type 316 stainless steel under neutron irradiation

Energy Technology Data Exchange (ETDEWEB)

Maziasz, P.J.

1985-11-01

This work investigated the sensitivity of microstructural evolution, particularly precipitate development, to increased helium content during thermal aging and during neutron irradiation. Helium (110 at. ppM) was cold preinjected into solution annealed (SA) DO-heat type 316 stainess steel (316) via cyclotron irradiation. These specimens were then exposed side by side with uninjected samples. Continuous helium generation was increased considerably relative to EBR-II irradiation by irradiation in HFIR. Data were obtained from quantitative analytical electron microscopy (AEM) in thin foils and on extraction replicas. 480 refs., 86 figs., 19 tabs.

Effect of helium on void formation in nickel

International Nuclear Information System (INIS)

Brimhall, J.L.; Simonen, E.P.

1977-01-01

This study examines the influence of helium on void formation in self-ion irradiated nickel. Helium was injected either simultaneously with, or prior to, the self-ion bombardment. The void microstructure was characterized as a function of helium deposition rate and the total heavy-ion dose. In particular, at 575 0 C and 5 X 10 -3 displacements per atom per second the void density is found to be proportional to the helium deposition rate. The dose dependence of swelling is initially dominated by helium driven nucleation. The void density rapidly saturates after which swelling continues with increasing dose only from void growth. It is concluded that helium promotes void nucleation in nickel with either helium implantation technique, pre-injection or simultaneous injection. Qualitative differences, however, are recognized. (Auth.)

The installation of helium auxiliary systems in HTGR

International Nuclear Information System (INIS)

Qin Zhenya; Fu Xiaodong

1993-01-01

The inert gas Helium was chosen as reactor coolant in high temperature gas coolant reactor, therefore a set of Special and uncomplex helium auxiliary systems will be installed, the safe operation of HTR-10 can be safeguarded. It does not effect the inherent safety of HTR-10 MW if any one of all those systems were damaged during operation condition. This article introduces the design function and the system principle of all helium auxiliary systems to be installed in HTR-10. Those systems include: helium purification and its regeneration system, helium supply and storage system, pressure control and release system of primary system, dump system for helium auxiliary system and fuel handling, gaseous waste storage system, water extraction system for helium auxiliary systems and evacuation system for primary system

Some research and development on power plants with helium gas turbine units

International Nuclear Information System (INIS)

Kaplan, M.P.

1983-01-01

Research and development projects pursued at the S. M. Kirov Kharkov Turbine Factory Production Association for Nuclear Turbomachinery Manufacturing have probed into prospective use of helium as the working medium in nuclear power facilities. The projects under study are compared mainly in terms of heat efficiency. Solutions are also being sought for problems centering around high efficiency in helium turbocompressors combined with shortening of axial dimensions. Different types of power plants are being compared with attention given to features of the flow passages of turbocompressors. The projects were developed for helium temperatures and pressures downstream of the reactor 950 0 C and 4.8 MPa, and thermal reactor output 2250 MW(th). The reactor is assumed to be served by two turbine plants in the turbocompressor designs

'In-beam' simulation of high temperature helium embrittlement of DIN 1.4970 austenitic stainless steel

International Nuclear Information System (INIS)

Schroeder, H.; Batfalsky, P.

1982-01-01

This work describes a facility for high temperature creep rupture tests during homogeneous helium implantation. This 'in-beam' creep testing facility is used to simulate helium embrittlement effects which will be very important for first wall materials of future fusion reactors operated at high temperatures. First results for DIN 1.4970 austenitic stainless steel clearly demonstrate differences between samples 'in-beam' tested at 1073 K and those creep tested at the same temperature after room temperature helium implantation. The specimens ruptured 'in-beam' have much shorter lifetimes and lower ductility than the specimens tested after room temperature implantation. There are also differences in the microstructures, concerning helium bubble sizes and densities in matrix and grain boundaries. These microstructural differences may be a key for the understanding of the more severe helium embrittlement effects 'in-beam' as compared to creep tests performed after room temperature implantation. (orig.)

Heat transfer in cryogenic helium gas by turbulent Rayleigh-Bénard convection in a cylindrical cell of aspect ratio 1

Czech Academy of Sciences Publication Activity Database

Urban, Pavel; Hanzelka, Pavel; Musilová, Věra; Králík, Tomáš; La Mantia, M.; Srnka, Aleš; Skrbek, L.

2014-01-01

Roč. 16, č. 5 (2014), 053042: 1-40 ISSN 1367-2630 R&D Projects: GA ČR GPP203/12/P897 Institutional support: RVO:68081731 Keywords : Rayleigh-Bénard convection * heat transfer efficiency * cryogenic helium Subject RIV: BK - Fluid Dynamics Impact factor: 3.558, year: 2014

Performance Study of Solar Heat Pipe with Different Working Fluids and Fill Ratios

Science.gov (United States)

Harikrishnan, S. S.; Kotebavi, Vinod

2016-09-01

This paper elaborates on the testing of solar heat pipes using different working fluids, fill ratios and tilt angles. Methanol, Acetone and water are used as working fluids, with fill ratios 25%, 50%, 75% and 100%. Experiments were carried out at 600 and 350 inclinations. Heat pipe condenser section is placed inside a water basin containing 200ml of water. The evaporator section is exposed to sunlight where the working fluid gets heated and it becomes vapour and moves towards the condenser section. In the condenser section the heat is given to the water in the basin and the vapour becomes liquid and comes back to the evaporator section due to gravitational force. Two modes of experiments are carried out: 1) using a parabolic collector and 2) using heat pipe with evacuated tubes. On comparative study, optimum fill ratio is been found to be 25% in every case and acetone exhibited slightly more efficiency than methanol and water. As far as the heat pipe orientation is concerned, 600 inclination of the heat pipe showed better performance than 350

Mass spectrometric analysis of helium in stainless steel

International Nuclear Information System (INIS)

Isagawa, Hiroto; Wada, Yukio; Asakura, Yoshiro; Tsuji, Nobuo; Sato, Hitoshi; Tsutsumi, Kenichi

1974-01-01

Vacuum fusion mass-spectrometry was adopted for the analysis of helium in stainless steel. Samples were heated in a vacuum crucible, and helium in the samples was extracted and collected into a reservoir tank. The gas was then introduced through an orifice into a mass spectrometer, where the amount of helium was determined. The maspeq 070 quadrupole type mass spectrometer made by Shimazu Seisakusho, Ltd. was used. The resolving power was 150, and the mass range of the apparatus was 0-150. The determination limit of helium was about 2 x 10 -3 μg when standard helium gas was analyzed, and was about 10 -2 μg when the helium in stainless steel was analyzed. The relative standard deviation of helium intensity in repetitive measurement was about 2% in the amount of helium of 0.05 μg. Helium was injected into stainless steel by means of alpha particle irradiation with a cyclotron. The amount of helium in stainless steel was then determined. The energy of alpha particles was 34 MeV, and the beam area was 10 mm x 10 mm. The experimental data were higher than the expected value in one case, and were lower in the other case. This difference was attributable to the fluctuation of alpha particle beam, misplacement of sample plates, and unevenness of the alpha beam. (Fukutomi, T.)

Comparative investigation of working fluids for an organic Rankine cycle with geothermal water

Directory of Open Access Journals (Sweden)

Liu Yan-Na

2015-06-01

Full Text Available In this paper, the thermodynamic investigation on the use of geothermal water (130 °C as maximum for power generation through a basic Rankine has been presented together with obtained main results. Six typical organic working fluids (i.e., R245fa, R141b, R290, R600, R152a, and 134a were studied with modifying the input pressure and temperature to the turbine. The results show that there are no significant changes taking place in the efficiency for these working fluids with overheating the inlet fluid to the turbine, i.e., efficiency is a weak function of temperature. However, with the increasing of pressure ratio in the turbine, the efficiency rises more sharply. The technical viability is shown of implementing this type of process for recovering low temperature heat resource.

Helium trapping in aluminum and sintered aluminum powders

International Nuclear Information System (INIS)

Das, S.K.; Kaminsky, M.; Rossing, T.

1975-01-01

The surface erosion of annealed aluminum and of sintered aluminum powder (SAP) due to blistering from implantation of 100-keV 4 He + ions at room temperature has been investigated. A substantial reduction in the blistering erosion rate in SAP was observed from that in pure annealed aluminum. In order to determine whether the observed reduction in blistering is due to enhanced helium trapping or due to helium released, the implanted helium profiles in annealed aluminum and in SAP have been studied by Rutherford backscattering. The results show that more helium is trapped in SAP than in aluminum for identical irradiation conditions. The observed reduction in erosion from helium blistering in SAP is more likely due to the dispersion of trapped helium at the large Al-Al 2 O 3 interfaces and at the large grain boundaries in SAP than to helium release

Helium cooling of fusion reactors

International Nuclear Information System (INIS)

Wong, C.P.C.; Baxi, C.; Bourque, R.; Dahms, C.; Inamati, S.; Ryder, R.; Sager, G.; Schleicher, R.

1994-01-01

On the basis of worldwide design experience and in coordination with the evolution of the International Thermonuclear Experimental Reactor (ITER) program, the application of helium as a coolant for fusion appears to be at the verge of a transition from conceptual design to engineering development. This paper presents a review of the use of helium as the coolant for fusion reactor blanket and divertor designs. The concept of a high-pressure helium cooling radial plate design was studied for both ITER and PULSAR. These designs can resolve many engineering issues, and can help with reaching the goals of low activation and high performance designs. The combination of helium cooling, advanced low-activation materials, and gas turbine technology may permit high thermal efficiency and reduced costs, resulting in the environmental advantages and competitive economics required to make fusion a 21st century power source. ((orig.))

Preliminary study on helium turbomachine for high temperature gas-cooled reactor

International Nuclear Information System (INIS)

Chen Yihua; Wang Jie; Zhang Zuoyi

2003-01-01

In the high temperature gas-cooled reactor (HTGR), gas turbine cycle is a new concept in the field of nuclear power. It combines two technologies of HTGR and gas turbine cycle, which represent the state-of-the-art technologies of nuclear power and fossil fuel generation respectively. This approach is expected to improve safety and economy of nuclear power plant significantly. So it is a potential scheme with competitiveness. The heat-recuperated cycle is the main stream of gas turbine cycle. In this cycle, the work medium is helium, which is very different from the air, so that the design features of the helium turbomachine and combustion gas turbomachine are different. The paper shows the basic design consideration for the heat-recuperated cycle as well as helium turbomachine and highlights its main design features compared with combustion gas turbomachine

Dust as a Working Fluid for Heat Transfer Project

Science.gov (United States)

Mantovani, James G.

2015-01-01

The project known as "Dust as a Working Fluid" demonstrates the feasibility of a dust-based system for transferring heat radiatively into space for those space applications requiring higher efficiency, lower mass, and the need to operate in extreme vacuum and thermal environments - including operating in low or zero gravity conditions in which the dust can be conveyed much more easily than on Earth.

Power cycles with ammonia-water mixtures as working fluid

Energy Technology Data Exchange (ETDEWEB)

Thorin, Eva

2000-05-01

It is of great interest to improve the efficiency of power generating processes, i.e. to convert more of the energy in the heat source to power. This is favorable from an environmental point of view and can also be an economic advantage. To use an ammonia-water mixture instead of water as working fluid is a possible way to improve the efficiency of steam turbine processes. This thesis includes studies of power cycles with ammonia-water mixtures as working fluid utilizing different kinds of heat sources for power and heat generation. The thermophysical properties of the mixture are also studied. They play an important role in the calculations of the process performance and for the design of its components, such as heat exchangers. The studies concern thermodynamic simulations of processes in applications suitable for Swedish conditions. Available correlations for the thermophysical properties are compared and their influence on simulations and heat exchanger area predictions is investigated. Measurements of ammonia-water mixture viscosities using a vibrating wire viscometer are also described. The studies performed show that power cycles with ammonia-water mixtures as the working fluid are well suited for utilization of waste heat from industry and from gas engines. The ammonia-water power cycles can give up to 32 % more power in the industrial waste heat application and up to 54 % more power in the gas engine bottoming cycle application compared to a conventional Rankine steam cycle. However, ammonia-water power cycles in small direct-fired biomass-fueled cogeneration plants do not show better performance than a conventional Rankine steam cycle. When different correlations for the thermodynamic properties are used in simulations of a simple ammonia-water power cycle the difference in efficiency is not larger than 4 %, corresponding to about 1.3 percentage points. The differences in saturation properties between the correlations are, however, considerable at high

Investigation of Countercurrent Helium-Air Flows in Air-ingress Accidents for VHTRs

Energy Technology Data Exchange (ETDEWEB)

Sun, Xiaodong; Christensen, Richard; Oh, Chang

2013-10-03

The primary objective of this research is to develop an extensive experimental database for the air- ingress phenomenon for the validation of computational fluid dynamics (CFD) analyses. This research is intended to be a separate-effects experimental study. However, the project team will perform a careful scaling analysis prior to designing a scaled-down test facility in order to closely tie this research with the real application. As a reference design in this study, the team will use the 600 MWth gas turbine modular helium reactor (GT-MHR) developed by General Atomic. In the test matrix of the experiments, researchers will vary the temperature and pressure of the helium— along with break size, location, shape, and orientation—to simulate deferent scenarios and to identify potential mitigation strategies. Under support of the Department of Energy, a high-temperature helium test facility has been designed and is currently being constructed at Ohio State University, primarily for high- temperature compact heat exchanger testing for the VHTR program. Once the facility is in operation (expected April 2009), this study will utilize high-temperature helium up to 900°C and 3 MPa for loss-of-coolant accident (LOCA) depressurization and air-ingress experiments. The project team will first conduct a scaling study and then design an air-ingress test facility. The major parameter to be measured in the experiments is oxygen (or nitrogen) concentration history at various locations following a LOCA scenario. The team will use two measurement techniques: 1) oxygen (or similar type) sensors employed in the flow field, which will introduce some undesirable intrusiveness, disturbing the flow, and 2) a planar laser-induced fluorescence (PLIF) imaging technique, which has no physical intrusiveness to the flow but requires a transparent window or test section that the laser beam can penetrate. The team will construct two test facilities, one for high-temperature helium tests with

Microstructural observation on helium injected and creep ruptured JPCA

International Nuclear Information System (INIS)

Yamamoto, N.; Shiraishi, H.; Hishinuma, A.

1986-01-01

Detailed and quantitative TEM observation was performed on high temperature helium injected and creep ruptured JPCA to seek the prominent TiC distribution developed for suppression of helium embrittlement. Three different preinjection treatments were adopted for changing the TiC distribution. Considerable degradation in creep rupture strength by helium occurred in solution-annealed specimens, although there was much less effect of other treatments which included aging prior to injection. The concentration of helium at grain boundaries and the promotion of precipitation by helium during injection were responsible for the degradation. Therefore, the presence of TiC precipitates before helium introduction will help prevent degradation. On the other hand, the rupture elongation was reduced by helium after all treatments, although helium trapping by TiC precipitates in the matrix was successfully achieved. Consequently, the combined use of several methods may be necessary for further suppression of helium embrittlement. (orig.)

Dependence of cycle optimal configuration for closed gas turbines on thermodynamic properties of working fluids

International Nuclear Information System (INIS)

Andryushchenko, A.I.; Dubinin, A.B.; Krylov, E.E.

1988-01-01

The problem of choice of working fluids for NPP closed gas turbines (CGT) is discussed. Thermostable in the working temperature range, chemically inert relatively to structural materials, fire- and explosion - proof substances, radiation-resistant and having satisfactory neutron-physical characteristics are used as the working fluids. Final choice of a gas as a working fluid is exercised based on technical and economic comparison of different variants at optimum thermodynamic cycle and parameters for each gas. The character and degree of the effect of thermodynamic properties of gases on configuration of reference cycles of regenerative CGT are determined. It is established that efficiency and optimum parameters in nodal points of the reference cycle are specified by the degree of removing the compression processes from the critical point. Practical importance of the obtained results presupposes the possibility of rapid estimation of the efficiency of using a gas without multiparametric optimization

Helium induced fine structure in the electronic spectra of anthracene derivatives doped into superfluid helium nanodroplets

International Nuclear Information System (INIS)

Pentlehner, D.; Slenczka, A.

2015-01-01

Electronic spectra of organic molecules doped into superfluid helium nanodroplets show characteristic features induced by the helium environment. Besides a solvent induced shift of the electronic transition frequency, in many cases, a spectral fine structure can be resolved for electronic and vibronic transitions which goes beyond the expected feature of a zero phonon line accompanied by a phonon wing as known from matrix isolation spectroscopy. The spectral shape of the zero phonon line and the helium induced phonon wing depends strongly on the dopant species. Phonon wings, for example, are reported ranging from single or multiple sharp transitions to broad (Δν > 100 cm −1 ) diffuse signals. Despite the large number of example spectra in the literature, a quantitative understanding of the helium induced fine structure of the zero phonon line and the phonon wing is missing. Our approach is a systematic investigation of related molecular compounds, which may help to shed light on this key feature of microsolvation in superfluid helium droplets. This paper is part of a comparative study of the helium induced fine structure observed in electronic spectra of anthracene derivatives with particular emphasis on a spectrally sharp multiplet splitting at the electronic origin. In addition to previously discussed species, 9-cyanoanthracene and 9-chloroanthracene will be presented in this study for the first time

The future of helium as a natural resource

CERN Document Server

Glowacki, Bartek A; Nuttall, William J

2012-01-01

The book reveals the changing dynamics of the helium industry on both the supply-side and the demand-side. The helium industry has a long-term future and this important gas will have a role to play for many decades to come. Major new users of helium are expected to enter the market, especially in nuclear energy (both fission and fusion). Prices and volumes supplied and expected to rise and this will prompt greater efforts towards the development of new helium sources and helium conservation and recycling.

Robe Development for Electrical Conductivity Analysis in an Electron Gun Produced Helium Plasma

Science.gov (United States)

Bragg-Sitton, Shannon M.; Bitteker, Leo; Rodgers, Stephen L. (Technical Monitor)

2002-01-01

The use of magnetohydrodynamic (MHD) power conversion systems, potentially coupled with a fission power source, is currently being investigated as a driver for an advanced propulsion system, such as a plasma thruster. The efficiency of a MHD generator is strongly dependent on the electrical conductivity of the fluid that passes through the generator; power density increases as fluid conductivity increases. Although traditional MHD flows depend on thermal ionization to enhance the electrical conductivity, ionization due to nuclear interactions may achieve a comparable or improved conductivity enhancement while avoiding many of the limitations inherent to thermal ionization. Calculations suggest that nuclear-enhanced electrical conductivity increases as the neutron flux increases; conductivity of pure He-3 greater than 10 mho/m may be achievable if exposed to a flux greater than 10(exp 12) neutrons/cm2/s.) However, this remains to be demonstrated experimentally. An experimental facility has been constructed at the Propulsion Research Center at the NASA Marshall Space Flight Center, using helium as the test fluid. High energy electrons will be used to simulate the effects of neutron-induced ionization of helium gas to produce a plasma. These experiments will be focused on diagnosis of the plasma in a virtually static system; results will be applied to future tests with a MHD system. Initial experiments will utilize a 50 keV electron gun that can operate at up to a current of 200 micro A. Spreading the electron beam over a four inch diameter window results in an electron flux of 1.5x 10(exp 13) e/sq cm/s. The equivalent neutron flux that would produce the same ionization fraction in helium is 1x10(exp 12) n/sq cm/s. Experiments will simulate the neutron generated plasma modeled by Bitteker, which takes into account the products of thermal neutron absorption in He-3, and includes various ion species in estimating the conductivity of the resulting plasma. Several

Electronic properties of physisorbed helium

International Nuclear Information System (INIS)

Kossler, Sarah

2011-01-01

This thesis deals with electronic excitations of helium physisorbed on metal substrates. It is studied to what extent the electronic properties change compared to the gas phase due to the increased helium density and the proximity of the metal. Furthermore, the influence of different substrate materials is investigated systematically. To this end, up to two helium layers were adsorbed onto Ru (001), Pt (111), Cu (111), and Ag (111) surfaces in a custom-made cryostat. These samples were studied spectroscopically using synchrotron radiation and a time-of-flight detector. The experimental results were then analyzed in comparison with extensive theoretical model calculations.

Electronic properties of physisorbed helium

Energy Technology Data Exchange (ETDEWEB)

Kossler, Sarah

2011-09-22

This thesis deals with electronic excitations of helium physisorbed on metal substrates. It is studied to what extent the electronic properties change compared to the gas phase due to the increased helium density and the proximity of the metal. Furthermore, the influence of different substrate materials is investigated systematically. To this end, up to two helium layers were adsorbed onto Ru (001), Pt (111), Cu (111), and Ag (111) surfaces in a custom-made cryostat. These samples were studied spectroscopically using synchrotron radiation and a time-of-flight detector. The experimental results were then analyzed in comparison with extensive theoretical model calculations.

The Contribution of Working Memory to Fluid Reasoning: Capacity, Control, or Both?

Science.gov (United States)

Chuderski, Adam; Necka, Edward

2012-01-01

Fluid reasoning shares a large part of its variance with working memory capacity (WMC). The literature on working memory (WM) suggests that the capacity of the focus of attention responsible for simultaneous maintenance and integration of information within WM, as well as the effectiveness of executive control exerted over WM, determines…

Influence of working fluids on Organic Rankine Cycle for waste heat recovery applications

Energy Technology Data Exchange (ETDEWEB)

Struzyna, Ralf; Eifler, Wolfgang; Steinmill, Jens [Bochum Univ. (Germany). Lehrstuhl fuer Verbrennungsmotoren

2012-11-01

More than 50% of the energy contained in fuel is lost due to the loss of heat content to the exhaust gas, the cooling water or the charge air cooler medium. Therefore, one of the most promising attempts to further increase the efficiency of internal combustion engines is waste heat recovery by means of a combined process. The Organic Rankine Cycle (ORC) is a promising process for waste heat recovery systems. The main purpose is to identify suitable working fluids to achieve best system performance. Therefore an analysis of the influence of different working fluids on system output is required. (orig.)

Working memory capacity and fluid abilities: The more difficult the item, the more more is better

OpenAIRE

Daniel R Little; Stephan eLewandowsky; Stephan eLewandowsky; Stewart eCraig

2014-01-01

The relationship between fluid intelligence and working memory is of fundamental importance to understanding how capacity-limited structures such as working memory interact with inference abilities to determine intelligent behaviour. Recent evidence has suggested that the relationship between a fluid abilities test, Raven's Progressive Matrices, and working memory capacity (WMC) may be invariant across difficulty levels of the Raven's items. We show that this invariance can only be observed i...

Integrated working fluid-thermodynamic cycle design of organic Rankine cycle power systems for waste heat recovery

DEFF Research Database (Denmark)

Cignitti, Stefano; Andreasen, Jesper Graa; Haglind, Fredrik

2017-01-01

recovery. Inthis paper, an organic Rankine cycle process and its pure working fluid are designed simultaneously forwaste heat recovery of the exhaust gas from a marine diesel engine. This approach can overcome designissues caused by the high sensitivity between the fluid and cycle design variables......Today, some established working fluids are being phased out due to new international regulations on theuse of environmentally harmful substances. With an ever-increasing cost to resources, industry wants toconverge on improved sustainability through resource recovery, and in particular waste heat...

Helium behaviour in UO{sub 2} through low fluence ion implantation studies

Energy Technology Data Exchange (ETDEWEB)

Garcia, P., E-mail: philippe.garcia@cea.fr [CEA – DEN/DEC, Bât. 352, 13108 Saint-Paul-Lez-Durance Cedex (France); Gilabert, E. [Centre d’Et' udes Nucleáires de Bordeaux-Gradignan, Le Haut Vigneau, 33175 Gradignan (France); Martin, G.; Carlot, G.; Sabathier, C. [CEA – DEN/DEC, Bât. 352, 13108 Saint-Paul-Lez-Durance Cedex (France); Sauvage, T.; Desgardin, P.; Barthe, M.-F. [CNRS-CEMHTI, UPR3079, 45071 Orleáns (France)

2014-05-01

In this work we focus on experiments involving implantation of 500 keV {sup 3}He ions in sintered polycrystalline material. Samples are implanted at low fluences (∼2 ×10{sup 13} ions/cm{sup 2}) and subsequently isothermally annealed in a highly sensitive thermal desorption spectrometry (TDS) device PIAGARA (Plateforme Interdisciplinaire pour l’Analyse des GAz Rares en Aquitaine). The helium fluencies studied are two to three orders of magnitude lower than previous Nuclear Reaction Analysis (NRA) experiments carried out on identical samples implanted at identical energies. The fractional release of helium obtained in the TDS experiments is interpreted using a three-dimensional axisymmetric diffusion model which enables results to be quantitatively compared to previous NRA data. The analysis shows that helium behaviour is qualitatively independent of ion fluency over three orders of magnitude: helium diffusion appears to be strongly inhibited below 1273 K within the centre of the grains presumably as a result of helium bubble precipitation. The scenario involving diffusion at grain boundaries and in regions adjacent to them observed at higher fluencies is quantitatively confirmed at much lower doses. The main difference lies in the average width of the region in which uninhibited diffusion occurs.

Open Loop Heat Pipe Radiator Having a Free-Piston for Wiping Condensed Working Fluid

Science.gov (United States)

Weinstein, Leonard M. (Inventor)

2015-01-01

An open loop heat pipe radiator comprises a radiator tube and a free-piston. The radiator tube has a first end, a second end, and a tube wall, and the tube wall has an inner surface and an outer surface. The free-piston is enclosed within the radiator tube and is capable of movement within the radiator tube between the first and second ends. The free-piston defines a first space between the free-piston, the first end, and the tube wall, and further defines a second space between the free-piston, the second end, and the tube wall. A gaseous-state working fluid, which was evaporated to remove waste heat, alternately enters the first and second spaces, and the free-piston wipes condensed working fluid from the inner surface of the tube wall as the free-piston alternately moves between the first and second ends. The condensed working fluid is then pumped back to the heat source.

Laser spectroscopy of antiprotonic helium

CERN Document Server

Hori, M

2005-01-01

When antiprotons (i.e. the antimatter counterpart of protons) are stopped in helium gas, 97% of them annihilate within picoseconds by reacting with the helium nuclei; a 3% fraction, however, survive with an anomalously long lifetime of several microseconds. This longevity is due to the formation of antiprotonic helium, which is a three-body Rydberg atom composed of an antiproton, electron, and helium nucleus. The ASACUSA experimental collaboration has recently synthesized large numbers of these atoms using CERN's Antiproton Decelerator facility, and measured the atom's transition frequencies to 60 parts per billion by laser spectroscopy. By comparing the experimental results with recent three-body QED calculations and the known antiproton cyclotron frequency, we were able to show that the antiproton mass and charge are the same as the corresponding proton values to a precision of 10 parts per billion. Ongoing and future series of experiments will further improve the experimental precision by using chirp-compe...

Computer program for computing the properties of seventeen fluids. [cryogenic liquids

Science.gov (United States)

Brennan, J. A.; Friend, D. G.; Arp, V. D.; Mccarty, R. D.

1992-01-01

The present study describes modifications and additions to the MIPROPS computer program for calculating the thermophysical properties of 17 fluids. These changes include adding new fluids, new properties, and a new interface to the program. The new program allows the user to select the input and output parameters and the units to be displayed for each parameter. Fluids added to the MIPROPS program are carbon dioxide, carbon monoxide, deuterium, helium, normal hydrogen, and xenon. The most recent modifications to the MIPROPS program are the addition of viscosity and thermal conductivity correlations for parahydrogen and the addition of the fluids normal hydrogen and xenon. The recently added interface considerably increases the program's utility.

Femtosecond spectroscopy on alkali-doped helium nanodroplets; Femtosekundenspektroskopie an alkalidotierten Helium-Nanotroepfchen

Energy Technology Data Exchange (ETDEWEB)

Claas, P.

2006-01-15

In the present thesis first studies on the short-time dynamics in alkali dimers and microclusters, which were bound on the surface of superfluid helium droplets, were presented. The experiments comprehended pump-probe measurements on the fs scale on the vibration dynamics on the dimers and on the fragmentation dynamics on the clusters. Generally by the studies it was shown that such extremely short slopes can also be observed on helium droplets by means of the femtosecond spectroscopy.

Selection of Optimum Working Fluid for Organic Rankine Cycles by Exergy and Exergy-Economic Analyses

Directory of Open Access Journals (Sweden)

Kamyar Darvish

2015-11-01

Full Text Available The thermodynamic performance of a regenerative organic Rankine cycle that utilizes low temperature heat sources to facilitate the selection of proper organic working fluids is simulated. Thermodynamic models are used to investigate thermodynamic parameters such as output power, and energy efficiency of the ORC (Organic Rankine Cycle. In addition, the cost rate of electricity is examined with exergo-economic analysis. Nine working fluids are considered as part of the investigation to assess which yields the highest output power and exergy efficiency, within system constraints. Exergy efficiency and cost rate of electricity are used as objective functions for system optimization, and each fluid is assessed in terms of the optimal operating condition. The degree of superheat and the pressure ratio are independent variables in the optimization. R134a and iso-butane are found to exhibit the highest energy and exergy efficiencies, while they have output powers in between the systems using other working fluids. For a source temperature was equal to 120 °C, the exergy efficiencies for the systems using R134a and iso-butane are observed to be 19.6% and 20.3%, respectively. The largest exergy destructions occur in the boiler and the expander. The electricity cost rates for the system vary from 0.08 USD/kWh to 0.12 USD/kWh, depending on the fuel input cost, for the system using R134a as a working fluid.

Serial single molecule electron diffraction imaging: diffraction background of superfluid helium droplets

Science.gov (United States)

Zhang, Jie; He, Yunteng; Lei, Lei; Alghamdi, Maha; Oswalt, Andrew; Kong, Wei

2017-08-01

In an effort to solve the crystallization problem in crystallography, we have been engaged in developing a method termed "serial single molecule electron diffraction imaging" (SS-EDI). The unique features of SS-EDI are superfluid helium droplet cooling and field-induced orientation: together the two features constitute a molecular goniometer. Unfortunately, the helium atoms surrounding the sample molecule also contribute to a diffraction background. In this report, we analyze the properties of a superfluid helium droplet beam and its doping statistics, and demonstrate the feasibility of overcoming the background issue by using the velocity slip phenomenon of a pulsed droplet beam. Electron diffraction profiles and pair correlation functions of ferrocene-monomer-doped droplets and iodine-nanocluster-doped droplets are presented. The timing of the pulsed electron gun and the effective doping efficiency under different dopant pressures can both be controlled for size selection. This work clears any doubt of the effectiveness of superfluid helium droplets in SS-EDI, thereby advancing the effort in demonstrating the "proof-of-concept" one step further.

The adsorption of helium atoms on coronene cations

Energy Technology Data Exchange (ETDEWEB)

Kurzthaler, Thomas; Rasul, Bilal; Kuhn, Martin; Scheier, Paul, E-mail: Paul.Scheier@uibk.ac.at, E-mail: andrew.ellis@le.ac.uk [Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck (Austria); Lindinger, Albrecht [Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin (Germany); Ellis, Andrew M., E-mail: Paul.Scheier@uibk.ac.at, E-mail: andrew.ellis@le.ac.uk [Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom)

2016-08-14

We report the first experimental study of the attachment of multiple foreign atoms to a cationic polycyclic aromatic hydrocarbon (PAH). The chosen PAH was coronene, C{sub 24}H{sub 12}, which was added to liquid helium nanodroplets and then subjected to electron bombardment. Using mass spectrometry, coronene cations decorated with helium atoms were clearly seen and the spectrum shows peaks with anomalously high intensities (“magic number” peaks), which represent ion-helium complexes with added stability. The data suggest the formation of a rigid helium layer consisting of 38 helium atoms that completely cover both faces of the coronene ion. Additional magic numbers can be seen for the further addition of 3 and 6 helium atoms, which are thought to attach to the edge of the coronene. The observation of magic numbers for the addition of 38 and 44 helium atoms is in good agreement with a recent path integral Monte Carlo prediction for helium atoms on neutral coronene. An understanding of how atoms and molecules attach to PAH ions is important for a number of reasons including the potential role such complexes might play in the chemistry of the interstellar medium.

Helium release from radioisotope heat sources

Energy Technology Data Exchange (ETDEWEB)

Peterson, D.E.; Early, J.W.; Starzynski, J.S.; Land, C.C.

1984-05-01

Diffusion of helium in /sup 238/PuO/sub 2/ fuel was characterized as a function of the heating rate and the fuel microstructure. The samples were thermally ramped in an induction furnace and the helium release rates measured with an automated mass spectrometer. The diffusion constants and activation energies were obtained from the data using a simple diffusion model. The release rates of helium were correlated with the fuel microstructure by metallographic examination of fuel samples. The release mechanism consists of four regimes, which are dependent upon the temperature. Initially, the release is controlled by movement of point defects combined with trapping along grain boundaries. This regime is followed by a process dominated by formation and growth of helium bubbles along grain boundaries. The third regime involves volume diffusion controlled by movement of oxygen vacancies. Finally, the release at the highest temperatures follows the diffusion rate of intragranular bubbles. The tendency for helium to be trapped within the grain boundaries diminishes with small grain sizes, slow thermal pulses, and older fuel.

Recent developments in liquid helium 3

International Nuclear Information System (INIS)

Ramarao, I.

1977-01-01

The current status of the theories for the ground state of liquid helium 3, are reviewed. To begin with, a brief summary of the experimental results on the thermodynamic properties of liquid helium 3 including its recently discovered superfulid phases is given. The basic ideas of the Landau theory of a normal Fermi liquid are then introduced. A qualitative discussion of the current understanding of the anisotropic phases of superfluid helium 3 is given, the microscopic calculaations for the binding energy of liquid helium 3 are reviewed and the results obtained for the two-body contributions to the binding energy using the Brueckner-Goldstone formulation and that of Mohling and his collaborators are summarized and discussed. The importance of a proper estimate of the three-body contributions to the binding energy is stressed. The results obtained in the literature using variational methods and constrained variational methods are discussed. A critical analysis of the results by various methods is given. Despite much effort the basic problem of the ground state of liquid helium 3, remains unresolved. (author)

Helium release from radioisotope heat sources

International Nuclear Information System (INIS)

Peterson, D.E.; Early, J.W.; Starzynski, J.S.; Land, C.C.

1984-05-01

Diffusion of helium in 238 PuO 2 fuel was characterized as a function of the heating rate and the fuel microstructure. The samples were thermally ramped in an induction furnace and the helium release rates measured with an automated mass spectrometer. The diffusion constants and activation energies were obtained from the data using a simple diffusion model. The release rates of helium were correlated with the fuel microstructure by metallographic examination of fuel samples. The release mechanism consists of four regimes, which are dependent upon the temperature. Initially, the release is controlled by movement of point defects combined with trapping along grain boundaries. This regime is followed by a process dominated by formation and growth of helium bubbles along grain boundaries. The third regime involves volume diffusion controlled by movement of oxygen vacancies. Finally, the release at the highest temperatures follows the diffusion rate of intragranular bubbles. The tendency for helium to be trapped within the grain boundaries diminishes with small grain sizes, slow thermal pulses, and older fuel

Cosmological helium production simplified

International Nuclear Information System (INIS)

Bernstein, J.; Brown, L.S.; Feinberg, G.

1988-01-01

We present a simplified model of helium synthesis in the early universe. The purpose of the model is to explain clearly the physical ideas relevant to the cosmological helium synthesis, in a manner that does not overlay these ideas with complex computer calculations. The model closely follows the standard calculation, except that it neglects the small effect of Fermi-Dirac statistics for the leptons. We also neglect the temperature difference between photons and neutrinos during the period in which neutrons and protons interconvert. These approximations allow us to express the neutron-proton conversion rates in a closed form, which agrees to 10% accuracy or better with the exact rates. Using these analytic expressions for the rates, we reduce the calculation of the neutron-proton ratio as a function of temperature to a simple numerical integral. We also estimate the effect of neutron decay on the helium abundance. Our result for this quantity agrees well with precise computer calculations. We use our semi-analytic formulas to determine how the predicted helium abundance varies with such parameters as the neutron life-time, the baryon to photon ratio, the number of neutrino species, and a possible electron-neutrino chemical potential. 19 refs., 1 fig., 1 tab

Low-temperature centrifugal helium compressor

International Nuclear Information System (INIS)

Kawada, M.; Togo, S.; Akiyama, Y.; Wada, R.

1974-01-01

A centrifugal helium compressor with gas bearings, which can be operated at the temperature of liquid nitrogen, has been investigated. This compressor has the advantages that the compression ratio should be higher than the room temperature operation and that the contamination of helium could be eliminated. The outer diameter of the rotor is 112 mm. The experimental result for helium gas at low temperature shows a flow rate of 47 g/s and a compression ratio of 1.2 when the inlet pressure was 1 ata and the rotational speed 550 rev/s. The investigation is now focused on obtaining a compression ratio of 1.5. (author)

An organic group contribution approach to radiative efficiency estimation of organic working fluid

International Nuclear Information System (INIS)

Zhang, Xinxin; Kobayashi, Noriyuki; He, Maogang; Wang, Jingfu

2016-01-01

Highlights: • We use group contribution method to estimate radiative efficiency. • CFC, HCFC, HFC, HFE, and PFC were estimated using this method. • In most cases, the estimation value has a good precision. • The method is reliable for the estimation of molecule with a symmetric structure. • This estimation method can offer good reference for working fluid development. - Abstract: The ratification of the Montreal Protocol in 1987 and the Kyoto Protocol in 1997 mark an environment protection era of the development of organic working fluid. Ozone depletion potential (ODP) and global warming potential (GWP) are two most important indices for the quantitative comparison of organic working fluid. Nowadays, more and more attention has been paid to GWP. The calculation of GWP is an extremely complicated process which involves interactions between surface and atmosphere such as atmospheric radiative transfer and atmospheric chemical reactions. GWP of a substance is related to its atmospheric abundance and is a variable in itself. However, radiative efficiency is an intermediate parameter for GWP calculation and it is a constant value used to describe inherent property of a substance. In this paper, the group contribution method was adopted to estimate the radiative efficiency of the organic substance which contains more than one carbon atom. In most cases, the estimation value and the standard value are in a good agreement. The biggest estimation error occurs in the estimation of the radiative efficiency of fluorinated ethers due to its plenty of structure groups and its complicated structure compared with hydrocarbon. This estimation method can be used to predict the radiative efficiency of newly developed organic working fluids.

Retention of hydrogen isotopes and helium in nickel

Energy Technology Data Exchange (ETDEWEB)

Okada, Mitsumasa; Sato, Rikiya; Yamaguchi, Kenji; Yamawaki, Michio [Tokyo Univ., Tokai, Ibaraki (Japan). Nuclear Engineering Research Lab.

1996-10-01

In the present study, a thin foil of nickel was irradiated by H{sub 2}{sup +}, D{sub 2}{sup +} and He{sup +} to a fluence of 1.2-6.0x10{sup 20}/m{sup 2} using the TBTS (Tritium Beam Test System) apparatus. The thermal desorption spectroscopy (TDS) technique was employed to evaluate the total amount of retained hydrogen isotope and helium atoms in nickel. In the spectra, two peaks appeared at 440-585K and 720-735K for helium. Hydrogen isotopes irradiation after helium preirradiation were found to enhance the helium release and to decrease the peak temperatures. Helium irradiation after hydrogen isotopes preirradiation were found to enhance the helium release, but the peak temperature showed little difference from that without preirradiation. (author)

Improving the economy-of-scale of small organic rankine cycle systems through appropriate working fluid selection

International Nuclear Information System (INIS)

White, Martin; Sayma, Abdulnaser I.

2016-01-01

Highlights: • Novel system model coupling turbine and ORC system performance. • Contour plots to characterise working fluid and turbine performance. • Changing working fluid can expand pump and turbine operating envelope. • Possible to improve the economy-of-scale through optimal working fluid selection. - Abstract: Organic Rankine cycles (ORC) are becoming a major research area within the field of sustainable energy systems. However, a major challenge facing the widespread implementation of small and mini-scale ORC systems is the economy-of-scale. To overcome this challenge requires single components that can be manufactured in large volumes and then implemented into a wide variety of different applications where the heat source conditions may vary. The aim of this paper is to investigate whether working fluid selection can improve the current economy-of-scale by enabling the same system components to be used in multiple ORC systems. This is done through coupling analysis and optimisation of the energy process, with a performance map for a small-scale ORC radial turbine. The performance map, obtained using CFD, is adapted to account for additional loss mechanisms not accounted for in the original CFD simulation before being non-dimensionalised using a modified similitude theory developed for subsonic ORC turbines. The updated performance map is then implemented into a thermodynamic model, enabling the construction of a single performance contour that displays the range of heat source conditions that can be accommodated by the existing turbine whilst using a particular working fluid. Constructing this performance map for a range of working fluids, this paper demonstrates that through selecting a suitable working fluid, the same turbine can efficiently utilise heat sources between 360 and 400 K, with mass flow rates ranging between 0.5 and 2.75 kg/s respectively. This corresponds to using the same turbine in ORC applications where the heat available ranges

Helium sources to groundwater in active volcanic terrain, and implications for tritium-helium dating at Mount St. Helens

Energy Technology Data Exchange (ETDEWEB)

Gates, John B. [Department of Earth and Atmospheric Sciences, University of Nebraska-Lincoln, 217 Bessey Hall, Lincoln NE 68588 (United States)

2013-07-01

Groundwater helium sources and residence times were investigated using groundwater discharging from springs surrounding Mount St. Helens in the Cascades region of the United States. Significant contributions of mantle helium were found in all samples and are attributable to interaction between groundwater and magmatic gases. Bounding calculations for residence times were made on the basis of helium isotope mixing plots and historical tritium data. (authors)

Boiling of multicomponent working fluids used in refrigeration and cryogenic systems

Science.gov (United States)

Mogorychny, V. I.; Dolzhikov, A. S.

2017-11-01

Working fluids based on mixtures are widely used in cryogenic and refrigeration engineering. One of the main elements of low-temperature units is a recuperative heat exchanger where the return flow cools the direct (cold regeneration is carrying out) resulting in continuous boiling and condensation of the multicomponent working fluid in the channels. The temperature difference between the inlet and outlet of the heat exchanger can be more than 100K, which leads to a strong change in thermophysical properties along its length. In addition, the fraction of the liquid and vapor phases in the flow varies very much, which affects the observed flow regimes in the heat exchanger channels. At the moment there are not so many experimental data and analytical correlations that would allow to estimate the heat transfer coefficient during the flow of a two-phase mixture flow at low temperatures. The work is devoted to the study of the boiling process of multicomponent working fluids used in refrigeration and cryogenic engineering. The description of the method of determination of heat transfer coefficient during boiling of mixtures in horizontal heated channel is given as well as the design of the experimental stand allowing to make such measurements. This stand is designed on the basis of a refrigeration unit operating on the Joule-Thomson throttle cycle and makes it possible to measure the heat transfer coefficient with a good accuracy. Also, the calculated values of the heat transfer coefficient, obtained with the use of various correlations, are compared with the existing experimental data. Knowing of the heat transfer coefficient will be very useful in the design of heat exchangers for low-temperature units operating on a mixture refrigerant.

Explosive helium burning in white dwarf stars

Energy Technology Data Exchange (ETDEWEB)

Khokhlov, A.M. (AN SSSR, Moscow. Astronomicheskij Sovet)

1984-04-01

Helium burning kinetics in white dwarfs has been considered at constant temperatures T >= 10/sup 9/ K and densities rho >10/sup 5/ g/cm/sup 3/. It is found, that helium detonation in white dwarfs does not lead to formation of light (A < 56) elements. Thus, helium white dwarf model for supernova 1 is inconsistent with observations.

A new helium gas recovery and purification system

International Nuclear Information System (INIS)

Yamamotot, T.; Suzuki, H.; Ishii, J.; Hamana, I.; Hayashi, S.; Mizutani, S.; Sanjo, S.

1974-01-01

A helium gas recovery and purification system, based on the principle of gas permeation through a membrane, is described. The system can be used for the purification of helium gas containing air as a contaminant. The apparatus, operating at ambient temperature does not need constant attention, the recovery ratio of helium gas is satisfactory and running costs are low. Gases other than helium can be processed with the apparatus. (U.K.)

Helium leak and chemical impurities control technology in HTTR

International Nuclear Information System (INIS)

Tochio, Daisuke; Shimizu, Atsushi; Hamamoto, Shimpei; Sakaba, Nariaki

2014-01-01

Japan Atomic Energy Agency (JAEA) has designed and developed high-temperature gas-cooled reactor (HTGR) hydrogen cogeneration system named gas turbine high-temperature reactor (GTHTR300C) as a commercial HTGR. Helium gas is used as the primary coolant in HTGR. Helium gas is easy to leak, and the primary helium leakage should be controlled tightly from the viewpoint of preventing the release of radioactive materials to the environment. Moreover from the viewpoint of preventing the oxidization of graphite and metallic material, the helium coolant chemistry should be controlled tightly. The primary helium leakage and the helium coolant chemistry during the operation is the major factor in the HTGR for commercialization of HTGR system. This paper shows the design concept and the obtained operational experience on the primary helium leakage control and primary helium impurity control in the high-temperature engineering test reactor (HTTR) of JAEA. Moreover, the future plan to obtain operational experience of these controls for commercialization of HTGR system is shown. (author)

Equivalent isentropic expansion efficiency of real fluid subject to concurrent pressure drop and heat transfer

Science.gov (United States)

Knudsen, P.; Ganni, V.

2017-12-01

Concurrent pressure drop and cooling of a super-critical or sub-cooled liquid stream can have the same effect as adiabatic expansion even though there is no work extraction. A practical implementation is as straight forward as counter-flow heat exchange with a colder fluid. The concurrent pressure drop need not be continuous with respect to the heat exchange, but may occur in a step-wise manner, in between heat exchange. Two aspects of this effect of pressure drop with heat transfer are examined; a thermodynamic and a practical process equivalent isentropic expansion efficiency. This real fluid phenomenon is useful to understand in applications where work extraction is either not practical or has not been developed. A super-critical helium supply, often around 3 bar and 4.5 K, being ultimately used as a superfluid (usually around 1.8 to 2.1 K) to cool a Niobium superconducting radio frequency cavity or a superconducting magnet is one such particular application. This paper examines the thermodynamic nature of this phenomenon.

Helium heater design for the helium direct cycle component test facility. [for gas-cooled nuclear reactor power plant

Science.gov (United States)

Larson, V. R.; Gunn, S. V.; Lee, J. C.

1975-01-01

The paper describes a helium heater to be used to conduct non-nuclear demonstration tests of the complete power conversion loop for a direct-cycle gas-cooled nuclear reactor power plant. Requirements for the heater include: heating the helium to a 1500 F temperature, operating at a 1000 psia helium pressure, providing a thermal response capability and helium volume similar to that of the nuclear reactor, and a total heater system helium pressure drop of not more than 15 psi. The unique compact heater system design proposed consists of 18 heater modules; air preheaters, compressors, and compressor drive systems; an integral control system; piping; and auxiliary equipment. The heater modules incorporate the dual-concentric-tube 'Variflux' heat exchanger design which provides a controlled heat flux along the entire length of the tube element. The heater design as proposed will meet all system requirements. The heater uses pressurized combustion (50 psia) to provide intensive heat transfer, and to minimize furnace volume and heat storage mass.

Performance characterization of the FLEX low pressure helium facility for fusion technology experiments

Energy Technology Data Exchange (ETDEWEB)

Schlindwein, Georg, E-mail: schlindwein@kit.edu; Arbeiter, Frederik

2014-10-15

Highlights: • A gas loop for fusion R and D has been built and tested. • Facility requirements and their implementation are given. • The loop's functions and instrumentation are explained. • The loops performance has been characterized. - Abstract: FLEX (Fluid Dynamics Experimental Facility) is a multi-purpose small scale gas loop for research on fluid and thermodynamic investigations, especially heat transfer, flow field measurements and gas purification. Initially it was built for investigation on mini-channel gas-flow to design the HFTM module of IFMIF. Because of its versatility it offers a wide range of further applications, e.g. the research of pressure drops in mockups of breeder units of the helium cooled pebble bed (HCPB) test blanket module for ITER. The main parameters of the loop, which can be operated with inert gases and air are: (i) operation gas pressure 0.02–0.38 MPa abs., (ii) test section pressure head up to 0.12 MPa, (iii) tolerable gas temperature RT – 200 °C and (iv) mass flow rate 0.2–12 × 10{sup −3} kg/s for Helium. This paper gives a detailed view of the loop assembly with the components that generate and regulate the mass flow and loop pressure. The measurement instrumentation will be presented as well as a representative mass flow-pressure drop characteristic. Furthermore, the achievable gas purity will be discussed.

Defects induced by helium implantation in SiC

International Nuclear Information System (INIS)

Oliviero, E.; Barbot, J.F.; Declemy, A.; Beaufort, M.F.; Oliviero, E.

2008-01-01

SiC is one of the considered materials for nuclear fuel conditioning and for the fabrication of some core structures in future nuclear generation reactors. For the development of this advance technology, a fundamental research on this material is of prime importance. In particular, the implantation/irradiation effects have to be understood and controlled. It is with this aim that the structural alterations induced by implantation/irradiation in SiC are studied by different experimental techniques as transmission electron microscopy, helium desorption, X-ray diffraction and Rutherford backscattering spectrometry. In this work, the different types of defects induced by helium implantation in SiC, point or primary defects (obtained at low energy (∼100 eV) until spread defects (obtained at higher energy (until ∼2 MeV)) are exposed. The amorphization/recrystallization and swelling phenomena are presented too. (O.M.)

A multi-objective optimization approach for the selection of working fluids of geothermal facilities: Economic, environmental and social aspects.

Science.gov (United States)

Martínez-Gomez, Juan; Peña-Lamas, Javier; Martín, Mariano; Ponce-Ortega, José María

2017-12-01

The selection of the working fluid for Organic Rankine Cycles has traditionally been addressed from systematic heuristic methods, which perform a characterization and prior selection considering mainly one objective, thus avoiding a selection considering simultaneously the objectives related to sustainability and safety. The objective of this work is to propose a methodology for the optimal selection of the working fluid for Organic Rankine Cycles. The model is presented as a multi-objective approach, which simultaneously considers the economic, environmental and safety aspects. The economic objective function considers the profit obtained by selling the energy produced. Safety was evaluated in terms of individual risk for each of the components of the Organic Rankine Cycles and it was formulated as a function of the operating conditions and hazardous properties of each working fluid. The environmental function is based on carbon dioxide emissions, considering carbon dioxide mitigation, emission due to the use of cooling water as well emissions due material release. The methodology was applied to the case of geothermal facilities to select the optimal working fluid although it can be extended to waste heat recovery. The results show that the hydrocarbons represent better solutions, thus among a list of 24 working fluids, toluene is selected as the best fluid. Copyright © 2017 Elsevier Ltd. All rights reserved.

Kinetic energy dissipation of a tuning fork immersed in superfluid helium at different frequencies of oscillations

International Nuclear Information System (INIS)

Gritsenko, I.A.; Klokol, K.A.; Sokolov, S.S.; Sheshin, G.A.

2016-01-01

An experimental study is made of the drag coefficient, which is the characteristics of energy dissipation during oscillations of the tuning forks, immersed in liquid helium. The experiments were performed in the temperature range from 0.1 to 3.5 K covering both the range of a hydrodynamic flow, and the ballistic regime of transfer of thermal excitations of superfluid helium below 0.6 K. It is found that there is the frequency dependence of the drag coefficient in the hydrodynamic limit, when the main dissipation mechanism is the viscous friction of the fluid against the walls of the oscillating body at temperatures above 0.7 K. In this case, the drag coefficient is proportional to the square root of the frequency of oscillation, and its temperature dependence in He II is determined by the respective dependence of the normal component density of the normal component and the viscosity of the fluid. At lower temperatures, the dependence of drag coefficient on the frequency is not available, and the magnitude of the dissipative losses is determined only by the temperature dependence of the density of the normal component. At the same time in the entire range of temperatures value of dissipative losses depends on the geometry of the oscillating body.

Study on Mixed Working Fluids with Different Compositions in Organic Rankine Cycle (ORC Systems for Vehicle Diesel Engines

Directory of Open Access Journals (Sweden)

Kai Yang

2014-08-01

Full Text Available One way to increase the thermal efficiency of vehicle diesel engines is to recover waste heat by using an organic Rankine cycle (ORC system. Tests were conducted to study the running performances of diesel engines in the whole operating range. The law of variation of the exhaust energy rate under various engine operating conditions was also analyzed. A diesel engine-ORC combined system was designed, and relevant evaluation indexes proposed. The variation of the running performances of the combined system under various engine operating conditions was investigated. R245fa and R152a were selected as the components of the mixed working fluid. Thereafter, six kinds of mixed working fluids with different compositions were presented. The effects of mixed working fluids with different compositions on the running performances of the combined system were revealed. Results show that the running performances of the combined system can be improved effectively when mass fraction R152a in the mixed working fluid is high and the engine operates with high power. For the mixed working fluid M1 (R245fa/R152a, 0.1/0.9, by mass fraction, the net power output of the combined system reaches the maximum of 34.61 kW. Output energy density of working fluid (OEDWF, waste heat recovery efficiency (WHRE, and engine thermal efficiency increasing ratio (ETEIR all reach their maximum values at 42.7 kJ/kg, 10.90%, and 11.29%, respectively.

A study of organic working fluids of an organic Rankine cycle for solar concentrating power plant

International Nuclear Information System (INIS)

Saifaoui, D.; Elmaanaoui, Y.; Faik, A.

2014-01-01

This work is a comparative study between four different configurations of an organic Rankine cycle (ORC) in order to find the configuration that gives the best performances. This study also made a comparison between seven organic fluids used as working fluids in the four ORC configurations. These fluids are all hydrocarbons. Then we made a parametric analysis of the results obtained in this first part. In a second part, we developed the binary mixtures of the seven pure hydrocarbons with the NIST software REFPROP 9 and we used them in our four ORC configurations. The obtained results are given and discussed. (author)

Closed-loop helium circulation system for actuation of a continuously operating heart catheter pump.

Science.gov (United States)

Karabegovic, Alen; Hinteregger, Markus; Janeczek, Christoph; Mohl, Werner; Gföhler, Margit

2017-06-09

Currently available, pneumatic-based medical devices are operated using closed-loop pulsatile or open continuous systems. Medical devices utilizing gases with a low atomic number in a continuous closed loop stream have not been documented to date. This work presents the construction of a portable helium circulation addressing the need for actuating a novel, pneumatically operated catheter pump. The design of its control system puts emphasis on the performance, safety and low running cost of the catheter pump. Static and dynamic characteristics of individual elements in the circulation are analyzed to ensure a proper operation of the system. The pneumatic circulation maximizes the working range of the drive unit inside the catheter pump while reducing the total size and noise production.Separate flow and pressure controllers position the turbine's working point into the stable region of the pressure creation element. A subsystem for rapid gas evacuation significantly decreases the duration of helium removal after a leak, reaching subatmospheric pressure in the intracorporeal catheter within several milliseconds. The system presented in the study offers an easy control of helium mass flow while ensuring stable behavior of its internal components.

On the disappearance of superfluidity in helium films

International Nuclear Information System (INIS)

Bannink, G.

1983-01-01

Experiments to investigate the changes in superfluid properties when helium films become thinner are reported. A thin-film oscillator, formed by two large filmreservoirs connected by a long and narrow tube, is used to study both the mass transport properties and the third-sound phenomena. Both sets of data are analysed in the framework of a two-fluid model. Absolute values for the areal superfluid density are deduced from the results, and also the observation of friction in the film itself is briefly discussed. A series of additional measurements of the thermo-mechanical effect in the reservoirs, with the purpose of determing the thickness at which onset of superfluidity occurs, are also reported. Finally the overall picture of the film properties is discussed on the basis of a phase diagram of the observed mobilities. (Auth.)

Effect of helium preinjection and prior thermomechanical treatment on the microstructure of Type 316 SS

International Nuclear Information System (INIS)

Kohyama, A.; Ayrault, G.; Turner, A.P.L.; Igata, N.

1982-10-01

Samples of 316 SS were preinjected with 15 appM helium either hot (650 0 C) or cold (room temperature) and irradiated with 3 MeV Ni + ions to a dose level of 25 dpa at 625 0 C in order to test the validity of helium preinjection as a means of simulation of transmutant helium production. Results for preinjected and single-ion irradiated samples were compared to samples irradiated with 3 MeV Ni + and simultaneously injected with helium at a rate of 15 appM He/dpa (dual-ion irradiated samples). Preinjected samples exhibited bimodal cavity size distributions. Preinjected samples of solution annealed or solution annealed and aged material showed lower swelling than dual-ion irradiated samples. However, He preinjection in 20% cold worked samples showed greater swelling than dual-ion irradiated samples 9 figures, 1 table

Study of Temperature Wave Propagation in Superfluid Helium Focusing on Radio-Frequency Cavity Cooling

CERN Document Server

Koettig, T; Avellino, S; Junginger, T; Bremer, J

2015-01-01

Oscillating Superleak Transducers (OSTs) can be used to localize quenches of superconducting radio-frequency cavities. Local hot spots at the cavity surface initiate temperature waves in the surrounding superfluid helium that acts as cooling fluid at typical temperatures in the range of 1.6 K to 2 K. The temperature wave is characterised by the properties of superfluid helium such as the second sound velocity. For high heat load densities second sound velocities greater than the standard literature values are observed. This fast propagation has been verified in dedicated small scale experiments. Resistors were used to simulate the quench spots under controlled conditions. The three dimensional propagation of second sound is linked to OST signals. The aim of this study is to improve the understanding of the OST signal especially the incident angle dependency. The characterised OSTs are used as a tool for quench localisation on a real size cavity. Their sensitivity as well as the time resolution was proven to b...

The TEXTOR helium self-pumping experiment: Design, plans, and supporting ion-beam data on helium retention in nickel

International Nuclear Information System (INIS)

Brooks, J.N.; Krauss, A.; Mattas, R.F.; Smith, D.L.; Nygren, R.E.; Doyle, B.L.; McGrath, R.T.; Walsh, D.; Dippel, K.H.; Finken, K.H.

1990-01-01

A proof-of-principle experiment to demonstrate helium self-pumping in a tokamak is being undertaken in TEXTOR. The experiment will use a helium self-pumping module installed in a modified ALT-I limiter head. The module consists of two, ≅ 25x25 cm 2 heated nickel alloy trapping plates, a nickel deposition filament array, and associated diagnostics. Between plasma shots a coating of ≅ 50A nickel will be deposited on the two trapping plates. During a shot helium and hydrogen ions will impinge on the plates through a ≅ 3 cm wide entrance slot. The helium removal capability, due to trapping in the nickel, will be assessed for a variety of plasma conditions. In support of the tokamak experiment, the trapping of helium over a range of ion fluences and surface temperatures, and detrapping during subsequent exposure to hydrogen, were measured in ion beam experiments using evaporated nickel surfaces similar to that expected in TEXTOR. Also, the retention of H and He after exposure of a nickel surface to mixed He/H plasmas has been measured. The results appear favorable, showing high helium trapping (≅ 10-50% He/Ni) and little or no detrapping by hydrogen. The TEXTOR experiment is planned to begin in 1991. (orig.)

The TEXTOR helium self-pumping experiment: Design, plans, and supporting ion-beam data on helium retention in nickel

International Nuclear Information System (INIS)

Brooks, J.N.; Krauss, A.; Mattas, R.F.; Smith, D.L.; Nygren, R.E.; Doyle, B.L.; McGrath, R.T.; Walsh, D.; Dippel, K.H.; Finken, K.H.

1990-01-01

A proof-of-principle experiment to demonstrate helium self-pumping in a tokamak is being undertaken in TEXTOR. The experiment will use a helium self-pumping module installed in a modified ALT-I limiter head. The module consists of two, ∼25 x 25 cm 2 heated nickel alloy trapping plates, a nickel deposition filament array, and associated diagnostics. Between plasma shots a coating of ∼50 angstrom nickel will be deposited on the two trapping plates. During a shot helium and hydrogen ions will impinge on the plates through a ∼3 cm wide entrance slot. The helium removal capability, due to trapping in the nickel, will be assessed for a variety of plasma conditions. In support of the tokamak experiment, the trapping of helium over a range of ion fluences and surface temperatures, and detrapping during subsequent exposure to hydrogen, were measured in ion beam experiments using evaporated nickel surfaces similar to that expected in TEXTOR. Also, the retention of H and He after exposure of a nickel surface to mixed He/H plasmas has bee measured. The results appear favorable, showing high helium trapping (∼10--50% He/Ni) and little or no detrapping by hydrogen. The TEXTOR experiment is planned to begin in 1991. 12 refs., 2 figs., 2 tabs

Sonic Helium Detectors in the Fermilab Tevatron

Science.gov (United States)

Bossert, R. J.

2006-04-01

In the Fermilab Tevatron cryogenic system there are many remotely located low-pressure plate relief valves that must vent large volumes of cold helium gas when magnet quenches occur. These valves can occasionally stick open or not reseat completely, resulting in a large helium loss. As such, the need exists for a detector to monitor the relief valve's discharge area for the presence of helium. Due to the quantity needed, cost is an important factor. A unit has been developed and built for this purpose that is quite inexpensive. Its operating principle is based on the speed of sound, where two closely matched tubes operate at their acoustic resonant frequency. When helium is introduced into one of these tubes, the resulting difference in acoustic time of flight is used to trigger an alarm. At present, there are 39 of these units installed and operating in the Tevatron. They have detected many minor and major helium leaks, and have also been found useful in detecting a rise in the helium background in the enclosed refrigerator buildings. This paper covers the construction, usage and operational experience gained with these units over the last several years.

Sonic helium detectors in the Fermilab Tevatron

International Nuclear Information System (INIS)

Bossert, R.J.; Fermilab

2006-01-01

In the Fermilab Tevatron cryogenic system there are many remotely located low-pressure plate relief valves that must vent large volumes of cold helium gas when magnet quenches occur. These valves can occasionally stick open or not reseat completely, resulting in a large helium loss. As such, the need exists for a detector to monitor the relief valve's discharge area for the presence of helium. Due to the quantity needed, cost is an important factor. A unit has been developed and built for this purpose that is quite inexpensive. Its operating principle is based on the speed of sound, where two closely matched tubes operate at their acoustic resonant frequency. When helium is introduced into one of these tubes, the resulting difference in acoustic time of flight is used to trigger an alarm. At present, there are 39 of these units installed and operating in the Tevatron. They have detected many minor and major helium leaks, and have also been found useful in detecting a rise in the helium background in the enclosed refrigerator buildings. This paper covers the construction, usage and operational experience gained with these units over the last several years

Helium production in reactor materials

International Nuclear Information System (INIS)

Lippincott, E.P.; McElroy, W.N.; Farrar, H. IV.

1975-02-01

Comparisons of integral helium production measurements with predictions based on ENDF/B Version IV cross sections have been made. It is concluded that an ENDF/B helium production cross section file should be established in order to ensure a complete and consistent cross section evaluation to meet accuracies required for LMFBR, CTR, and LWR applications. (U.S.)

Modeling Secondary Neutral Helium in the Heliosphere

International Nuclear Information System (INIS)

Müller, Hans-Reinhard; Möbius, Eberhard; Wood, Brian E.

2016-01-01

An accurate, analytic heliospheric neutral test-particle code for helium atoms from the interstellar medium (ISM) is coupled to global heliospheric models dominated by hydrogen and protons from the solar wind and the ISM. This coupling enables the forward-calculation of secondary helium neutrals from first principles. Secondaries are produced predominantly in the outer heliosheath, upwind of the heliopause, by charge exchange of helium ions with neutral atoms. The forward model integrates the secondary production terms along neutral trajectories and calculates the combined neutral helium phase space density in the innermost heliosphere where it can be related to in-situ observations. The phase space density of the secondary component is lower than that of primary neutral helium, but its presence can change the analysis of primaries and the ISM, and can yield valuable insight into the characteristics of the plasma in the outer heliosheath. (paper)

Use of helium in uranium exploration, Grants district

International Nuclear Information System (INIS)

DeVoto, R.H.; Mead, R.H.; Martin, J.P.; Bergquist, L.E.

1980-01-01

The continuous generation of inert helium gas from uranium and its daughter products provides a potentially useful means for remote detection of uranium deposits. The practicality of conducting helium surveys in the atmosphere, soil gas, and ground water to explore for buried uranium deposits has been tested in the Grants district and in the Powder River Basin of Wyoming. No detectable helium anomalies related to buried or surface uranium deposits were found in the atmosphere. However, reproducible helium-in-soil-gas anomalies were detected spatially related to uranium deposits buried from 50 to 800 ft deep. Diurnal and atmospheric effects can cause helium content variations (noise) in soil gas that are as great as the anomalies observed from instantaneous soil-gas samples. Cumulative soil-gas helium analyses, such as those obtained from collecting undisturbed soil samples and degassing them in the laboratory, may reveal anomalies from 5 to 100 percent above background. Ground water samples from the Grants district, New Mexico, and the Powder River Basin, Wyoming, have distinctly anomalous helium values spatially related to buried uranium deposits. In the southern Powder River Basin, helium values 20 to 200 percent above background occur 2 to 18 mile down the ground-water flow path from known uranium roll-front deposits. In the Grants district, helium contents 40 to 700 percent above background levels are present in ground waters from the host sandstone in the vicinity of uranium deposits and from aquifers up to 3,000 ft stratigraphically above the deep uranium deposits. The use of helium in soil and ground-water surveys, along with uranium and radon analyses of the same materials, is strongly recommended is expensive, deep, uranium-exploration programs such as those being conducted in the Grants district

Diagnostics of helium plasmas under special consideration of the continuous spectrum

International Nuclear Information System (INIS)

Einfeld, D.

1974-01-01

From measurements of the spectral beam density of the helium plasma in the region 290 nm to 650 nm, transition probabilities, Gaunt factors, line broadening parameters and deviations from the state of local thermodynamic equilibrium (L.T.E.) were determined and compared with theoretical data. Using the Gaunt factors experimentally secured in this work for the term n = 3, the electron density could be determined with an uncertainty of +-10% from the emission coefficients of the continuous spectrum. Assuming steady transition of the spectral emission coefficients over the series limit, a numerical method has been given according to which, amongst others, the Gaunt factors for the various series limits can be determined from the transition probabilities of these series. By determining the overpopulation factors of the ground states of the helium atom and the helium ion, a deviation from the L.T.E. state is experimentally detected and quantitatively described. (orig./LH) [de

Helium-plasma heating with a powerful proton beam for spectroscopic applications

International Nuclear Information System (INIS)

Arteev, M.S.; Kuznetsov, A.A.; Sulakshin, S.S.

1986-01-01

In this work the authors consider an ion gun which was especially developed for producing a gas plasma and report on the details of an experiment on (ELLIGIBLE) plasma spectroscopy. The current density of the proton beam was measured in the experiments on the axis of the gas tube with the aid of a collimating current collector with the wave impedance of a 75 omega cable. The ion gun was tested in the excitation of a helium plasma. Extremely pure helium with a pressure P = (0.2-1).10 5 Pa was employed. The proton gun which was developed satifies the requirements of spectroscopic plasma experiments and makes it possible to excite a plasma of inert gases under atmospheric pressure over a length of up to 100 cm, with the plasma having high homogeneity and stability. They obtained first results of spectroscopic measurements of the electron concentration of a helium plasma and the results agree with the theoretical predictions

A model for the operation of helium-filled proportional counter at low temperatures near 4.2 K

International Nuclear Information System (INIS)

Masaoka, Sei; Katano, Rintaro; Kishimoto, Shunji; Isozumi, Yasuhito

2000-01-01

In order to understand the operation of helium-filled proportional counter (HFPC) from the standpoint of fundamental atomic and molecular processes, we have surveyed previous works on collision processes in discharged helium gas. By analyzing gas gain curve, after-pulses and discharge current experimentally observed at 4.2 K, the electron avalanche and the secondary electron emission from cathode have been related to the collision processes in helium. A simplified model for the HFPC operation at low temperatures near 4.2 K has been constructed with the related processes

Heat transfer and thermal stress analysis in fluid-structure coupled field

International Nuclear Information System (INIS)

Li, Ming-Jian; Pan, Jun-Hua; Ni, Ming-Jiu; Zhang, Nian-Mei

2015-01-01

In this work, three-dimensional simulation on conjugate heat transfer in a fluid-structure coupled field was carried out. The structure considered is from the dual-coolant lithium-lead (DCLL) blanket, which is the key technology of International Thermo-nuclear Experimental Reactor (ITER). The model was developed based on finite element-finite volume method and was employed to investigate mechanical behaviours of Flow Channel Insert (FCI) and heat transfer in the blanket under nuclear reaction. Temperature distribution, thermal deformation and thermal stresses were calculated in this work, and the effects of thermal conductivity, convection heat transfer coefficient and flow velocity were analyzed. Results show that temperature gradients and thermal stresses of FCI decrease when FCI has better heat conductivity. Higher convection heat transfer coefficient will result in lower temperature, thermal deformations and stresses in FCI. Analysis in this work could be a theoretical basis of blanket optimization. - Highlights: • We use FVM and FEM to investigate FCI structural safety considering heat transfer and FSI effects. • Higher convective heat transfer coefficient is beneficial for the FCI structural safety without much affect to bulk flow temperature. • Smaller FCI thermal conductivity can better prevent heat leakage into helium, yet will increase FCI temperature gradient and thermal stress. • Three-dimensional simulation on conjugate heat transfer in a fluid-structure coupled field was carried out

A Generalised Assessment of Working Fluids and Radial Turbines for Non-Recuperated Subcritical Organic Rankine Cycles

Directory of Open Access Journals (Sweden)

Martin T. White

2018-03-01

Full Text Available The aim of this paper is to conduct a generalised assessment of both optimal working fluids and radial turbine designs for small-scale organic Rankine cycle (ORC systems across a range of heat-source temperatures. The former has been achieved by coupling a thermodynamic model of subcritical, non-recperated cycles with the Peng–Robinson equation of state, and optimising the working-fluid and cycle parameters for heat-source temperatures ranging between 80 ° C and 360 ° C . The critical temperature of the working fluid is found to be an important parameter governing working-fluid selection. Moreover, a linear correlation between heat-source temperature and the optimal critical temperature that achieves maximum power output has been found for heat-source temperatures below 300 ° C ( T cr = 0.830 T hi + 41.27 . This correlation has been validated against cycle calculations completed for nine predefined working fluids using both the Peng–Robinson equation of state and using the REFPROP program. Ultimately, this simple correlation can be used to identify working-fluid candidates for a specific heat-source temperature. In the second half of this paper, the effect of the heat-source temperature on the optimal design of a radial-inflow turbine rotor for a 25 kW subcritical ORC system has been studied. As the heat-source temperature increases, the optimal blade-loading coefficient increases, whilst the optimal flow coefficient reduces. Furthermore, passage losses are dominant in turbines intended for low-temperature applications. However, at higher heat-source temperatures, clearance losses become more dominant owing to the reduced blade heights. This information can be used to identify the most direct route to efficiency improvements in these machines. Finally, it is observed that the transition from a conventional converging stator to a converging-diverging stator occurs at heat-source temperatures of approximately 165 ° C , whilst radially

Manufacturing cycle for pure neon-helium mixture production

International Nuclear Information System (INIS)

Batrakov, B.P.; Kravchenko, V.A.

1980-01-01

The manufacturing cycle for pure neon-helium mixture production with JA-300 nitrogen air distributing device has been developed. Gas mixture containing 2-3% of neon-helium mixture (the rest is mainly nitrogen 96-97%) is selected out of the cover of the JA-300 column condensator and enters the deflegmator under the 2.3-2.5 atm. pressure. The diflegmator presents a heat exchange apparatus in which at 78 K liquid nitrogen the condensation of nitrogen from the mixture of gases entering from the JA-300 column takes place. The enriched gas mixture containing 65-70% of neon-helium mixture and 30-35% of nitrogen goes out from the deflegmator. This enriched neon-helium mixture enters the gasgoeder for impure (65-70%) neon-helium mixture. Full cleaning of-neon helium mixture of nitrogen is performed by means of an adsorber. As adsorbent an activated coal has been used. Adsorption occurs at the 78 K temperature of liquid nitrogen and pressure P=0.1 atm. As activated coal cooled down to nitrogen temperature adsorbs nitrogen better than neon and helium, the nitrogen from the mixture is completely adsorbed. Pure neon-helium mixture from the adsorber comes into a separate gasgolder. In one campaign the cycle allows obtaining 2 m 3 of the mixture. The mixture contains 0.14% of nitrogen, 0.01% of oxygen and 0.06% of hydrogen

Automated recognition of helium speech. Phase I: Investigation of microprocessor based analysis/synthesis system

Science.gov (United States)

Jelinek, H. J.

1986-01-01

This is the Final Report of Electronic Design Associates on its Phase I SBIR project. The purpose of this project is to develop a method for correcting helium speech, as experienced in diver-surface communication. The goal of the Phase I study was to design, prototype, and evaluate a real time helium speech corrector system based upon digital signal processing techniques. The general approach was to develop hardware (an IBM PC board) to digitize helium speech and software (a LAMBDA computer based simulation) to translate the speech. As planned in the study proposal, this initial prototype may now be used to assess expected performance from a self contained real time system which uses an identical algorithm. The Final Report details the work carried out to produce the prototype system. Four major project tasks were: a signal processing scheme for converting helium speech to normal sounding speech was generated. The signal processing scheme was simulated on a general purpose (LAMDA) computer. Actual helium speech was supplied to the simulation and the converted speech was generated. An IBM-PC based 14 bit data Input/Output board was designed and built. A bibliography of references on speech processing was generated.

Solubility of helium in mercury for bubbling technology of the spallation neutron mercury target

International Nuclear Information System (INIS)

Hasegawa, S.; Naoe, T.; Futakawa, M.

2010-01-01

The pitting damage of mercury target container that originates in the pressure wave excited by the proton beam incidence becomes a large problem to reach the high-power neutron source in JSNS and SNS. The lifetime of mercury container is decreased remarkably by the pitting damage. As one of solutions, the pressure wave is mitigated by injecting the helium micro bubbles in mercury. In order to inject the helium micro bubbles into mercury, it is important to understand the characteristic of micro bubbles in mercury. The solubility of mercury-helium system is a key factor to decide bubbling conditions, because the disappearance behavior, i.e. the lifetime of micro bubbles, depends on the solubility. In addition, the bubble generation method is affected by it. Moreover, the experimental data related to the solubility of helium in mercury hardly exist. In this work, the solubility was obtained experimentally by measuring precisely the pressure drop of the gas that is facing to mercury surface. The pressure drop was attributed to the helium dissolution into mercury. Based on the measured solubility, the lifetime of micro bubbles and the method of the bubble generation is estimated using the solubility data.

Transfer effects after working memory training lead to improved fluid intelligence

OpenAIRE

Onken, Johanna

2013-01-01

Fluid intelligence describes the ability to think abstract, to adapt to new situations and to solve unknown problems. It is important for learning as well as for academic and professional success. Working memory is characterized as a cognitive system, that saves information over a short period of time in spite of possible distractions. More- over, working memory is able to assess the relevance of information while requirements change. Effective implicit training is able to increase the workin...

First-principles calculations of helium and neon desorption from cavities in silicon

International Nuclear Information System (INIS)

Eddin, A Charaf; Pizzagalli, L

2012-01-01

Combining density functional theory, the nudged elastic band technique, and the ultradense fluid model, we investigated the desorption process of He and Ne in silicon. Our results show that the internal surfaces of gas-filled bubbles are not a limiting factor during desorption experiments, since the surface reconstruction opens diffusion paths easier than in the bulk. We show that the vibrational contribution to the energy of helium in the bulk has to be considered in order to determine realistic pressures in the bubbles, when comparing experiments and simulations. At the maximum of desorption, an average pressure of 1-2 GPa is computed. (paper)

Standard Guide for Simulation of Helium Effects in Irradiated Metals

CERN Document Server

American Society for Testing and Materials. Philadelphia

1996-01-01

1.1 This guide provides advice for conducting experiments to investigate the effects of helium on the properties of metals where the technique for introducing the helium differs in some way from the actual mechanism of introduction of helium in service. Simulation techniques considered for introducing helium shall include charged particle implantation, exposure to α-emitting radioisotopes, and tritium decay techniques. Procedures for the analysis of helium content and helium distribution within the specimen are also recommended. 1.2 Two other methods for introducing helium into irradiated materials are not covered in this guide. They are the enhancement of helium production in nickel-bearing alloys by spectral tailoring in mixed-spectrum fission reactors, and isotopic tailoring in both fast and mixed-spectrum fission reactors. These techniques are described in Refs (1-5). Dual ion beam techniques (6) for simultaneously implanting helium and generating displacement damage are also not included here. This lat...

Helium-induced weld degradation of HT-9 steel

International Nuclear Information System (INIS)

Wang, Chin-An; Chin, B.A.; Lin, Hua T.; Grossbeck, M.L.

1992-01-01

Helium-bearing Sandvik HT-9 ferritic steel was tested for weldability to simulate the welding of structural components of a fusion reactor after irradiation. Helium was introduced into HT-9 steel to 0.3 and 1 atomic parts per million (appm) by tritium doping and decay. Autogenous single pass full penetration welds were produced using the gas tungsten arc (GTA) welding process under laterally constrained conditions. Macroscopic examination showed no sign of any weld defect in HT-9 steel containing 0.3 appm helium. However, intergranular micro cracks were observed in the HAZ of HT-9 steel containing 1 appm helium. The microcracking was attributed to helium bubble growth at grain boundaries under the influence of high stresses and temperatures that were present during welding. Mechanical test results showed that both yield strength (YS) and ultimate tensile strength (UTS) decreased with increasing temperature, while the total elongation increased with increasing temperature for all control and helium-bearing HT-9 steels

Genetic changes in Mammalian cells transformed by helium cells

Energy Technology Data Exchange (ETDEWEB)

Durante, M.; Grossi, G. (Naples Univ. (Italy). Dipt. di Scienze Fisiche); Yang, T.C.; Roots, R. (Lawrence Berkeley Lab., CA (USA))

1990-11-01

Midterm Syrian Hamster embryo (SHE) cells were employed to study high LET-radiation induced tumorigenesis. Normal SHE cells (secondary passage) were irradiated with accelerated helium ions at an incident energy of 22 MeV/u (9--10 keV/{mu}m). Transformed clones were isolated after growth in soft agar of cells obtained from the foci of the initial monolayer plated postirradiation. To study the progression process of malignant transformation, the transformed clones were followed by monolayer subculturing for prolonged periods of time. Subsequently, neoplasia tests in nude mice were done. In this work, however, we have focused on karyotypic changes in the banding patterns of the chromosomes during the early part of the progressive process of cell transformation for helium ion-induced transformed cells. 26 refs., 5 figs., 2 tabs.

Charged condensate and helium dwarf stars

Energy Technology Data Exchange (ETDEWEB)

Gabadadze, Gregory; Rosen, Rachel A, E-mail: gg32@nyu.edu, E-mail: rar339@nyu.edu [Center for Cosmology and Particle Physics, Department of Physics, New York University, New York, NY 10003 (United States)

2008-10-15

White dwarf stars composed of carbon, oxygen and heavier elements are expected to crystallize as they cool down below certain temperatures. Yet, simple arguments suggest that the helium white dwarf cores may not solidify, mostly because of zero-point oscillations of the helium ions that would dissolve the crystalline structure. We argue that the interior of the helium dwarfs may instead form a macroscopic quantum state in which the charged helium-4 nuclei are in a Bose-Einstein condensate, while the relativistic electrons form a neutralizing degenerate Fermi liquid. We discuss the electric charge screening, and the spectrum of this substance, showing that the bosonic long-wavelength fluctuations exhibit a mass gap. Hence, there is a suppression at low temperatures of the boson contribution to the specific heat-the latter being dominated by the specific heat of the electrons near the Fermi surface. This state of matter may have observational signatures.

On the helium gas leak test

International Nuclear Information System (INIS)

Nishikawa, Akira; Ozaki, Susumu

1975-01-01

The helium gas leak test (Helium mass spectrometer testing) has a leak detection capacity of the highest level in practical leak tests and is going to be widely applied to high pressure vessels, atomic and vacuum equipments that require high tightness. To establish a standard test procedure several series of experiments were conducted and the results were investigated. The conclusions are summarized as follows: (1) The hood method is quantitatively the most reliable method. The leak rate obtained by tests using 100% helium concentration should be the basis of the other method of test. (2) The integrating method, bell jar method, and vacuum spray method can be considered quantitative when particular conditions are satisfied. (3) The sniffer method is not to be considered quantitive. (4) The leak rate of the hood, integrating, and bell jar methods is approximately proportional to the square of the helium partial pressure. (auth.)

Helium accumulation and bubble formation in FeCoNiCr alloy under high fluence He+ implantation

Science.gov (United States)

Chen, Da; Tong, Y.; Li, H.; Wang, J.; Zhao, Y. L.; Hu, Alice; Kai, J. J.

2018-04-01

Face-centered cubic (FCC) high-entropy alloys (HEA), as emerging alloys with equal-molar or near equal-molar constituents, show a promising radiation damage resistance under heavy ion bombardment, making them potential for structural material application in next-generation nuclear reactors, but the accumulation of light helium ions, a product of nuclear fission reaction, has not been studied. The present work experimentally studied the helium accumulation and bubble formation at implantation temperatures of 523 K, 573 K and 673 K in a homogenized FCC FeCoNiCr HEA, a HEA showing excellent radiation damage resistance under heavy ion irradiation. The size and population density of helium bubbles in FeCoNiCr samples were quantitatively analyzed through transmission electron microscopy (TEM), and the helium content existing in bubbles were estimated from a high-pressure Equation of State (EOS). We found that the helium diffusion in such condition was dominated by the self-interstitial/He replacement mechanism, and the corresponding activation energy in FeCoNiCr is comparable with the vacancy migration energy in Ni and austenitic stainless steel but only 14.3%, 31.4% and 51.4% of the accumulated helium precipitated into helium bubbles at 523 K, 573 K and 673 K, respectively, smaller than the pure Ni case. Importantly, the small bubble size suggested that FeCoNiCr HEA has a high resistance of helium bubble formation compared with Ni and steels.

A general framework to select working fluid and configuration of ORCs for low-to-medium temperature heat sources

International Nuclear Information System (INIS)

Vivian, Jacopo; Manente, Giovanni; Lazzaretto, Andrea

2015-01-01

Highlights: • General guidelines are proposed to select ORC working fluid and cycle layout. • Distance between critical and heat source temperature for optimal fluid selection. • Separate contributions of cycle efficiency and heat recovery factor. - Abstract: The selection of the most suitable working fluid and cycle configuration for a given heat source is a fundamental step in the search for the optimum design of Organic Rankine Cycles. In this phase cycle efficiency and heat source recovery factor lead to opposite design choices in the achievement of maximum system efficiency and, in turn, maximum power output. In this work, both separate and combined effects of these two performance factors are considered to supply a thorough understanding of the compromise resulting in maximum performance. This goal is pursued by carrying out design optimizations of four different ORC configurations operating with twenty-seven working fluids and recovering heat from sensible heat sources in the temperature range 120–180 °C. Optimum working fluids and thermodynamic parameters are those which simultaneously allow high cycle efficiency and high heat recovery from the heat source to be obtained. General guidelines are suggested to reach this target for any system configuration. The distance between fluid critical temperature and inlet temperature of the heat source is found to play a key role in predicting the optimum performance of all system configurations regardless of the inlet temperature of the heat source

Helium-3 and helium-4 acceleration by high power laser pulses for hadron therapy

Directory of Open Access Journals (Sweden)

S. S. Bulanov

2015-06-01

Full Text Available The laser driven acceleration of ions is considered a promising candidate for an ion source for hadron therapy of oncological diseases. Though proton and carbon ion sources are conventionally used for therapy, other light ions can also be utilized. Whereas carbon ions require 400 MeV per nucleon to reach the same penetration depth as 250 MeV protons, helium ions require only 250 MeV per nucleon, which is the lowest energy per nucleon among the light ions (heavier than protons. This fact along with the larger biological damage to cancer cells achieved by helium ions, than that by protons, makes this species an interesting candidate for the laser driven ion source. Two mechanisms (magnetic vortex acceleration and hole-boring radiation pressure acceleration of PW-class laser driven ion acceleration from liquid and gaseous helium targets are studied with the goal of producing 250 MeV per nucleon helium ion beams that meet the hadron therapy requirements. We show that He^{3} ions, having almost the same penetration depth as He^{4} with the same energy per nucleon, require less laser power to be accelerated to the required energy for the hadron therapy.

Superfluid helium at subcritical active core

International Nuclear Information System (INIS)

Vasil'ev, V.V.; Lopatkin, A.V.; Muratov, V.G.; Rakhno, I.L.

2002-01-01

Power range and neutron flux wherein super thermal source was realized at high volume of superfluid helium were investigated. MCU, BRAND, MCNP codes were used for the calculation of reactors. It is shown that the availability of full-size diameter for cryogenic source of ultracold neutrons, as the source with superfluid helium is considered, is possible in the reflector of subcritical assembly. Results obtained from the MCNP-4B code application demonstrated that the density of thermal neutron flux in helium must be not higher than 2.3 x 10 11 s -1 cm -2 [ru

Helium leak testing methods in nuclear applications

International Nuclear Information System (INIS)

Ahmad, Anis

2004-01-01

Helium mass-spectrometer leak test is the most sensitive leak test method. It gives very reliable and sensitive test results. In last few years application of helium leak testing has gained more importance due to increased public awareness of safety and environment pollution caused by number of growing chemical and other such industries. Helium leak testing is carried out and specified in most of the critical area applications like nuclear, space, chemical and petrochemical industries

Pressurized-helium breakdown at very low temperatures

Energy Technology Data Exchange (ETDEWEB)

Metas, R J

1972-06-01

An investigation of the electrical-breakdown behavior of helium at very low temperatures has been carried out to assist the design and development of superconducting power cables. At very high densities, both liquid and gaseous helium showed an enhancement in electric strength when pressurized to a few atmospheres; conditioned values of breakdown fields then varied between 30 and 45 MV/m. Breakdown processes occurring over a wide range of helium densities are discussed. 24 references.

Dipole moments of molecules solvated in helium nanodroplets

International Nuclear Information System (INIS)

Stiles, Paul L.; Nauta, Klaas; Miller, Roger E.

2003-01-01

Stark spectra are reported for hydrogen cyanide and cyanoacetylene solvated in helium nanodroplets. The goal of this study is to understand the influence of the helium solvent on measurements of the permanent electric dipole moment of a molecule. We find that the dipole moments of the helium solvated molecules, calculated assuming the electric field is the same as in vacuum, are slightly smaller than the well-known gas-phase dipole moments of HCN and HCCCN. A simple elliptical cavity model quantitatively accounts for this difference, which arises from the dipole-induced polarization of the helium

Effect of Working Fluids on the Thermal Performance of a Bi-directional Solar Thermodiode

International Nuclear Information System (INIS)

Ko, Yung Joo

2008-02-01

(Smart Module System) were made. Six kinds of working fluids were used to investigate their effects on the thermal performance of a bi-directional solar thermo diode. Two kinds of thermo diodes were studied. The first one is the mono-directional thermo diode that allows heat flow in the desired direction but blocks in the opposite direction. The second one is the bi-directional thermo diode of which the direction of heat flow, surface absorptivity and heat capacity of the module can be adjusted for maximum energy efficiency. This hi-directional can be used both for the summer cooling and winter heating of buildings and shelters. Usually, the thermo diodes are simple beam shape, but in this study, they were redesigned a s two L-shaped loops mounted between a collector plate and a Storage tank. Rotable joints between the horizontal and inclined segments of the loop enable easy alteration of geat transfer direction. The loops and tank were filled with a working fluid for effective heat transfer when the solar thermo diode was forwarded biased. The solar thermo diode was heated by a radiant heater that consisted of 20 halogen lamps that generates a heat flux of about 1000W/m 2 on the collector surface. The working fluids used in the study were water, acetone, ethylalcohol. In addition, three kinds of silicon oil with different viscosity were studied. And three mixtures of water and ethylalcohol of different volume ratio were used. Finally, the nano fluids were also studied. Working fluids were tested with thermal conductivity values ranging from 0.1 to 0.56 W/m- .deg. C, thermal expansion coefficient values ranging from 1.8 x 10 -4 to 1.3 x 10 -3 K -1 , and kinematic viscosity values ranging from 0.65 x 10 -6 to 100 x 10 -6 m 2 /s. Through the study, it was found that the circulation point(CP) at the onset of fluid flow is very important. for a given working fluid, the heat transfer and heated stability of the system depends strongly on the circulation point of the fluid

Choice of optimal working fluid for binary power plants at extremely low temperature brine

Science.gov (United States)

Tomarov, G. V.; Shipkov, A. A.; Sorokina, E. V.

2016-12-01

The geothermal energy development problems based on using binary power plants utilizing lowpotential geothermal resources are considered. It is shown that one of the possible ways of increasing the efficiency of heat utilization of geothermal brine in a wide temperature range is the use of multistage power systems with series-connected binary power plants based on incremental primary energy conversion. Some practically significant results of design-analytical investigations of physicochemical properties of various organic substances and their influence on the main parameters of the flowsheet and the technical and operational characteristics of heat-mechanical and heat-exchange equipment for binary power plant operating on extremely-low temperature geothermal brine (70°C) are presented. The calculation results of geothermal brine specific flow rate, capacity (net), and other operation characteristics of binary power plants with the capacity of 2.5 MW at using various organic substances are a practical interest. It is shown that the working fluid selection significantly influences on the parameters of the flowsheet and the operational characteristics of the binary power plant, and the problem of selection of working fluid is in the search for compromise based on the priorities in the field of efficiency, safety, and ecology criteria of a binary power plant. It is proposed in the investigations on the working fluid selection of the binary plant to use the plotting method of multiaxis complex diagrams of relative parameters and characteristic of binary power plants. Some examples of plotting and analyzing these diagrams intended to choose the working fluid provided that the efficiency of geothermal brine is taken as main priority.

Helium atoms and molecules in strong magnetic fields

Science.gov (United States)

Mori, K.

Recent theoretical studies have shown that the neutron star surface may be composed of helium or heavier elements as hydrogen may be quickly depleted by diffuse nuclear burning Chang Bildsten However while Hydrogen atmospheres have been studied in great details atomic data for helium is available only for He ion Pavlov Bezchastnov 2005 We performed Hartree-Fock type calculation for Helium atom and molecules and computed their binding ionization and dissociation energies in strong magnetic fields B sim10 12 -- 10 15 G We will present ionization balance of Helium atmospheres at typical magnetic field strengths and temperatures to radio-quiet neutron stars and AXPs We will also discuss several implications of helium atmosphere to X-ray data of isolated neutron stars focusing on the detected spectral features

Tritium and helium-3 in metals

International Nuclear Information System (INIS)

Lasser, R.

1989-01-01

The book surveys recent results on the behaviour of tritium and its decay product helium-3 metals. In contrast to many earlier books which discuss the properties of the stable hydrogen isotopes without mentioning tritium, this book reviews mainly the results on tritium in metals. Due to the difficulties in preparing metal tritide samples, very important quantities such as diffusivity, superconductivity, solubility, etc. have only been determined very recently. The book not only presents the measured tritium data, but also the isotopic dependency of the different physical properties by comparing H, D and T results. A chapter is devoted to helium-3 in metals. Aspects such as helium release, generation of helium bubbles, swelling, and change of the lattice parameter upon aging are discussed. The book provides the reader with up-to-date information and deep insight into the behaviour of H, D, T and He-3 in metals. Further important topics such a tritium production, its risks, handling and discharge to the environment are also addressed

Helium cosmic ray flux measurements at Mars

International Nuclear Information System (INIS)

Lee, Kerry; Pinsky, Lawrence; Andersen, Vic; Zeitlin, Cary; Cleghorn, Tim; Cucinotta, Frank; Saganti, Premkumar; Atwell, William; Turner, Ron

2006-01-01

The helium energy spectrum in Martian orbit has been observed by the MARIE charged particle spectrometer aboard the 2001 Mars Odyssey spacecraft. The orbital data were taken from March 13, 2002 to October 28, 2003, at which time a very intense Solar Particle Event caused a loss of communication between the instrument and the spacecraft. The silicon detector stack in MARIE is optimized for the detection of protons and helium in the energy range below 100MeV/n, which typically includes almost all of the flux during SPEs. This also makes MARIE an efficient detector for GCR helium in the energy range of 50-150MeV/n. We will present the first fully normalized flux results from MARIE, using helium ions in this energy range

Helium cosmic ray flux measurements at Mars

Energy Technology Data Exchange (ETDEWEB)

Lee, Kerry [University of Houston, 4800 Calhoun Rd. Houston, TX 77204 (United States)]. E-mail: ktlee@ems.jsc.nasa.gov; Pinsky, Lawrence [University of Houston, 4800 Calhoun Rd. Houston, TX 77204 (United States); Andersen, Vic [University of Houston, 4800 Calhoun Rd. Houston, TX 77204 (United States); Zeitlin, Cary [National Space Biomedical Research Institute, Baylor College of Medicine, Houston, TX (United States); Cleghorn, Tim [NASA Johnson Space Center, 2101 NASA Road 1, Houston, TX 77058 (United States); Cucinotta, Frank [NASA Johnson Space Center, 2101 NASA Road 1, Houston, TX 77058 (United States); Saganti, Premkumar [Prairie View A and M University, P.O. Box 519, Prairie View, TX 77446-0519 (United States); Atwell, William [The Boeing Company, Houston, TX (United States); Turner, Ron [Advancing National Strategies and Enabling Results (ANSER), Arlington, Virginia (United States)

2006-10-15

The helium energy spectrum in Martian orbit has been observed by the MARIE charged particle spectrometer aboard the 2001 Mars Odyssey spacecraft. The orbital data were taken from March 13, 2002 to October 28, 2003, at which time a very intense Solar Particle Event caused a loss of communication between the instrument and the spacecraft. The silicon detector stack in MARIE is optimized for the detection of protons and helium in the energy range below 100MeV/n, which typically includes almost all of the flux during SPEs. This also makes MARIE an efficient detector for GCR helium in the energy range of 50-150MeV/n. We will present the first fully normalized flux results from MARIE, using helium ions in this energy range.

Design and Experiment of Auxiliary Bearing for Helium Blower of HTR-PM

International Nuclear Information System (INIS)

Yang Guojun; Shi Zhengang; Liu Xingnan; Zhao Jingjing

2014-01-01

The helium blower is the important equipment for HTR-PM. Active magnetic bearing (AMB) instead of mechanical bearing is selected to support the rotor of the helium blower. However, one implication of AMB is the requirement to provide the auxiliary bearing to mitigate the effects of failures or overload conditions. The auxiliary bearing is used to support the rotor when the AMB fails to work. It must support the dropping rotor and bear the great impact force and friction heat. The design of the auxiliary bearing is one of the challenging problems in the whole system. It is very important for the helium blower with AMB of HTR-PM to make success. The rotor’s length of helium blower of HTR-PM is about 3.3 m, its weight is about 4000 kg and the rotating speed is 4000 r/min. The axial load is 4500kg, and the radial load is 1950kg. The angular contact ball bearing was selected as the auxiliary bearing. The test rig has been finished. It is difficult to analyze the falling course of the rotor. The preliminary analysis of the dropping rotor was done in the special condition. The impact force of auxiliary bearing was computed for the axial and radial load. And the dropping test of the blower rotor for HTR-10 will be introduced also in this paper. Results offer the important theoretical base for the protector design of the helium blower with AMB for HTR-PM. (author)

A Latent Variable Analysis of Working Memory Capacity, Short-Term Memory Capacity, Processing Speed, and General Fluid Intelligence.

Science.gov (United States)

Conway, Andrew R. A.; Cowan, Nelsin; Bunting, Michael F.; Therriault, David J.; Minkoff, Scott R. B.

2002-01-01

Studied the interrelationships among general fluid intelligence, short-term memory capacity, working memory capacity, and processing speed in 120 young adults and used structural equation modeling to determine the best predictor of general fluid intelligence. Results suggest that working memory capacity, but not short-term memory capacity or…

Atomistic simulation of helium bubble nucleation in palladium

Energy Technology Data Exchange (ETDEWEB)

Wang Liang [Department of Applied Physics, Hunan University, Changsha 410082 (China); Hu, Wangyu [Department of Applied Physics, Hunan University, Changsha 410082 (China)], E-mail: wangyuhu2001cn@yahoo.com.cn; Xiao Shifang [Department of Applied Physics, Hunan University, Changsha 410082 (China)], E-mail: sfxiao@yahoo.com.cn; Yang Jianyu [Department of Maths and Physics, Hunan Institute of Engineering, Xiangtan 411104 (China); Deng Huiqiu [Department of Applied Physics, Hunan University, Changsha 410082 (China)

2009-09-15

A palladium crystal has been constructed with 11808 atoms. 55 helium atoms occupied the octahedral position of palladium crystal are introduced and retained in a spherical region. Molecular dynamic simulations are performed in a constant temperature and constant volume ensemble (NVT) with temperature controlled by Nose-Hoover thermostat. The interactions between palladium atoms are described with modified analytic embedded atom method (MAEAM), the interactions between palladium atom and helium atom are in the form of Morse potential, and the interactions between helium atoms are in the form of L-J potential function. With the analysis of the radial distribution function (RDF) and microstructure, it reveals that some of helium atoms form a series of clusters with different size, and the nucleation core is random at low temperature, and which is the embryo of helium bubble. Increasing temperature can accelerate the process of bubble nucleation, and the clusters will aggregate and coalesce into a bigger one in which there are no palladium atoms, and it is considered as a helium bubble.

Low flux and low energy helium ion implantation into tungsten using a dedicated plasma source

Energy Technology Data Exchange (ETDEWEB)

Pentecoste, Lucile [GREMI, CNRS/Université d’Orléans, 14 rue d’Issoudun, B.P. 6744, 45067 Orléans Cedex2 (France); Thomann, Anne-Lise, E-mail: anne-lise.thomann@univ-orleans.fr [GREMI, CNRS/Université d’Orléans, 14 rue d’Issoudun, B.P. 6744, 45067 Orléans Cedex2 (France); Melhem, Amer; Caillard, Amael; Cuynet, Stéphane; Lecas, Thomas; Brault, Pascal [GREMI, CNRS/Université d’Orléans, 14 rue d’Issoudun, B.P. 6744, 45067 Orléans Cedex2 (France); Desgardin, Pierre; Barthe, Marie-France [CNRS, UPR3079 CEMHTI, 1D avenue de la Recherche Scientifique, 45071 Orléans Cedex2 (France)

2016-09-15

The aim of this work is to investigate the first stages of defect formation in tungsten (W) due to the accumulation of helium (He) atoms inside the crystal lattice. To reach the required implantation conditions, i.e. low He ion fluxes (10{sup 11}–10{sup 14} ions.cm{sup 2}.s{sup −1}) and kinetic energies below the W atom displacement threshold (about 500 eV for He{sup +}), an ICP source has been designed and connected to a diffusion chamber. Implantation conditions have been characterized by means of complementary diagnostics modified for measurements in this very low density helium plasma. It was shown that lowest ion fluxes could only be reached for the discharge working in capacitive mode either in α or γ regime. Special attention was paid to control the energy gained by the ions by acceleration through the sheath at the direct current biased substrate. At very low helium pressure, in α regime, a broad ion energy distribution function was evidenced, whereas a peak centered on the potential difference between the plasma and the biased substrate was found at higher pressures in the γ mode. Polycrystalline tungsten samples were exposed to the helium plasma in both regimes of the discharge and characterized by positron annihilation spectroscopy in order to detect the formed vacancy defects. It was found that W vacancies are able to be formed just by helium accumulation and that the same final implanted state is reached, whatever the operating mode of the capacitive discharge.

Recycling, inventory and permeation of hydrogen isotopes and helium in the first wall of a thermonuclear fusion reactor

International Nuclear Information System (INIS)

Gervasini, G.; Reiter, F.

1989-01-01

The work was divided into three parts. The first part, which is theoretical, examines the behaviour of hydrogen in metals. After an introduction on the presence of hydrogen isotopes in fusion reactors, the main phenomena connected with hydrogen-metal interaction are summarised: solubility, diffusivity and trapping in material defects. The metal temperature is highlighted as the main parameter in the description of the phenomena. The second part of the work, also theoretical, concerns the interaction between helium and metals. We have tried as much as possible to show analogies and differences in the comparisons of the behaviour of hydrogen. The main types of damage caused by helium in metallic structures, which are the most important consequence of helium-metal interaction, were summarised. The characteristics of helium were treated in greater depth than those of hydrogen, because the latter are very well known. Also, there is a vast literature on the hydrogen-metal interaction. In the third and last part of the work a model was identified which allows the simulation of the evolution of a system formed from a metal in which hydrogen and helium isotopes have been introduced. A system of algebraic-differential equations was used to study the temporal evolution of the concentrations, the recycling, the inventory and the permeation of tritium and helium considering that these atoms diffuse in the metallic lattice and remain trapped in the vacancies created inside the metal by the bombardment of the neutrons from the fusion reactions. For the numerical simulation a series of data intended to represent the situation inside a thermonuclear reactor as precisely as possible were used for the numerical simulation. Analysis of the system was preceded by the analytical resolution of the steady state equations so that they could be compared with the simulation results

Helium-Charged La-Ni-Al Thin Films Deposited by Magnetron Sputtering

International Nuclear Information System (INIS)

Shi Liqun; Chen Deming; Xu Shilin; Liu Chaozhu; Hao Wanli; Zhou Zhuyin

2005-01-01

An advanced implantation of low energy helium-4 atoms during the La-Ni-Al film growth by adopting magnetron sputtering with Ar/He mixture gases is discussed. Both proton backscattering spectroscopy (PBS) and elastic recoil detection (ERD) analyses were adopted to measure helium concentration of the films and distribution in the near-surface region. Helium atoms with a high concentration incorporate evenly in deposited film. The introduction of the helium with no extra irradiation damage is expected by choosing suitable deposition conditions. It was found that amorphous and crystalline LaNi 5 -type structures can be achieved when sputtered with pure Ar and Ar/He mixture gases at room temperature, respectively. Thermal desorption experiments proposes that a part of hydrogen atoms are bound to trapped helium at crystal and releases together with helium. Only a small fraction of helium is released from the helium-vacancy clusters in lower temperature range and most of helium is released from small size helium bubbles in the high temperature range

Evolution of helium stars: a self-consistent determination of the boundary of a helium burning convective core

International Nuclear Information System (INIS)

Savonije, G.J.; Takens, R.J.

1976-01-01

A generalization of the Henyey-scheme is given that introduces the mass of the convective core and the density at the outer edge of the convective core boundary as unknowns which have to be solved simultaneously with the other unknowns. As a result, this boundary is determined in a physically self-consistent way for expanding as well as contracting cores, i.e. during the Henyey iterative cycle; its position becomes consistent with the overall physical structure of the star, including the run of the chemical abundances throughout the star. Using this scheme, the evolution of helium stars was followed up to carbon ignition for a number of stellar masses. As compared with some earlier investigations, the calculations show a rather large increase in mass of the convective cores during core helium burning. Evolutionary calculations for a 2M(sun) helium star show that the critical mass for which a helium star ignites carbon non-degenerately lies near 2M(sun). (orig.) [de

Effects of helium implantation on fatigue properties of F82H-IEA heat

Energy Technology Data Exchange (ETDEWEB)

Yamamoto, N.; Murase, Y.; Nagakawa, J. [National Research Institute for Metals, Tsukuba, Ibaraki (Japan)

2007-07-01

Full text of publication follows: Ferritic steels including reduced activation ones that have been recognized as attractive structural candidates for DEMO reactors and the beyond are known to be highly resistant to helium embrittlement. However, almost studies that deduced this behavior have been carried out by means of short time experiments such as tensile tests, and a few results are available concerning long term inspections, although the detrimental helium effect appears more severely in the latter. The aim of this work is to obtain further information on the influence of helium on fatigue properties of a representative reduced activation ferritic/martensitic steel F82H (8Cr2WVTa) using helium implantation technique with a cyclotron. The material examined is an IEA heat version of F82H. In order to realize a fine grain size due to thin specimens (0.08 mm thick) for ion irradiation, normalizing was conducted at rather low temperature of 1213 K, followed by tempering at 1023 K. Helium was implanted by {alpha}-particle irradiation at 823 K, a desired highest temperature of this material for first wall application, to the concentration of 100 appm He with an implantation rate of about 1.7 x 10{sup -3} appm He/s. Subsequent fatigue tests were conducted at the same temperature as that of irradiation, not only on implanted specimens but also on reference controls which were not implanted with helium but experienced the same metallurgical histories as those of irradiated ones. After fracture, samples were observed with electron microscopes. In short time periods, it has been notified that helium introduction caused no significant deterioration of both fatigue life and extension at fracture. In addition, all specimens failed in a fully trans-crystalline and ductile manner, irrespective of whether helium was present or not. Indication of grain boundary embrittlement was therefore not discerned. These facts would reflect insusceptible characteristics of this material to

Effects of helium implantation on fatigue properties of F82H-IEA heat

International Nuclear Information System (INIS)

Yamamoto, N.; Murase, Y.; Nagakawa, J.

2007-01-01

Full text of publication follows: Ferritic steels including reduced activation ones that have been recognized as attractive structural candidates for DEMO reactors and the beyond are known to be highly resistant to helium embrittlement. However, almost studies that deduced this behavior have been carried out by means of short time experiments such as tensile tests, and a few results are available concerning long term inspections, although the detrimental helium effect appears more severely in the latter. The aim of this work is to obtain further information on the influence of helium on fatigue properties of a representative reduced activation ferritic/martensitic steel F82H (8Cr2WVTa) using helium implantation technique with a cyclotron. The material examined is an IEA heat version of F82H. In order to realize a fine grain size due to thin specimens (0.08 mm thick) for ion irradiation, normalizing was conducted at rather low temperature of 1213 K, followed by tempering at 1023 K. Helium was implanted by α-particle irradiation at 823 K, a desired highest temperature of this material for first wall application, to the concentration of 100 appm He with an implantation rate of about 1.7 x 10 -3 appm He/s. Subsequent fatigue tests were conducted at the same temperature as that of irradiation, not only on implanted specimens but also on reference controls which were not implanted with helium but experienced the same metallurgical histories as those of irradiated ones. After fracture, samples were observed with electron microscopes. In short time periods, it has been notified that helium introduction caused no significant deterioration of both fatigue life and extension at fracture. In addition, all specimens failed in a fully trans-crystalline and ductile manner, irrespective of whether helium was present or not. Indication of grain boundary embrittlement was therefore not discerned. These facts would reflect insusceptible characteristics of this material to high

A potential spatial working memory training task to improve both episodic memory and fluid intelligence.

Directory of Open Access Journals (Sweden)

Sarah R Rudebeck

Full Text Available One current challenge in cognitive training is to create a training regime that benefits multiple cognitive domains, including episodic memory, without relying on a large battery of tasks, which can be time-consuming and difficult to learn. By giving careful consideration to the neural correlates underlying episodic and working memory, we devised a computerized working memory training task in which neurologically healthy participants were required to monitor and detect repetitions in two streams of spatial information (spatial location and scene identity presented simultaneously (i.e. a dual n-back paradigm. Participants' episodic memory abilities were assessed before and after training using two object and scene recognition memory tasks incorporating memory confidence judgments. Furthermore, to determine the generalizability of the effects of training, we also assessed fluid intelligence using a matrix reasoning task. By examining the difference between pre- and post-training performance (i.e. gain scores, we found that the trainers, compared to non-trainers, exhibited a significant improvement in fluid intelligence after 20 days. Interestingly, pre-training fluid intelligence performance, but not training task improvement, was a significant predictor of post-training fluid intelligence improvement, with lower pre-training fluid intelligence associated with greater post-training gain. Crucially, trainers who improved the most on the training task also showed an improvement in recognition memory as captured by d-prime scores and estimates of recollection and familiarity memory. Training task improvement was a significant predictor of gains in recognition and familiarity memory performance, with greater training improvement leading to more marked gains. In contrast, lower pre-training recollection memory scores, and not training task improvement, led to greater recollection memory performance after training. Our findings demonstrate that practice

DIRECT EVALUATION OF THE HELIUM ABUNDANCES IN OMEGA CENTAURI

Energy Technology Data Exchange (ETDEWEB)

Dupree, A. K.; Avrett, E. H., E-mail: dupree@cfa.harvard.edu, E-mail: eavrett@cfa.harvard.edu [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)

2013-08-20

A direct measure of the helium abundances from the near-infrared transition of He I at 1.08 {mu}m is obtained for two nearly identical red giant stars in the globular cluster Omega Centauri. One star exhibits the He I line; the line is weak or absent in the other star. Detailed non-local thermal equilibrium semi-empirical models including expansion in spherical geometry are developed to match the chromospheric H{alpha}, H{beta}, and Ca II K lines, in order to predict the helium profile and derive a helium abundance. The red giant spectra suggest a helium abundance of Y {<=} 0.22 (LEID 54064) and Y = 0.39-0.44 (LEID 54084) corresponding to a difference in the abundance {Delta}Y {>=} 0.17. Helium is enhanced in the giant star (LEID 54084) that also contains enhanced aluminum and magnesium. This direct evaluation of the helium abundances gives observational support to the theoretical conjecture that multiple populations harbor enhanced helium in addition to light elements that are products of high-temperature hydrogen burning. We demonstrate that the 1.08 {mu}m He I line can yield a helium abundance in cool stars when constraints on the semi-empirical chromospheric model are provided by other spectroscopic features.

Capacity enhancement of indigenous expansion engine based helium liquefier

Science.gov (United States)

Doohan, R. S.; Kush, P. K.; Maheshwari, G.

2017-02-01

Development of technology and understanding for large capacity helium refrigeration and liquefaction at helium temperature is indispensable for coming-up projects. A new version of helium liquefier designed and built to provide approximately 35 liters of liquid helium per hour. The refrigeration capacity of this reciprocating type expansion engine machine has been increased from its predecessor version with continuous improvement and deficiency debugging. The helium liquefier has been built using components by local industries including cryogenic Aluminum plate fin heat exchangers. Two compressors with nearly identical capacity have been deployed for the operation of system. Together they consume about 110 kW of electric power. The system employs liquid Nitrogen precooling to enhance liquid Helium yield. This paper describes details of the cryogenic expander design improvements, reconfiguration of heat exchangers, performance simulation and their experimental validation.

Novel and conventional working fluid mixtures for solar Rankine cycles: Performance assessment and multi-criteria selection

International Nuclear Information System (INIS)

Mavrou, Paschalia; Papadopoulos, Athanasios I.; Stijepovic, Mirko Z.; Seferlis, Panos; Linke, Patrick; Voutetakis, Spyros

2015-01-01

This work investigates the performance of working fluid mixtures for use in solar ORC (Organic Rankine Cycle systems) with heat storage employing FPC (Flat Plate Collectors). Several mixtures are considered including conventional choices often utilized in ORC as well as novel mixtures previously designed using advanced computer aided molecular design methods (Papadopoulos et al., 2013). The impact of heat source variability on the ORC performance is assessed for different working fluid mixtures. Solar radiation is represented in detail through actual, hourly averaged data for an entire year. A multi-criteria mixture selection methodology unveils important trade-offs among several important system operating parameters and efficiently highlights optimum operating ranges. Such parameters include the ORC thermal efficiency, the net generated power, the volume ratio across the turbine, the mass flow rate of the ORC working fluid, the evaporator temperature glide, the temperature drop in the storage tank, the ORC total yearly operating duration, the required collector aperture area to generate 1 kW of power and the irreversibility. A mixture of neopentane – 2-fluoromethoxy-2-methylpropane at 70% neopentane is found to be the most efficient in all the considered criteria simultaneously. - Highlights: • Investigation of novel and conventional working fluid mixtures for solar ORCs. • Systematic, multi-criteria assessment methodology for mixture selection. • Simultaneous consideration of multiple important mixture performance criteria. • Effects of year-round solar variability in a solar ORC with heat storage tank

Liquid-helium scintillation detection with germanium photodiodes

International Nuclear Information System (INIS)

Luke, P.N.; Haller, E.E.; Steiner, H.M.

1982-05-01

Special high-purity germanium photodiodes have been developed for the direct detection of vacuum ultraviolet scintillations in liquid helium. The photodiodes are immersed in the liquid helium, and scintillations are detected through one of the bare sides of the photodiodes. Test results with scintillation photons produced by 5.3-MeV α particles are presented. The use of these photodiodes as liquid-helium scintillation detectors may offer substantial improvements over the alternate detection method requiring the use of wavelength shifters and photomultiplier tubes

Helium release from metals with face-centered cubic structure

International Nuclear Information System (INIS)

Sciani, V.; Lucki, G.; Jung, P.

1984-01-01

The helium release from gold sheets of 5 and 54 μm of thickness and helium concentrations from 10 -9 to 10 -5 ap of He during the isothermal and linear annealing is studied. The helium was put in the sample through the implantation of alpha particles, with variable energy,in the cyclotron. The free diffusion of the atoms of the helium, where the diffusion coefficient follows an Arrhenius law is studied. (E.G.) [pt

Helium leak testing of scanning electron microscope

International Nuclear Information System (INIS)

Ahmad, Anis; Tripathi, S.K.; Mukherjee, D.

2015-01-01

Scanning Electron Microscope (SEM) is a specialized electron-optical device which is used for imaging of miniscule features on topography of material specimens. Conventional SEMs used finely focused high energy (about 30 KeV) electron beam probes of diameter of about 10nm for imaging of solid conducting specimens. Vacuum of the order of 10"-"5 Torr is prerequisite for conventional Tungsten filament type SEMs. One such SEM was received from one of our laboratory in BARC with a major leak owing to persisting poor vacuum condition despite continuous pumping for several hours. He-Leak Detection of the SEM was carried out at AFD using vacuum spray Technique and various potential leak joints numbering more than fifty were helium leak tested. The major leak was detected in the TMP damper bellow. The part was later replaced and the repeat helium leak testing of the system was carried out using vacuum spray technique. The vacuum in SEM is achieved is better than 10"-"5 torr and system is now working satisfactorily. (author)

Feasibility of lunar Helium-3 mining

Science.gov (United States)

Kleinschneider, Andreas; Van Overstraeten, Dmitry; Van der Reijnst, Roy; Van Hoorn, Niels; Lamers, Marvin; Hubert, Laurent; Dijk, Bert; Blangé, Joey; Hogeveen, Joel; De Boer, Lennaert; Noomen, Ron

With fossil fuels running out and global energy demand increasing, the need for alternative energy sources is apparent. Nuclear fusion using Helium-3 may be a solution. Helium-3 is a rare isotope on Earth, but it is abundant on the Moon. Throughout the space community lunar Helium-3 is often cited as a major reason to return to the Moon. Despite the potential of lunar Helium-3 mining, little research has been conducted on a full end-to-end mission. This abstract presents the results of a feasibility study conducted by students from Delft University of Technology. The goal of the study was to assess whether a continuous end-to-end mission to mine Helium-3 on the Moon and return it to Earth is a viable option for the future energy market. The set requirements for the representative end-to-end mission were to provide 10% of the global energy demand in the year 2040. The mission elements have been selected with multiple trade-offs among both conservative and novel concepts. A mission architecture with multiple decoupled elements for each transportation segment (LEO, transfer, lunar surface) was found to be the best option. It was found that the most critical element is the lunar mining operation itself. To supply 10% of the global energy demand in 2040, 200 tons of Helium-3 would be required per year. The resulting regolith mining rate would be 630 tons per second, based on an optimistic concentration of 20 ppb Helium-3 in lunar regolith. Between 1,700 to 2,000 Helium-3 mining vehicles would be required, if using University of Wisconsin’s Mark III miner. The required heating power, if mining both day and night, would add up to 39 GW. The resulting power system mass for the lunar operations would be in the order of 60,000 to 200,000 tons. A fleet of three lunar ascent/descent vehicles and 22 continuous-thrust vehicles for orbit transfer would be required. The costs of the mission elements have been spread out over expected lifetimes. The resulting profits from Helium

CFD Simulation of Heat and Fluid Flow for Spent Fuel in a Dry Storage

International Nuclear Information System (INIS)

In, Wangkee; Kwack, Youngkyun; Kook, Donghak; Koo, Yanghyun

2014-01-01

A dry storage system is used for the interim storage of spent fuel prior to permanent depository and/or recycling. The spent fuel is initially stored in a water pool for more than 5 years at least after dispatch from the reactor core and is transported to dry storage. The dry cask contains a multiple number of spent fuel assemblies, which are cooled down in the spent fuel pool. The dry cask is usually filled up with helium gas for increasing the heat transfer to the environment outside the cask. The dry storage system has been used for more than a decade in United States of America (USA) and the European Union (EU). Korea is also developing a dry storage system since its spent fuel pool is anticipated to be full within 10 years. The spent fuel will be stored in a dry cask for more than 40 years. The integrity and safety of spent fuel are important for long-term dry storage. The long-term storage will experience the degradation of spent fuel such as the embrittlement of fuel cladding, thermal creep and hydride reorientation. High burn-up fuel may expedite the material degradation. It is known that the cladding temperature has a strong influence on the material degradation. Hence, it is necessary to accurately predict the local distribution of the cladding temperature using the Computational Fluid Dynamics (CFD) approach. The objective of this study is to apply the CFD method for predicting the three-dimensional distribution of fuel temperature in a dry cask. This CFD study simulated the dry cask for containing the 21 fuel assemblies under development in Korea. This paper presents the fluid velocity and temperature distribution as well as the fuel temperature. A two-step CFD approach was applied to simulate the heat and fluid flow in a dry storage of 21 spent fuel assemblies. The first CFD analysis predicted the helium flow and temperature in a dry cask by a assuming porous body of the spent fuel. The second CFD analysis was to simulate a spent fuel assembly in the

KSTAR Helium Refrigeration System Design and Manufacturing

International Nuclear Information System (INIS)

Dauguet, P.; Briend, P.; Abe, I.; Fauve, E.; Bernhardt, J.-M.; Andrieu, F.; Beauvisage, J.

2006-01-01

The tokamak developed in the KSTAR (Korean Superconducting Tokamak Advanced Research) project makes intensive use of superconducting magnets operated at 4.5 K. The cold components of the KSTAR tokamak require forced flow of supercritical helium for magnets/structure, boiling liquid helium for current leads, and gaseous helium for thermal shields. The cryogenic system will provide stable operation and full automatic control. A three-pressure helium cycle composed of six turbines has been customised design for this project. The '' design '' operating mode results with a system composed of a 9 kW refrigerator (including safety margin) and using gas and liquid storages for mass balancing. During Shot/Standby mode, the heat loads are highly time-dependent. A thermal damper is used to smooth these variations and will allow stable operation. (author)

Annealing dislocation loops in OKh16N15M3T steel implanted by helium

International Nuclear Information System (INIS)

Utkelbaev, B.D.; Reutov, V.F.; Zhdan, G.T.

1993-01-01

With the use of electron microscopy a study was made into the influence of preliminary thermomechanical treatment on the process of dislocation loop development in austenitic stainless steel type OKh16N15M3T with helium on annealing. Preliminary treatment was shown to prevent dislocation loop formation to a greater or lesser extent. Preliminary 'cold' working and thermal ageing of the material are the most effective ways to suppress radiation defect formation when annealing helium implanted steel

The problem of helium in structural materials for fusion reactor

International Nuclear Information System (INIS)

Nikiforov, A.S.; Zakharov, A.P.; Chuev, V.I.

1982-01-01

The processes of helium buildup in some metals and alloys at different energy neutron flux irradiation under thermonuclear reactor conditions are considered. The data on high temperature helium embrittlement of a number of stainless steels, titanium and aluminium alloys etc. are given A review of experiments concerning the implanted helium behaviour is presented. Possible reactions between helium atoms and point defects or their clusters are discussed. Analysed are material structure variations upon buildup in them up to 1 at % of helium

Second sound shock waves in rotating superfluid helium

International Nuclear Information System (INIS)

Torczynski, J.R.

1983-01-01

Second sound shock waves have been used to examine the breakdown of superfluidity in bulk He II. The maximum counterflow velocity achieved in this manner was measured at a variety of temperatures and pressures. The results are found to agree with predictions of vortex nucleation theories (Langer and Fisher, 1967) in their pressure and temperature dependences although it was shown that dissipation occurred only near the heater. A simple scaling argument is suggested, assuming breakdown occurs near the heater. A vortex dynamics model of breakdown (following the method of Turner, private communication) is developed. To examine the effect of vorticity on breakdown, second sound shocks were produced in rotating helium. Experiments were performed in which the shocks propagated either along or normal to the axis of rotation, called axial and transverse cases, respectively. In both cases the decay was seen to increase monotonically with the rotation rate. Furthermore, the decay was ongoing rather than being confined to a narrow region near the heater. However, the extraordinary dissipation in the transverse case seemed to be related primarily to the arrival of secondary waves from the heater-sidewall boundary. An explanation of this difference is put forth in terms of vortex nucleation in the bulk fluid, using ideas similar to Crocco's Theorem. In order to examine the breakdown of superfluidity away from walls in nonrotation fluid, spherically converging second shocks were produced. The temperature jumps of the waves were measured, and exact numerical solutions of the two-fluid jump conditions (Moody, 1983) were used to calculate the relative velocity in each case

Helium solubility and bubble growth in metals under high pressure

International Nuclear Information System (INIS)

Laakmann, J.

1985-07-01

Helium solubility and bubble growth in metals under high pressure polycrystals and single crystals of gold were heated in helium at temperatures between 475 K and 1250 K in a pressure regime of 200 to 2700 bar to measure the solubility of helium in gold. After quenching to room temperature the helium content, measured by mass spectrometry, showed the following properties: 1) A linear dependence of the He solubility on pressure. 2) Thinning of the specimen reduces the helium content by a factor 10 to 100 but does not change the linear pressure dependence. 3) The thermal release of He from thinned polycrystals and single crystals occurs mainly in a single peak at 500 K. 4) The He concentration of the thinned single crystals was lower by a factor of 10 to 50 than that of the thinned polycrystals. 5) The He solubility in single crystals can be described by an enthalpy of solution Hsub(s)sup(f) = 0.85 +- 0.7 eV and a non-configurational entropy of Ssub(s)sup(f) between 0 k and 1 k (k: Boltzmann-constant). In order to measure the pressure dependence of helium bubble growth in nickel polycrystal Ni-foils were α-implanted to a helium content of 130 appm. The evaluation of the size distribution of the helium bubbles after heat treatments shows 1) The helium content of the observable bubbles - assumed to be in equilibrium - equals the amount of helium implanted into the specimen. 2) The activation energy for the growth of helium bubbles is 1.25 +- 0.3 eV. The comparison of specimen which had been heated at low pressures up to 10 bar with others heated at 2500-2700 bar does not show an unequivocal pressure dependence for helium bubble growth. (orig./IHOE) [de

Helium effect on mechanical property of fusion reactor structural materials

International Nuclear Information System (INIS)

Yamamoto, Norikazu; Chuto, Toshinori; Murase, Yoshiharu; Nakagawa, Johsei

2004-01-01

High-energy neutrons produced in fusion reactor core caused helium in the structural materials of fusion reactors, such as blankets. We injected alpha particles accelerated by the cyclotron to the samples of martensite steel (9Cr3WVTaB). Equivalent helium doses injected to the sample is estimated to be up to 300 ppm, which were estimated to be equivalent to helium accumulation after the 1-year reactor operation. Creep tests of the samples were made to investigate helium embrittlement. There were no appreciable changes in the relation between the stresses and the rupture time, the minimum creep rate and the applied stress. Grain boundary effect by helium was not observed in ruptured surfaces. Fatigue tests were made for SUS304 samples, which contain helium up to 150 ppm. After 0.05 Hz cyclic stress tests, it was shown that the fatigue lifetime (cycles to rupture and extension to failure) are 1/5 in 150 ppm helium samples compared with no helium samples. The experimental results suggest martensite steel is promising for structural materials of fusion reactors. (Y. Tanaka)

Comment on theories for helium-assisted void nucleation

International Nuclear Information System (INIS)

Russell, K.C.

1976-01-01

Voids form by agglomeration of irradiation-induced vacancies which remain after preferential absorption of self interstitials at dislocation lines. Helium which is formed by (n,α) transmutations and, in simulation studies, may be ion-implanted, often plays an important, but puzzling role. In some materials, very few voids form in the absence of helium, even after intense irradiation. In many other materials , voids form readily under a variety of irradiation conditions, even in the absence of helium. Why some materials require helium - typically in the 10 -6 apa (atom per atom) range - and others do not, and the reason for that particular level are by no means clear. The physics of void nucleation, particularly the role of helium, have been the subject of several theoretical papers. This note presents a critique of these theories, and then briefly outlines a new analysis which is not subject to their limitations. (Auth.)

Heat-balance integral method for heat transfer in superfluid helium

Directory of Open Access Journals (Sweden)

Baudouy Bertrand

2009-01-01

Full Text Available The heat-balance integral method is used to solve the non-linear heat diffusion equation in static turbulent superfluid helium (He II. Although this is an approximate method, it has proven that it gives solutions with fairly good accuracy in non-linear fluid dynamics and heat transfer. Using this method, it has been possible to develop predictive solutions that reproduce analytical solution and experimental data. We present the solutions of the clamped heat flux case and the clamped temperature case in a semi-infinite using independent variable transformation to take account of temperature dependency of the thermophysical properties. Good accuracy is obtained using the Kirchhoff transform whereas the method fails with the Goodman transform for larger temperature range.

Performance Analysis and Working Fluid Selection of a Supercritical Organic Rankine Cycle for Low Grade Waste Heat Recovery

Directory of Open Access Journals (Sweden)

Yourong Li

2012-08-01

Full Text Available The performance analysis of a supercritical organic Rankine cycle system driven by exhaust heat using 18 organic working fluids is presented. Several parameters, such as the net power output, exergy efficiency, expander size parameter (SP, and heat exchanger requirement of evaporator and the condenser, were used to evaluate the performance of this recovery cycle and screen the working fluids. The results reveal that in most cases, raising the expander inlet temperature is helpful to improve the net power output and the exergy efficiency. However, the effect of the expander inlet pressure on those parameters is related to the expander inlet temperature and working fluid used. Either lower expander inlet temperature and pressure, or higher expander inlet temperature and pressure, generally makes the net power output more. Lower expander inlet temperature results in larger total heat transfer requirement and expander size. According to the screening criteria of both the higher output and the lower investment, the following working fluids for the supercritical ORC system are recommended: R152a and R143a.

Adsorption pump for helium pumping out

International Nuclear Information System (INIS)

Donde, A.L.; Semenenko, Yu.E.

1981-01-01

Adsorption pump with adsorbent cooling by liquid helium is described. Shuttered shield protecting adsorbent against radiation is cooled with evaporating helium passing along the coil positioned on the shield. The pump is also equipped with primed cylindrical shield, cooled with liquid nitrogen. The nitrogen shield has in the lower part the shuttered shield, on the pump casing there is a valve used for pump pre-burning, and valves for connection to recipient as well. Pumping- out rates are presented at different pressures and temperatures of adsorbent. The pumping-out rate according to air at absorbent cooling with liquid nitrogen constituted 5x10 -4 Pa-3000 l/s, at 2x10 -2 Pa-630 l/s. During the absorbent cooling with liquid hydrogen the pumping-out rate according to air was at 4x10 -4 Pa-580 l/s, at 2x10 -3 Pa-680 l/s, according to hydrogen - at 8x10 -5 Pa-2500 l/s, at 5x10 -3 Pa-4200 l/s. During adsorbent cooling with liquid helium the rate of pumping-out according to hydrogen at 3x10 5 Pa-2400% l/s, at 6x10 3 Pa-1200 l/s, and according to helium at 3.5x10 -5 Pa-2800 l/s, at 4x10 -3 Pa-1150 l/s. The limit vacuum is equal to 1x10 -7 Pa. The volume of the vessel with liquid helium is equal to 3.5 l. Helium consumption is 80 cm 3 /h. Consumption of liquid nitrogen from the shield is 400 cm 3 /h. The limit pressure in the pump is obtained after forevacuum pumping-out (adsorbent regeneration) at 300 K temperature. The pump is made of copper. The pump height together with primed tubes is 800 mm diameter-380 mm [ru

Blackbody-radiation correction to the polarizability of helium

International Nuclear Information System (INIS)

Puchalski, M.; Jentschura, U. D.; Mohr, P. J.

2011-01-01

The correction to the polarizability of helium due to blackbody radiation is calculated near room temperature. A precise theoretical determination of the blackbody radiation correction to the polarizability of helium is essential for dielectric gas thermometry and for the determination of the Boltzmann constant. We find that the correction, for not too high temperature, is roughly proportional to a modified hyperpolarizability (two-color hyperpolarizability), which is different from the ordinary hyperpolarizability of helium. Our explicit calculations provide a definite numerical result for the effect and indicate that the effect of blackbody radiation can be excluded as a limiting factor for dielectric gas thermometry using helium or argon.

Diffusion of helium in the Sun

Energy Technology Data Exchange (ETDEWEB)

Noerdlinger, P D [Michigan State Univ., East Lansing (USA). Dept. of Astronomy and Astrophysics; Amsterdam Univ. (Netherlands). Sterrenkundig Instituut)

1977-05-01

I have reduced the set of diffusion and flow equations developed by Burgers for a multi-component gas to a workable scheme for the actual evaluation of the relative diffusion of hydrogen and helium in stars. Previous analyses have used the Aller and Chapman equations, which apply only to trace constitutents and whose coefficients are not believed to be as accurate as Burgers'. Furthermore, the resulting equations have been combined consistently with Paczynski's stellar evolution code to demonstrate small but significant effects in the Sun, from the thermal and gravitational settling of Helium. The core helium content of a 1 M star goes up about 0.04 and the surface helium content down by about -0.03 in 4.5 10/sup 9/ years. The results are still somewhat uncertain because of uncertainties in the underlying plasma physics, and further research is suggested. In any case, the diffusion process speeds up with time, due to increased temperature gradient, and it will be of interest to follow the process in older stars and in later stellar evolution.