Measuring gas temperature during spin-exchange optical pumping process

Science.gov (United States)

Normand, E.; Jiang, C. Y.; Brown, D. R.; Robertson, L.; Crow, L.; Tong, X.

2016-04-01

The gas temperature inside a Spin-Exchange Optical Pumping (SEOP) laser-pumping polarized 3He cell has long been a mystery. Different experimental methods were employed to measure this temperature but all were based on either modelling or indirect measurement. To date there has not been any direct experimental measurement of this quantity. Here we present the first direct measurement using neutron transmission to accurately determine the number density of 3He, the temperature is obtained using the ideal gas law. Our result showed a surprisingly high gas temperature of 380°C, compared to the 245°C of the 3He cell wall temperature and 178°C of the optical pumping oven temperature. This experiment result may be used to further investigate the unsolved puzzle of the "X-factor" in the SEOP process which places an upper bound to the 3He polarization that can be achieved. Additional spin relaxation mechanisms might exist due to the high gas temperature, which could explain the origin of the X-factor.

Thermalisation of a two-dimensional photonic gas in a 'white-wall' photon box

OpenAIRE

Klaers, Jan; Vewinger, Frank; Weitz, Martin

2010-01-01

Bose-Einstein condensation, the macroscopic accumulation of bosonic particles in the energetic ground state below a critical temperature, has been demonstrated in several physical systems. The perhaps best known example of a bosonic gas, blackbody radiation, however exhibits no Bose-Einstein condensation at low temperatures. Instead of collectively occupying the lowest energy mode, the photons disappear in the cavity walls when the temperature is lowered - corresponding to a vanishing chemica...

Thermalization of a two-dimensional photonic gas in a `white wall' photon box

Science.gov (United States)

Klaers, Jan; Vewinger, Frank; Weitz, Martin

2010-07-01

Bose-Einstein condensation, the macroscopic accumulation of bosonic particles in the energetic ground state below a critical temperature, has been demonstrated in several physical systems. The perhaps best known example of a bosonic gas, blackbody radiation, however exhibits no Bose-Einstein condensation at low temperatures. Instead of collectively occupying the lowest energy mode, the photons disappear in the cavity walls when the temperature is lowered-corresponding to a vanishing chemical potential. Here we report on evidence for a thermalized two-dimensional photon gas with a freely adjustable chemical potential. Our experiment is based on a dye-filled optical microresonator, acting as a `white wall' box for photons. Thermalization is achieved in a photon-number-conserving way by photon scattering off the dye molecules, and the cavity mirrors provide both an effective photon mass and a confining potential-key prerequisites for the Bose-Einstein condensation of photons. As a striking example of the unusual system properties, we demonstrate a yet unobserved light concentration effect into the centre of the confining potential, an effect with prospects for increasing the efficiency of diffuse solar light collection.

Measurement of gas species, temperatures, coal burnout, and wall heat fluxes in a 200 MWe lignite-fired boiler with different overfire air damper openings

Energy Technology Data Exchange (ETDEWEB)

Jianping Jing; Zhengqi Li; Guangkui Liu; Zhichao Chen; Chunlong Liu [Harbin Institute of Technology, Harbin (China). School of Energy Science and Engineering

2009-07-15

Measurements were performed on a 200 MWe, wall-fired, lignite utility boiler. For different overfire air (OFA) damper openings, the gas temperature, gas species concentration, coal burnout, release rates of components (C, H, and N), furnace temperature, and heat flux and boiler efficiency were measured. Cold air experiments for a single burner were conducted in the laboratory. The double-swirl flow pulverized-coal burner has two ring recirculation zones starting in the secondary air region in the burner. As the secondary air flow increases, the axial velocity of air flow increases, the maxima of radial velocity, tangential velocity and turbulence intensity all increase, and the swirl intensity of air flow and the size of recirculation zones increase slightly. In the central region of the burner, as the OFA damper opening widens, the gas temperature and CO concentration increase, while the O{sub 2} concentration, NOx concentration, coal burnout, and release rates of components (C, H, and N) decrease, and coal particles ignite earlier. In the secondary air region of the burner, the O{sub 2} concentration, NOx concentration, coal burnout, and release rates of components (C, H, and N) decrease, and the gas temperature and CO concentration vary slightly. In the sidewall region, the gas temperature, O{sub 2} concentration, and NOx concentration decrease, while the CO concentration increases and the gas temperature varies slightly. The furnace temperature and heat flux in the main burning region decrease appreciably, but increase slightly in the burnout region. The NOx emission decreases from 1203.6 mg/m{sup 3} (6% O{sub 2}) for a damper opening of 0% to 511.7 mg/m{sup 3} (6% O{sub 2}) for a damper opening of 80% and the boiler efficiency decreases from 92.59 to 91.9%. 15 refs., 17 figs., 3 tabs.

Fuel retention under elevated wall temperature in KSTAR with a carbon wall

Science.gov (United States)

Cao, B.; Hong, S. H.

2018-03-01

The fuel retention during KSTAR discharges with elevated wall temperature (150 °C) has been studied by using the method of global particle balance. The results show that the elevated wall temperature could reduce the dynamic retention via implantation and absorption, especially for the short pulse shots with large injected fuel particles. There is no signature changing of long-term retention, which related to co-deposition, under elevated wall temperature. For soft-landing shots (normal shots), the exhausted fuel particles during discharges is larger with elevated wall temperature than without, but the exhausted particles after discharges within 90 s looks similar. The outgassing particles because of disruption could be exhausted within 15 s.

Conjugated heat transfer and temperature distributions in a gas turbine combustion liner under base-load operation

International Nuclear Information System (INIS)

Kim, Kyung Min; Yun, Nam Geon; Jeon, Yun Heung; Lee, Dong Hyun; Cho, Yung Hee

2010-01-01

Prediction of temperature distributions on hot components is important in development of a gas turbine combustion liner. The present study investigated conjugated heat transfer to obtain temperature distributions in a combustion liner with six combustion nozzles. 3D numerical simulations using FVM commercial codes, Fluent and CFX were performed to calculate combustion and heat transfer distributions. The temperature distributions in the combustor liner were calculated by conjugation of conduction and convection (heat transfer coefficients) obtained by combustion and cooling flow analysis. The wall temperature was the highest on the attachment points of the combustion gas from combustion nozzles, but the temperature gradient was high at the after shell section with low wall temperature

Method for determining waveguide temperature for acoustic transceiver used in a gas turbine engine

Science.gov (United States)

DeSilva, Upul P.; Claussen, Heiko; Ragunathan, Karthik

2018-04-17

A method for determining waveguide temperature for at least one waveguide of a transceiver utilized for generating a temperature map. The transceiver generates an acoustic signal that travels through a measurement space in a hot gas flow path defined by a wall such as in a combustor. The method includes calculating a total time of flight for the acoustic signal and subtracting a waveguide travel time from the total time of flight to obtain a measurement space travel time. A temperature map is calculated based on the measurement space travel time. An estimated wall temperature is obtained from the temperature map. An estimated waveguide temperature is then calculated based on the estimated wall temperature wherein the estimated waveguide temperature is determined without the use of a temperature sensing device.

Radiometric measurements of wall temperatures in the 800 K to 1150 K range for a quartz radiant heating tube

International Nuclear Information System (INIS)

Blevins, L.G.; Sivathanu, Y.R.; Gore, J.P.; Shahien, M.A.

1995-01-01

Many industrial applications require heat transfer to a load in an inert environment, which can be achieved by using gas-fired radiant tubes. A radiant tube consists of a flame confined in a cylindrical metal or ceramic chamber. The flame heats the tube wall, which in turn radiates to the load. One important characteristic of radiant heating tubes is wall temperature uniformity. Numerical models of radiant tubes have been used to predict wall temperatures, but there is a lack of experimental data for validation. Recently, Namazian et al., Singh and Gorski, and Peters et al. have measured wall temperature profiles of radiant tubes using thermocouples. 13 refs., 3 figs

The Coupling Effect Research of Ash Deposition and Condensation in Low Temperature Flue Gas

Directory of Open Access Journals (Sweden)

Lei Ma

2016-01-01

Full Text Available Ash deposition is a key factor that deteriorates the heat transfer performance and leads to higher energy consumption of low pressure economizer working in low temperature flue gas. In order to study the ash deposition of heat exchange tubes in low temperature flue gas, two experiments are carried out with different types of heat exchange tubes in different flue gas environments. In this paper, Nusselt Number Nu and fouling factor ε are calculated to describe the heat transfer characteristics so as to study the ash deposition condition. The scanning electron microscope (SEM is used for the analysis of ash samples obtained from the outer wall of heat exchange tubes. The dynamic process of ash deposition is studied under different temperatures of outer wall. The results showed that ash deposition of heat exchanger will achieve a stable state in constant flue gas environment. According to the condition of condensation of acid vapor and water vapor, the process of ash deposition can be distinguished as mere ash deposition, acid-ash coupling deposition, and acid-water-ash coupling deposition.

Gas Near a Wall: Shortened Mean Free Path, Reduced Viscosity, and the Manifestation of the Knudsen Layer in the Navier-Stokes Solution of a Shear Flow

Science.gov (United States)

Abramov, Rafail V.

2018-06-01

For the gas near a solid planar wall, we propose a scaling formula for the mean free path of a molecule as a function of the distance from the wall, under the assumption of a uniform distribution of the incident directions of the molecular free flight. We subsequently impose the same scaling onto the viscosity of the gas near the wall and compute the Navier-Stokes solution of the velocity of a shear flow parallel to the wall. Under the simplifying assumption of constant temperature of the gas, the velocity profile becomes an explicit nonlinear function of the distance from the wall and exhibits a Knudsen boundary layer near the wall. To verify the validity of the obtained formula, we perform the Direct Simulation Monte Carlo computations for the shear flow of argon and nitrogen at normal density and temperature. We find excellent agreement between our velocity approximation and the computed DSMC velocity profiles both within the Knudsen boundary layer and away from it.

The dynamic characteristics of HTGR (High Temperature Gas Cooled Reactor) system, (2)

International Nuclear Information System (INIS)

Kudo, Kazuhiko; Ohta, Masao; Kawasaki, Hidenori

1979-01-01

The dynamic characteristics of a HTGR plant, which has two cooling loops, was investigated. The analytical model consists of the core with fuel sleeves, coolant channels and blocks, the upper and lower reflectors, the high and low temperature plenums, two double wall pipings, two intermediate heat exchangers and the secondary system. The key plant parameters for calculation were as follows: the core outlet gas temperature 1000 deg C, the reactor thermal output 50 MW, the flow rate of primary coolant gas 7.96 kg/sec-loop and the pressure of primary coolant gas 40 kg/cm 2 at the rated operating condition. The calculating parameters were fixed as follows: the time interval for core characteristic analysis 0.1 sec, the time interval for thermal characteristic analysis 5.0 sec, the number of division of fuel channels 130, and the number of division of an intermediate heat exchanger 200. The assumptions for making the model were evaluated especially for the power distribution in the core and the heat transmission coefficients in the core, the double wall piping and the intermediate heat exchangers. Concerning the analytical results, the self-control to the outer disturbance of reactivity and the plant dynamic behavior due to the change of flow rate of primary and secondary coolants, and the change of gas temperature of secondary coolant at the inlet of intermediate heat exchangers, are presented. (Nakai, Y.)

Wall-to-bed heat transfer in gas-solid fluidized beds: a computational and experimental study

NARCIS (Netherlands)

Patil, D.J.; Smit, J.; van Sint Annaland, M.; Kuipers, J.A.M.

2006-01-01

The wall-to-bed heat transfer in gas-solid fluidized beds is mainly determined by phenomena prevailing in a thermal boundary layer with a thickness in the order of magnitude of the size of a single particle. In this thermal boundary layer the temperature gradients are very steep and the local

Temperature measurements in a wall stabilized steady flame using CARS

KAUST Repository

Sesha Giri, Krishna

2017-01-05

Flame quenching by heat loss to a surface continues to be an active area of combustion research. Close wall temperature measurements in an isothermal wall-stabilized flame are reported in this work. Conventional N-vibrational Coherent Anti-Stokes Raman Scattering (CARS) thermometry as close as 275 μm to a convex wall cooled with water has been carried out. The standard deviation of mean temperatures is observed to be ~6.5% for high temperatures (>2000K) and ~14% in the lower range (<500K). Methane/air and ethylene/air stoichiometric flames for various global strain rates based on exit bulk velocities are plotted and compared. CH* chemiluminescence is employed to determine the flame location relative to the wall. Flame locations are shown to move closer to the wall with increasing strain rates in addition to higher near-wall temperatures. Peak temperatures for ethylene are considerably higher (~250-300K) than peak temperatures for methane. Preheat zone profiles are similar for different strain rates across fuels. This work demonstrates close wall precise temperature measurments using CARS.

Domain walls at finite temperature

International Nuclear Information System (INIS)

Carvalho, C.A. de; Marques, G.C.; Silva, A.J. da; Ventura, I.

1983-08-01

It is suggested that the phase transition of lambda phi 4 theory as a function of temperature coincides with the spontaneous appearance of domain walls. Based on one-loop calculations, T sub(c) = 4M/√ lambda is estimated as the temperature for these domains to because energetically favored, to be compared with T sub(c) = 4.9M/√ lambda from effective potential calculations (which are performed directly in the broken phase). Domain walls, as well as other Types of fluctuations, disorder the system above T sub(c), leading to =0. The critical exponent for the specific heat above T sub(c) is computed; and α=2/3 + 0 (√ lambda) is obtained. (Author) [pt

Flue gas adsorption by single-wall carbon nanotubes: A Monte Carlo study.

Science.gov (United States)

Romero-Hermida, M I; Romero-Enrique, J M; Morales-Flórez, V; Esquivias, L

2016-08-21

Adsorption of flue gases by single-wall carbon nanotubes (SWCNT) has been studied by means of Monte Carlo simulations. The flue gas is modeled as a ternary mixture of N2, CO2, and O2, emulating realistic compositions of the emissions from power plants. The adsorbed flue gas is in equilibrium with a bulk gas characterized by temperature T, pressure p, and mixture composition. We have considered different SWCNTs with different chiralities and diameters in a range between 7 and 20 Å. Our results show that the CO2 adsorption properties depend mainly on the bulk flue gas thermodynamic conditions and the SWCNT diameter. Narrow SWCNTs with diameter around 7 Å show high CO2 adsorption capacity and selectivity, but they decrease abruptly as the SWCNT diameter is increased. For wide SWCNT, CO2 adsorption capacity and selectivity, much smaller in value than for the narrow case, decrease mildly with the SWCNT diameter. In the intermediate range of SWCNT diameters, the CO2 adsorption properties may show a peculiar behavior, which depend strongly on the bulk flue gas conditions. Thus, for high bulk CO2 concentrations and low temperatures, the CO2 adsorption capacity remains high in a wide range of SWCNT diameters, although the corresponding selectivity is moderate. We correlate these findings with the microscopic structure of the adsorbed gas inside the SWCNTs.

Flue gas adsorption by single-wall carbon nanotubes: A Monte Carlo study

International Nuclear Information System (INIS)

Romero-Hermida, M. I.; Romero-Enrique, J. M.; Morales-Flórez, V.; Esquivias, L.

2016-01-01

Adsorption of flue gases by single-wall carbon nanotubes (SWCNT) has been studied by means of Monte Carlo simulations. The flue gas is modeled as a ternary mixture of N 2 , CO 2 , and O 2 , emulating realistic compositions of the emissions from power plants. The adsorbed flue gas is in equilibrium with a bulk gas characterized by temperature T, pressure p, and mixture composition. We have considered different SWCNTs with different chiralities and diameters in a range between 7 and 20 Å. Our results show that the CO 2 adsorption properties depend mainly on the bulk flue gas thermodynamic conditions and the SWCNT diameter. Narrow SWCNTs with diameter around 7 Å show high CO 2 adsorption capacity and selectivity, but they decrease abruptly as the SWCNT diameter is increased. For wide SWCNT, CO 2 adsorption capacity and selectivity, much smaller in value than for the narrow case, decrease mildly with the SWCNT diameter. In the intermediate range of SWCNT diameters, the CO 2 adsorption properties may show a peculiar behavior, which depend strongly on the bulk flue gas conditions. Thus, for high bulk CO 2 concentrations and low temperatures, the CO 2 adsorption capacity remains high in a wide range of SWCNT diameters, although the corresponding selectivity is moderate. We correlate these findings with the microscopic structure of the adsorbed gas inside the SWCNTs.

A Single-Walled Carbon Nanotube Network Gas Sensing Device

Directory of Open Access Journals (Sweden)

I-Ju Teng

2011-08-01

Full Text Available The goal of this research was to develop a chemical gas sensing device based on single-walled carbon nanotube (SWCNT networks. The SWCNT networks are synthesized on Al2O3-deposted SiO2/Si substrates with 10 nm-thick Fe as the catalyst precursor layer using microwave plasma chemical vapor deposition (MPCVD. The development of interconnected SWCNT networks can be exploited to recognize the identities of different chemical gases by the strength of their particular surface adsorptive and desorptive responses to various types of chemical vapors. The physical responses on the surface of the SWCNT networks cause superficial changes in the electric charge that can be converted into electronic signals for identification. In this study, we tested NO2 and NH3 vapors at ppm levels at room temperature with our self-made gas sensing device, which was able to obtain responses to sensitivity changes with a concentration of 10 ppm for NO2 and 24 ppm for NH3.

Estimation of gas wall shear stress in horizontal stratified gas-liquid pipe flow

International Nuclear Information System (INIS)

Newton, C.H.; Behnia, M.

1996-01-01

Two-phase pipe flows occur in many industrial applications, such as condensers and evaporators, chemical processing equipment, nuclear reactors, and oil pipelines. A variety of basic mechanistic flow models for predicting the pressure gradient and liquid loading characteristics of these types of flows to assist in design calculations has emerged over the past two decades, especially for the stratified and slug flow regimes. These models generally rely on a number of basic assumptions and empirical closure equations. Possibly the most notable of these relates to the evaluation of interfacial shear stresses. However, one of the most important yet least discussed assumptions used in most of these models is that the phase wall shear stresses can be accurately estimated from correlations developed for single-phase pipe flows. The object of this article is to present measurements of gas wall shear up to locations in close proximity to the gas-liquid interface for a variety of interface conditions in developed flow, and to determine the effects of the interface on average gas wall friction factors. In this context the interface may be smooth, rippled or wavy

Temperature dependence of photoconductivity at 0.7 eV in single-wall carbon nanotube films

Directory of Open Access Journals (Sweden)

Yukitaka Matsuoka, Akihiko Fujiwara, Naoki Ogawa, Kenjiro Miyano, Hiromichi Kataura, Yutaka Maniwa, Shinzo Suzuki and Yohji Achiba

2003-01-01

Full Text Available Temperature dependence of photoconductivity has been investigated for single-wall carbon nanotube films at 0.7 eV. In order to clarify the effect of atmosphere on photoconductivity, measurements have been performed under helium and nitrogen gas flow in the temperature range from 10 K to room temperature (RT and from 100 K to RT, respectively. Photoconductive response monotonously increases with a decrease in temperature and tends to saturate around 10 K. No clear difference in photoconductive response under different atmosphere was observed. We discuss the mechanism of photoconductivity at 0.7 eV.

Flue gas adsorption by single-wall carbon nanotubes: A Monte Carlo study

Energy Technology Data Exchange (ETDEWEB)

Romero-Hermida, M. I. [Departamento de Química Física, Facultad de Ciencias, Universidad de Cádiz, Campus Río San Pedro s/n, 11510 Puerto Real (Spain); Departamento de Física Condensada, Universidad de Sevilla, Av. Reina Mercedes s/n, 41012 Sevilla (Spain); Romero-Enrique, J. M. [Departamento de Física Atómica, Molecular y Nuclear, Área de Física Teórica, Universidad de Sevilla, Av. Reina Mercedes s/n, 41012 Sevilla (Spain); Morales-Flórez, V.; Esquivias, L. [Departamento de Física Condensada, Universidad de Sevilla, Av. Reina Mercedes s/n, 41012 Sevilla (Spain); Instituto de Ciencia de Materiales de Sevilla (CSIC/US), Av. Américo Vespucio 49, 41092 Sevilla (Spain)

2016-08-21

Adsorption of flue gases by single-wall carbon nanotubes (SWCNT) has been studied by means of Monte Carlo simulations. The flue gas is modeled as a ternary mixture of N{sub 2}, CO{sub 2}, and O{sub 2}, emulating realistic compositions of the emissions from power plants. The adsorbed flue gas is in equilibrium with a bulk gas characterized by temperature T, pressure p, and mixture composition. We have considered different SWCNTs with different chiralities and diameters in a range between 7 and 20 Å. Our results show that the CO{sub 2} adsorption properties depend mainly on the bulk flue gas thermodynamic conditions and the SWCNT diameter. Narrow SWCNTs with diameter around 7 Å show high CO{sub 2} adsorption capacity and selectivity, but they decrease abruptly as the SWCNT diameter is increased. For wide SWCNT, CO{sub 2} adsorption capacity and selectivity, much smaller in value than for the narrow case, decrease mildly with the SWCNT diameter. In the intermediate range of SWCNT diameters, the CO{sub 2} adsorption properties may show a peculiar behavior, which depend strongly on the bulk flue gas conditions. Thus, for high bulk CO{sub 2} concentrations and low temperatures, the CO{sub 2} adsorption capacity remains high in a wide range of SWCNT diameters, although the corresponding selectivity is moderate. We correlate these findings with the microscopic structure of the adsorbed gas inside the SWCNTs.

Inverse heat conduction estimation of inner wall temperature fluctuations under turbulent penetration

Science.gov (United States)

Guo, Zhouchao; Lu, Tao; Liu, Bo

2017-04-01

Turbulent penetration can occur when hot and cold fluids mix in a horizontal T-junction pipe at nuclear plants. Caused by the unstable turbulent penetration, temperature fluctuations with large amplitude and high frequency can lead to time-varying wall thermal stress and even thermal fatigue on the inner wall. Numerous cases, however, exist where inner wall temperatures cannot be measured and only outer wall temperature measurements are feasible. Therefore, it is one of the popular research areas in nuclear science and engineering to estimate temperature fluctuations on the inner wall from measurements of outer wall temperatures without damaging the structure of the pipe. In this study, both the one-dimensional (1D) and the two-dimensional (2D) inverse heat conduction problem (IHCP) were solved to estimate the temperature fluctuations on the inner wall. First, numerical models of both the 1D and the 2D direct heat conduction problem (DHCP) were structured in MATLAB, based on the finite difference method with an implicit scheme. Second, both the 1D IHCP and the 2D IHCP were solved by the steepest descent method (SDM), and the DHCP results of temperatures on the outer wall were used to estimate the temperature fluctuations on the inner wall. Third, we compared the temperature fluctuations on the inner wall estimated by the 1D IHCP with those estimated by the 2D IHCP in four cases: (1) when the maximum disturbance of temperature of fluid inside the pipe was 3°C, (2) when the maximum disturbance of temperature of fluid inside the pipe was 30°C, (3) when the maximum disturbance of temperature of fluid inside the pipe was 160°C, and (4) when the fluid temperatures inside the pipe were random from 50°C to 210°C.

Effects of wall temperature on skin-friction measurements by oil-film interferometry

International Nuclear Information System (INIS)

Bottini, H; Kurita, M; Iijima, H; Fukagata, K

2015-01-01

Wind-tunnel skin-friction measurements with thin-oil-film interferometry have been taken on an aluminum sample to investigate the effects of wall temperature on the accuracy of the technique. The sample has been flush-mounted onto a flat plate with an electric heater at its bottom and mirror-smooth temperature-sensitive paint sprayed on its top. The heater has varied the sample temperature from ambient to 328 K, and the paint has permitted wall temperature measurements on the same area of the skin-friction measurements and during the same test. The measured wall temperatures have been used to calculate the correct oil viscosities, and these viscosities and the constant nominal viscosity at 298 K have been used to calculate two different sets of skin-friction coefficients. These sets have been compared to each other and with theoretical values. This comparison shows that the effects of wall temperature on the accuracy of skin-friction measurements are sensible, and more so as wall temperature differs from 298 K. Nonetheless, they are effectively neutralized by the use of wall temperature measurements in combination with the correct oil viscosity–temperature law. In this regard, the special temperature-sensitive paint developed for this study shows advantages with respect to more traditional wall temperature measurement techniques. (paper)

Fuel retention properties of thin-wall glass target in low temperature

International Nuclear Information System (INIS)

Gao Dangzhong; Huang Yong; Tang Yongjian; Wen Shuhuai

2001-01-01

In room temperature the fuel gas storage half-life of the thin-wall (wall-thickness less than 1μm) glass microsphere is only a few days, it is difficult to be used for ICF. To efficiently prolong the half-life of such type targets, and meet the need of ICF experiments, the special device for storing the targets was developed. All the targets are immerged in liquid-nitrogen (LN 2 ), after being sealed in vacuum. During this period the change of Si 1.74 keV X-ray counts were measured a few times with the low energy X-ray multi-channel analyzer. The results of experiment indicate that, in the environment of -196 degree C, the fuel storage half-life of target has been successfully extended to 100-300 d from 3-10 d. However, the surface roughness of target was not obviously changed

On the assumption of vanishing temperature fluctuations at the wall for heat transfer modeling

Science.gov (United States)

Sommer, T. P.; So, R. M. C.; Zhang, H. S.

1993-01-01

Boundary conditions for fluctuating wall temperature are required for near-wall heat transfer modeling. However, their correct specifications for arbitrary thermal boundary conditions are not clear. The conventional approach is to assume zero fluctuating wall temperature or zero gradient for the temperature variance at the wall. These are idealized specifications and the latter condition could lead to an ill posed problem for fully-developed pipe and channel flows. In this paper, the validity and extent of the zero fluctuating wall temperature condition for heat transfer calculations is examined. The approach taken is to assume a Taylor expansion in the wall normal coordinate for the fluctuating temperature that is general enough to account for both zero and non-zero value at the wall. Turbulent conductivity is calculated from the temperature variance and its dissipation rate. Heat transfer calculations assuming both zero and non-zero fluctuating wall temperature reveal that the zero fluctuating wall temperature assumption is in general valid. The effects of non-zero fluctuating wall temperature are limited only to a very small region near the wall.

Experimental study on the leakage of gas through cracked concrete walls

International Nuclear Information System (INIS)

Suzuki, T.; Takiguchi, K.; Hotta, H.; Kojima, N.; Fukuhara, M.; Kimura, K.

1989-01-01

The air-tightness of concrete walls is important for nuclear-related facilities. A concrete wall has very high probabilities of developing cracks due to shrinkage, seismic forces or other factors. It is therefore essential to be able to predict the amount of gas which will leak through a cracked concrete wall. In the previous paper published in SmiRT-9, the experimental equation on the gas leakage through a single crack occurred in concrete was presented based on two-dimensional Poiseuille's flow. In this paper, the experimental results were examined again considering the compressibility of gas, and new equation is presented. The experiments which were similar to ones in the previous paper were carried out on several kinds of concrete using several kinds of gases, and the effects of the kinds of gaseous body, particle size of aggregates and shape of aggregates were examined

Numerical investigations of cooling holes system role in the protection of the walls of a gas turbine combustion chamber

Energy Technology Data Exchange (ETDEWEB)

Ben Sik Ali, Ahlem; Kriaa, Wassim; Mhiri, Hatem [Ecole Nationale D' Ingenieurs de Monastir, Unite de Thermique et Thermodynamique des Procedes industriels, Monastir (Tunisia); Bournot, Philippe [IUSTI, UMR CNRS 6595, Marseille (France)

2012-05-15

Numerical simulations in a gas turbine Swirl stabilized combustor were conducted to investigate the effectiveness of a cooling system in the protection of combustor walls. The studied combustion chamber has a high degree of geometrical complexity related to the injection system as well as the cooling system based on a big distribution of small holes (about 3,390 holes) bored on the flame tube walls. Two cases were considered respectively the flame tube without and with its cooling system. The calculations were carried out using the industrial CFD code FLUENT 6.2. The various simulations made it possible to highlight the role of cooling holes in the protection of the flame tube walls against the high temperatures of the combustion products. In fact, the comparison between the results of the two studied cases demonstrated that the walls temperature can be reduced by about 800 C by the mean of cooling holes technique. (orig.)

[Study on Hollow Brick Wall's Surface Temperature with Infrared Thermal Imaging Method].

Science.gov (United States)

Tang, Ming-fang; Yin, Yi-hua

2015-05-01

To address the characteristic of uneven surface temperature of hollow brick wall, the present research adopts soft wares of both ThermaCAM P20 and ThermaCAM Reporter to test the application of infrared thermal image technique in measuring surface temperature of hollow brick wall, and further analyzes the thermal characteristics of hollow brick wall, and building material's impact on surface temperature distribution including hollow brick, masonry mortar, and so on. The research selects the construction site of a three-story-high residential, carries out the heat transfer experiment, and further examines the exterior wall constructed by 3 different hollow bricks including sintering shale hollow brick, masonry mortar and brick masonry. Infrared thermal image maps are collected, including 3 kinds of sintering shale hollow brick walls under indoor heating in winter; and temperature data of wall surface, and uniformity and frequency distribution are also collected for comparative analysis between 2 hollow bricks and 2 kinds of mortar masonry. The results show that improving heat preservation of hollow brick aid masonry mortar can effectively improve inner wall surface temperature and indoor thermal environment; non-uniformity of surface temperature decreases from 0. 6 to 0. 4 °C , and surface temperature frequency distribution changes from the asymmetric distribution into a normal distribution under the condition that energy-saving sintering shale hollow brick wall is constructed by thermal mortar replacing cement mortar masonry; frequency of average temperature increases as uniformity of surface temperature increases. This research provides a certain basis for promotion and optimization of hollow brick wall's thermal function.

Electrochemically decorated ZnTe nanodots on single-walled carbon nanotubes for room-temperature NO2 sensor application.

Science.gov (United States)

Kim, Donguk; Park, Ki-Moon; Shanmugam, Rajakumar; Yoo, Bongyoung

2014-11-01

A gas sensor with ZnTe nanodot-modified single-walled carbon nanotubes (SWCNTs) is demonstrated for NO2 detection at room temperature. ZnTe nanodots are electrochemically deposited in an aqueous solution containing ZnSO4, TeO2 and citrate. A deposition potential range of ZnTe formation of -0.65 to -0.9 V is determined by cyclic voltammetry, and an intermetallic ZnTe compound is formed at above 50 degrees C bath. SWCNT-based sensors show the highly sensitive response down to 1 ppm NO2 gas at room temperature. In particular, the sensitivity of ZnTe nanodot-modified SWCNTs is increased by 6 times as compared to that of pristine SWCNT sensors. A selectivity test of SWCNT-ZnTe nanodots sensors is carried out with ammonia gas (NH3) and methanol vapor (MeOH), and the result confirms an excellent selectivity to NO2 gas.

Finite difference program for calculating hydride bed wall temperature profiles

International Nuclear Information System (INIS)

Klein, J.E.

1992-01-01

A QuickBASIC finite difference program was written for calculating one dimensional temperature profiles in up to two media with flat, cylindrical, or spherical geometries. The development of the program was motivated by the need to calculate maximum temperature differences across the walls of the Tritium metal hydrides beds for thermal fatigue analysis. The purpose of this report is to document the equations and the computer program used to calculate transient wall temperatures in stainless steel hydride vessels. The development of the computer code was motivated by the need to calculate maximum temperature differences across the walls of the hydrides beds in the Tritium Facility for thermal fatigue analysis

Features of reducing the turbulent friction of a liquid on the channel wall by gas-saturation

Directory of Open Access Journals (Sweden)

Evseev Aleksei

2017-01-01

Full Text Available The report presents the results of an experimental study of the efficiency of reducing the local friction at gas saturation of the turbulent boundary layer (TBL in the input section of the channel at different gravitational orientation of the wall, and its dependence on the structure of gas-liquid flow. Profiles of gas concentration have a peak near the wall, which increases with the gas flow increase. The growth of concentration in the near-wall zone leads to rapid coalescence of bubbles, as a result of which the flow in TBL transits to the film-bubble regime with increasing the buoyancy effect of the gas phase, especially at low flow rates. It is shown that the key parameter of friction reduction by gas saturation is the gas phase concentration in the inner region of the boundary layer, whose magnitude is determined by the gas flow rate, the flow velocity, the distance downstream behind the gas generator, and the gravitational orientation of the wall.

The effect of wall temperature distribution on streaks in compressible turbulent boundary layer

Science.gov (United States)

Zhang, Zhao; Tao, Yang; Xiong, Neng; Qian, Fengxue

2018-05-01

The thermal boundary condition at wall is very important for the compressible flow due to the coupling of the energy equation, and a lot of research works about it were carried out in past decades. In most of these works, the wall was assumed as adiabatic or uniform isothermal surface; the flow over a thermal wall with some special temperature distribution was seldom studied. Lagha studied the effect of uniform isothermal wall on the streaks, and pointed out that higher the wall temperature is, the longer the streak (POF, 2011, 23, 015106). So, we designed streamwise stripes of wall temperature distribution on the compressible turbulent boundary layer at Mach 3.0 to learn the effect on the streaks by means of direct numerical simulation in this paper. The mean wall temperature is equal to the adiabatic case approximately, and the width of the temperature stripes is in the same order as the width of the streaks. The streak patterns in near-wall region with different temperature stripes are shown in the paper. Moreover, we find that there is a reduction of friction velocity with the wall temperature stripes when compared with the adiabatic case.

CFD Validation of Gas Injection in Flowing Mercury over Vertical Smooth and Grooved Wall

International Nuclear Information System (INIS)

Abdou, Ashraf A.; Wendel, Mark W.; Felde, David K.; Riemer, Bernie

2009-01-01

The Spallation Neutron Source (SNS) is an accelerator-based neutron source at Oak Ridge National Laboratory (ORNL). The nuclear spallation reaction occurs when a proton beam hits liquid mercury. This interaction causes thermal expansion of the liquid mercury which produces high pressure waves. When these pressure waves hit the target vessel wall, cavitation can occur and erode the wall. Research and development efforts at SNS include creation of a vertical protective gas layer between the flowing liquid mercury and target vessel wall to mitigate the cavitation damage erosion and extend the life time of the target. Since mercury is opaque, computational fluid dynamics (CFD) can be used as a diagnostic tool to see inside the liquid mercury and guide the experimental efforts. In this study, CFD simulations of three dimensional, unsteady, turbulent, two-phase flow of helium gas injection in flowing liquid mercury over smooth, vertically grooved and horizontally grooved walls are carried out with the commercially available CFD code Fluent-12 from ANSYS. The Volume of Fluid (VOF) model is used to track the helium-mercury interface. V-shaped vertical and horizontal grooves with 0.5 mm pitch and about 0.7 mm depth were machined in the transparent wall of acrylic test sections. Flow visualization data of helium gas coverage through transparent test sections is obtained with a high-speed camera at the ORNL target test facility (TTF). The helium gas mass flow rate is 8 mg/min and introduced through a 0.5 mm diameter port. The local mercury velocity is 0.9 m/s. In this paper, the helium gas flow rate and the local mercury velocity are kept constant for the three cases. Time integration of predicted helium gas volume fraction over time is done to evaluate the gas coverage and calculate the average thickness of the helium gas layer. The predicted time-integrated gas coverage over vertically grooved and horizontally grooved test sections is better than over a smooth wall. The

Creep collapse of thick-walled heat transfer tube subjected to external pressure at high temperature

International Nuclear Information System (INIS)

Ioka, Ikuo; Kaji, Yoshiyuki; Terunuma, Isao; Nekoya, Shin-ichi; Miyamoto, Yoshiaki

1994-09-01

A series of creep collapse tests of thick-walled heat transfer tube were examined experimentally and analytically to confirm an analytical method for creep deformation behavior of a heat transfer tube of an intermediate heat exchanger (IHX) at a depressurization accident of secondary cooling system of HTTR (High Temperature Engineering Test Reactor). The tests were carried out using thick-walled heat transfer tubes made of Hastelloy XR at 950degC in helium gas environment. The predictions of creep collapse time obtained by a general purpose FEM-code ABAQUS were in good agreement with the experimental results. A lot of cracks were observed on the outer surface of the test tubes after the creep collapse. However, the cracks did not pass through the tube wall and, therefore, the leak tightness was maintained regardless of a collapse deformation for all tubes tested. (author)

Gas sensors for ammonia detection based on polyaniline-coated multi-wall carbon nanotubes

International Nuclear Information System (INIS)

He Lifang; Jia Yong; Meng Fanli; Li Minqiang; Liu Jinhuai

2009-01-01

Polyaniline-coated multi-wall carbon nanotubes (PANI-coated MWNTs) were prepared by in situ polymerization method. Field emission scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and thermogravimetric analysis were used to characterize the as-prepared PANI-coated MWNTs. Obtained results indicated that PANI was uniformly coated on MWNTs, and the thickness of the coatings can be controlled by changing the weight ratios of aniline monomer and MWNTs in the polymerization process. Sensors were fabricated by spin-coating onto pre-patterned electrodes, and ammonia gas sensing properties of the as-prepared PANI-coated MWNTs were studied. The results showed a good response and reproducibility towards ammonia at room temperature. In addition, PANI-coated MWNTs exhibited a linear response to ammonia in the range of 0.2-15 ppm. The effects of the thickness of PANI coatings on the gas sensing properties were also investigated in detail. The results suggest a potential application of PANI-coated MWNTs in gas sensor for detecting ammonia.

Method of gas separation

International Nuclear Information System (INIS)

Weltner, W.W.

1980-01-01

In order to separate a mixture of gases having widely different partial pressures at a given temperature, a chamber is employed. A batch of gas mixture is passed into the chamber. The walls of the chamber are cooled by a refrigerant which passes through coils in heat exchange relationship with the walls. By this means the temperature of the chamber is cooled to a temperature (and held at such temperature until equilibrium is reached) at which all the components of the gas mixture have changed state, at least one being solidified and at least one liquefied. The liquid constituents are removed first. Then the chamber is warmed to facilitate removal of the previously solidified constituents. In an example, the gas mixture comprises nitrogen, argon, krypton and xenon, and the walls of the chamber are cooled by liquid nitrogen, the argon and nitrogen being liquefied and the xenon and krypton being solidified. (author)

Stochastic Analysis of Natural Convection in Vertical Channels with Random Wall Temperature

Directory of Open Access Journals (Sweden)

Ryoichi Chiba

2017-01-01

Full Text Available This study attempts to derive the statistics of temperature and velocity fields of laminar natural convection in a heated vertical channel with random wall temperature. The wall temperature is expressed as a random function with respect to time, or a random process. First, analytical solutions of the transient temperature and flow velocity fields for an arbitrary temporal variation in the channel wall temperature are obtained by the integral transform and convolution theorem. Second, the autocorrelations of the temperature and velocity are formed from the solutions, assuming a stationarity in time. The mean square values of temperature and velocity are computed under the condition that the fluctuation in the channel wall temperature can be considered as white noise or a stationary Markov process. Numerical results demonstrate that a decrease in the Prandtl number or an increase in the correlation time of the random process increases the level of mean square velocity but does not change its spatial distribution tendency, which is a bell-shaped profile with a peak at a certain horizontal distance from the channel wall. The peak position is not substantially affected by the Prandtl number or the correlation time.

Numerical investigation of high temperature synthesis gas premixed combustion via ANSYS Fluent

Directory of Open Access Journals (Sweden)

Pashchenko Dmitry

2018-01-01

Full Text Available A numerical model of the synthesis gas pre-mixed combustion is developed. The research was carried out via ANSYS Fluent software. Verification of the numerical results was carried out using experimental data. A visual comparison of the flame contours that obtained by the synthesis gas combustion for Re = 600; 800; 1000 was performed. A comparison of the wall temperature of the combustion chamber, obtained with the help of the developed model, with the results of a physical experiment was also presented. For all cases, good convergence of the results is observed. It is established that a change in the temperature of the syngas/air mixture at the inlet to the combustion chamber does not significantly affect the temperature of the combustion products due to the dissipation of the H2O and CO2 molecules. The obtained results are of practical importance for the design of heat engineering plants with thermochemical heat recovery.

Temperature Gradients on the Cell Wall in the Critical Viscosity Experiment

Science.gov (United States)

Berg, Robert F.; Moldover, Michael R.

1993-01-01

Because of the diverging susceptibility delta rho/delta Tau near the liquid-vapor critical point, temperature gradients must be kept small to maintain adequate sample homogeneity. In our Science Requirements Document we paid particular attention to radial density gradients caused by equilibration of the xenon sample. Axial density gradients were addressed through the requirement that the cell's copper wall have a gradient less than 22 microK/m. This report re-examines the cell wall's temperature distribution in more detail by estimating all known significant contributions to temperature differences on the cell's wall.

Study of flue-gas temperature difference in supercritical once-through boiler

Science.gov (United States)

Kang, Yanchang; Li, Bing; Song, Ang

2018-02-01

The 600 MW coal-fired once-through Boilers with opposed firing at a power plant are found to experience marked temperature variation and even overtemperature on the wall of the heating surface as a result of flue-gas temperature (FGT) variation in the boiler. In this study, operational adjustments were made to the pulverizing, combustion, and secondary air box systems in these boilers, in order to solve problems in internal combustion. The adjustments were found to reduce FGT difference and optimize the boiler’ combustion conditions. The results of this study can provide a reference for optimization of coal-fired boiler of the same type in similar conditions.

Enhancement of NH3 gas sensitivity at room temperature by carbon nanotube-based sensor coated with Co nanoparticles.

Science.gov (United States)

Nguyen, Lich Quang; Phan, Pho Quoc; Duong, Huyen Ngoc; Nguyen, Chien Duc; Nguyen, Lam Huu

2013-01-30

Multi-walled carbon nanotube (MWCNT) film has been fabricated onto Pt-patterned alumina substrates using the chemical vapor deposition method for NH(3) gas sensing applications. The MWCNT-based sensor is sensitive to NH(3) gas at room temperature. Nanoclusters of Co catalysts have been sputtered on the surface of the MWCNT film to enhance gas sensitivity with respect to unfunctionalized CNT films. The gas sensitivity of Co-functionalized MWCNT-based gas sensors is thus significantly improved. The sensor exhibits good repeatability and high selectivity towards NH(3), compared with alcohol and LPG.

High temperature induced disruption of the cell wall integrity and structure in Pleurotus ostreatus mycelia.

Science.gov (United States)

Qiu, Zhiheng; Wu, Xiangli; Gao, Wei; Zhang, Jinxia; Huang, Chenyang

2018-05-30

Fungal cells are surrounded by a tight cell wall to protect them from harmful environmental conditions and to resist lysis. The synthesis and assembly determine the shape, structure, and integrity of the cell wall during the process of mycelial growth and development. High temperature is an important abiotic stress, which affects the synthesis and assembly of cell walls. In the present study, the chitin and β-1,3-glucan concentrations in the cell wall of Pleurotus ostreatus mycelia were changed after high-temperature treatment. Significantly higher chitin and β-1,3-glucan concentrations were detected at 36 °C than those incubated at 28 °C. With the increased temperature, many aberrant chitin deposition patches occurred, and the distribution of chitin in the cell wall was uneven. Moreover, high temperature disrupts the cell wall integrity, and P. ostreatus mycelia became hypersensitive to cell wall-perturbing agents at 36 °C. The cell wall structure tended to shrink or distorted after high temperature. The cell walls were observed to be thicker and looser by using transmission electron microscopy. High temperature can decrease the mannose content in the cell wall and increase the relative cell wall porosity. According to infrared absorption spectrum, high temperature broke or decreased the glycosidic linkages. Finally, P. ostreatus mycelial cell wall was easily degraded by lysing enzymes after high-temperature treatment. In other words, the cell wall destruction caused by high temperature may be a breakthrough for P. ostreatus to be easily infected by Trichoderma.

Wall temperature control of low-speed body drag

Science.gov (United States)

Lin, J. C.; Ash, R. L.

1986-01-01

The use of thermal means to control drag under turbulent boundary layer conditions is examined. Numerical calculations are presented for both skin friction and (unseparated) pressure drag for turbulent boundary-layer flows over a fuselage-like body with wall heat transfer. In addition, thermal control of separation on a bluff body is investigated. It is shown that a total drag reduction of up to 20 percent can be achieved for wall heating with a wall-to-total-freestream temperature ratio of 2. For streamlined slender bodies, partial wall heating of the forebody can produce almost the same order of total drag reduction as the full body heating case. For bluff bodies, the separation delay from partial wall cooling of the afterbody is approximately the same as for the fully cooled body.

Influence of temperature on current-induced domain wall motion and its Walker breakdown

International Nuclear Information System (INIS)

Fan, Lvchao; Hu, Jingguo; Su, Yuanchang; Zhu, Jinrong

2016-01-01

The current-driven domain wall propagation along a thin ferromagnetic strip with thermal field is studied by means of micromagnetic simulations. The results show that the velocity of domain wall is almost independent of temperature until Walker breakdown happened. However the thermal field can suppress Walker breakdown and makes domain wall move faster. Further analysis indicates that the thermal field tends to keep the out-of-plane magnetic moment of the domain wall stay in high value, which can promote domain wall motion and suppress the Walker breakdown by breaking the period of domain wall transformation. - Highlights: • Influences of temperature on the displacement and the velocity of DW are shown. • The suppression of Walker breakdown by temperature is given. • The reason for suppressing Walker breakdown is analyzed. • The breaking transformation period of Walker breakdown by temperature is given.

Temperature of gas delivered from ventilators.

Science.gov (United States)

Chikata, Yusuke; Onodera, Mutsuo; Imanaka, Hideaki; Nishimura, Masaji

2013-01-01

Although heated humidifiers (HHs) are the most efficient humidifying device for mechanical ventilation, some HHs do not provide sufficient humidification when the inlet temperature to the water chamber is high. Because portable and home-care ventilators use turbines, blowers, pistons, or compressors to inhale in ambient air, they may have higher gas temperature than ventilators with piping systems. We carried out a bench study to investigate the temperature of gas delivered from portable and home-care ventilators, including the effects of distance from ventilator outlet, fraction of inspiratory oxygen (FIO2), and minute volume (MV). We evaluated five ventilators equipped with turbine, blower, piston, or compressor system. Ambient air temperature was adjusted to 24°C ± 0.5°C, and ventilation was set at FIO2 0.21, 0.6, and 1.0, at MV 5 and 10 L/min. We analyzed gas temperature at 0, 40, 80, and 120 cm from ventilator outlet and altered ventilator settings. While temperature varied according to ventilators, the outlet gas temperature of ventilators became stable after, at the most, 5 h. Gas temperature was 34.3°C ± 3.9°C at the ventilator outlet, 29.5°C ± 2.2°C after 40 cm, 25.4°C ± 1.2°C after 80 cm and 25.1°C ± 1.2°C after 120 cm (P < 0.01). FIO2 and MV did not affect gas temperature. Gas delivered from portable and home-care ventilator was not too hot to induce heated humidifier malfunctioning. Gas soon declined when passing through the limb.

Interaction of chemical reactions and radiant heat transfer with temperature turbulent pulsations and its effect on heat traner in high-temperature gas flows

International Nuclear Information System (INIS)

Petukhov, B.S.; Zal'tsman, I.G.; Shikov, V.K.

1980-01-01

Methods of taking account of mutual effect of chemical transformations, radiation and turbulence in the calculations of heat transfer in gas flows are considered. Exponential functions of medium parameters are used to describe chemical sources and optical properties of media. It is shown using as an example the dissociation reaction C 2 reversible 2C that the effect of temperature and composition pulsations on recombination rates is negligibly small. It is also shown on the example of turbulent flow of hot molecular gas in a flat channel with cold walls that at moderate temperatures the effect of temperature pulsations on heat radiation flow can be significant (30-40%). The calculational results also show that there is a region in a turbulent boundary layer where the radiation greatly affects the coefficient of turbulent heat transfer

Sensing of low concentration of ammonia at room temperature by decorated multi-walled carbon nanotube: fabrication and characteristics

Science.gov (United States)

Hasnahena, S. T.; Roy, M.

2018-01-01

A chemical sensor based on multi-walled carbon nanotube (MWCNT) decorated with densely populated thiol-capped gold nanoparticles (AuNPs) with sizes smaller than 3 nm for sensing low concentrations of ammonia gas is reported. The functionalized MWCNTs, subsequently decorated with AuNPs following an easy fabrication route were exposed to NH3 gas at the room temperature and the electrical resistance of the sensor changed upon exposure. The sensor also partially recovered the initial state after sensing in the normal air environment (without any dry air or N2 gas purge). The gold nanoparticles decoration is found to enhance the sensitivity and selectivity of MWCNT towards NH3 gas under ambient conditions with a reduced response and recovery time. The material was structurally characterized by Transmission Electron Microscopy and X-ray Photoelectron Spectroscopy. Thermal stability of the sensor till 574 °C was demonstrated by TGA analysis. This papers describes how thiol-capped AuNPs are uniformly decorated on the outer walls of the MWCNTs with a separation of 2-3 nm making use of the ionic nature of Au and how this uniform distribution of AuNPs increases the active sites for absorption of NH3 gas molecules leading to sensing its low concentrations.

Study on thermodynamic cycle of high temperature gas-cooled reactor

International Nuclear Information System (INIS)

Qu Xinhe; Yang Xiaoyong; Wang Jie

2017-01-01

The development trend of the (very) High temperature gas-cooled reactor is to gradually increase the reactor outlet temperature. The different power conversion units are required at the different reactor outlet temperature. In this paper, for the helium turbine direct cycle and the combined cycle of the power conversion unit of the High temperature gas-cooled reactor, the mathematic models are established, and three cycle plans are designed. The helium turbine direct cycle is a Brayton cycle with recuperator, precooler and intercooler. In the combined cycle plan 1, the topping cycle is a simple Brayton cycle without recuperator, precooler and intercooler, and the bottoming cycle is based on the steam parameters (540deg, 6 MPa) recommended by Siemens. In the combined cycle plan 2, the topping cycle also is a simple Brayton cycle, and the bottoming cycle which is a Rankine cycle with reheating cycle is based on the steam parameters of conventional subcritical thermal power generation (540degC, 18 MPa). The optimization results showed that the cycle efficiency of the combined cycle plan 2 is the highest, the second is the helium turbine direct cycle, and the combined cycle plan 2 is the lowest. When the reactor outlet temperature is 900degC and the pressure ratio is 2.02, the cycle efficiency of the combined cycle plan 2 can reach 49.7%. The helium turbine direct cycle has a reactor inlet temperature above 500degC due to the regenerating cycle, so it requires a cooling circuit for the internal wall of the reactor pressure vessel. When the reactor outlet temperature increases, the increase of the pressure ratio required by the helium turbine direct cycle increases may bring some difficulties to the design and manufacture of the magnetic bearings. For the combined cycle, the reactor inlet temperature can be controlled below than 370degC, so the reactor pressure vessel can use SA533 steel without cooling the internal wall of the reactor pressure vessel. The pressure

Characteristics of compressed natural gas jet and jet-wall impingement using the Schlieren imaging technique

International Nuclear Information System (INIS)

Ismael, M A; Heikal, M R; Baharom, M B

2013-01-01

An experimental study was performed to investigate the compressed natural gas jet characteristics and jet-wall impingement using the Schlieren imaging technique and image processing. An injector driver was used to drive the natural gas injector and synchronized with camera triggering. A constant-volume optical chamber was designed to facilitate maximum optical access for the study of the jet macroscopic characteristics and jet-wall impingement at different injection pressures and injectors-wall distances. Measurement of the jet tip penetration and cone angle at different conditions are presented in this paper together with temporal presentation of the jet radial travel along the wall.

Improving methane gas sensing properties of multi-walled carbonnanotubes by vanadium oxide filling

CSIR Research Space (South Africa)

Chimowa, George

2017-08-01

Full Text Available Manipulation of electrical properties and hence gas sensing properties of multi-walled carbon nanotubes (MWNTs) by filling the inner wall with vanadium oxide is presented. Using a simple capillary technique, MWNTs are filled with vanadium metal...

Enhancement of NH3 Gas Sensitivity at Room Temperature by Carbon Nanotube-Based Sensor Coated with Co Nanoparticles

Directory of Open Access Journals (Sweden)

Lich Quang Nguyen

2013-01-01

Full Text Available Multi-walled carbon nanotube (MWCNT film has been fabricated onto Pt-patterned alumina substrates using the chemical vapor deposition method for NH3 gas sensing applications. The MWCNT-based sensor is sensitive to NH3 gas at room temperature. Nanoclusters of Co catalysts have been sputtered on the surface of the MWCNT film to enhance gas sensitivity with respect to unfunctionalized CNT films. The gas sensitivity of Co-functionalized MWCNT-based gas sensors is thus significantly improved. The sensor exhibits good repeatability and high selectivity towards NH3, compared with alcohol and LPG.

Temperature fluctuations in fully-developed turbulent channel flow with heated upper wall

Science.gov (United States)

Bahri, Carla; Mueller, Michael; Hultmark, Marcus

2013-11-01

The interactions and scaling differences between the velocity field and temperature field in a wall-bounded turbulent flow are investigated. In particular, a fully developed turbulent channel flow perturbed by a step change in the wall temperature is considered with a focus on the details of the developing thermal boundary layer. For this specific study, temperature acts as a passive scalar, having no dynamical effect on the flow. A combination of experimental investigation and direct numerical simulation (DNS) is presented. Velocity and temperature data are acquired with high accuracy where, the flow is allowed to reach a fully-developed state before encountering a heated upper wall at constant temperature. The experimental data is compared with DNS data where simulations of the same configuration are conducted.

Gas leak tightness of SiC/SiC composites at elevated temperature

Energy Technology Data Exchange (ETDEWEB)

Hayasaka, Daisuke, E-mail: hayasaka@oasis.muroran-it.ac.jp [OASIS, Muroran Institute of Technology, Muroran, Hokkaido (Japan); Graduate School of Engineering, Muroran Institute of Technology, Muroran, Hokkaido (Japan); Park, Joon-Soo. [OASIS, Muroran Institute of Technology, Muroran, Hokkaido (Japan); Kishimoto, Hirotatsu [OASIS, Muroran Institute of Technology, Muroran, Hokkaido (Japan); Graduate School of Engineering, Muroran Institute of Technology, Muroran, Hokkaido (Japan); Kohyama, Akira [OASIS, Muroran Institute of Technology, Muroran, Hokkaido (Japan)

2016-11-01

Highlights: • NITE-SiC/SiC has extremely densified microstructure compared with other SiC/SiC composite like CVI. • Excellent helium and hydrogen gas-leak tightness of SiC/SiC composites by DEMO-NITE method from prototype industrialization production line was presented. • The excellence against stainless steel and Zircaloy at elevated temperature, together with generic excellent properties of SiC will be inevitable for innovative blanket and divertors for DEMO- and power- fusion reactors. - Abstract: SiC/SiC composite materials are attractive candidates for high heat flux components and blanket of fusion reactor, mainly due to their high temperature properties, radiation damage tolerance and low induced radioactivity. One of the challenges for SiC/SiC application in fusion reactors is to satisfy sufficient gas leak tightness of hydrogen and helium isotopes. Although many efforts have been carried-out, SiC/SiC composites by conventional processes have not been successful to satisfy the requirements, except SiC/SiC composites by NITE-methods. Toward the early realization of SiC/SiC components into fusion reactor systems process development of NITE-process has been continued. Followed to the brief introduction of recently developed DEMO-NITE process, baseline properties and hydrogen and helium gas leak tightness is presented. SiC/SiC claddings with 10 mm in diameter and 1 mm in wall thickness are tested by gas leak tightness system developed. The leak tightness measurements are done room temperature to 400 °C. Excellent gas leak tightness equivalent or superior to Zircaloy claddings for light water fission reactors is confirmed. The excellent gas leak tightness suggests nearly perfect suppression of large gas leak path in DEMO-NITE SiC/SiC.

An investigation on near wall transport characteristics in an adiabatic upward gas-liquid two-phase slug flow

Science.gov (United States)

Zheng, Donghong; Che, Defu

2007-08-01

The near-wall transport characteristics, inclusive of mass transfer coefficient and wall shear stress, which have a great effect on gas-liquid two-phase flow induced internal corrosion of low alloy pipelines in vertical upward oil and gas mixing transport, have been both mechanistically and experimentally investigated in this paper. Based on the analyses on the hydrodynamic characteristics of an upward slug unit, the mass transfer in the near wall can be divided into four zones, Taylor bubble nose zone, falling liquid film zone, Taylor bubble wake zone and the remaining liquid slug zone; the wall shear stress can be divided into two zones, the positive wall shear stress zone associated with the falling liquid film and the negative wall shear stress zone associated with the liquid slug. Based on the conventional mass transfer and wall shear stress characteristics formulas of single phase liquid full-pipe turbulent flow, corrected normalized mass transfer coefficient formula and wall shear stress formula are proposed. The calculated results are in good agreement with the experimental data. The shear stress and the mass transfer coefficient in the near wall zone are increased with the increase of superficial gas velocity and decreased with the increase of superficial liquid velocity. The mass transfer coefficients in the falling liquid film zone and the wake zone of leading Taylor bubble are lager than those in the Taylor bubble nose zone and the remaining liquid slug zone, and the wall shear stress associated falling liquid film is larger than that associated the liquid slug. The mass transfer coefficient is within 10-3 m/s, and the wall shear stress below 103 Pa. It can be concluded that the alternate wall shear stress due to upward gas-liquid slug flow is considered to be the major cause of the corrosion production film fatigue cracking.

RCCS Experiments and Validation for High Temperature Gas-Cooled Reactor

International Nuclear Information System (INIS)

Chang Oh; Cliff Davis; Goon C. Park

2007-01-01

A reactor cavity cooling system (RCCS), an air-cooled helical coil RCCS unit immersed in the water pool, was proposed to overcome the disadvantages of the weak cooling ability of air-cooled RCCS and the complex structure of water-cooled RCCS for the high temperature gas-cooled reactor (HTGR). An experimental apparatus was constructed to investigate the various heat transfer phenomena in the water pool type RCCS, such as the natural convection of air inside the cavity, radiation in the cavity, the natural convection of water in the water pool and the forced convection of air in the cooling pipe. The RCCS experimental results were compared with published correlations. The CFX code was validated using data from the air-cooled portion of the RCCS. The RELAP5 code was validated using measured temperatures from the reactor vessel and cavity walls

Wall deffects in field theories at finite temperature

International Nuclear Information System (INIS)

Bazeia Filho, D.

1985-01-01

We discuss the effect of restauration of simmetry in field theories at finite temperature and its relation with wall deffects which appear as consequence of the instability of the constant field configuration. (M.W.O.) [pt

Temperature-gradient instability induced by conducting end walls

International Nuclear Information System (INIS)

Berk, H.L.; Ryutov, D.D.; Tsidulko, Yu.A.

1990-04-01

A new rapidly growing electron temperature gradient instability is found for a plasma in contact with a conducting wall. The linear instability analysis is presented and speculations are given for its nonlinear consequences. This instability illustrates that conducting walls can produce effects that are detrimental to plasma confinement. This mode should be of importance in open-ended systems including astrophysical plasmas, mirror machines and at the edge of tokamaks where field lines are open and are connected to limiters or divertors. 16 refs., 2 figs

First wall fusion blanket temperature variation - slab geometry

International Nuclear Information System (INIS)

Fillo, J.A.

1978-01-01

The first wall of a fusion blanket is approximated by a slab, with the surface facing the plasma subjected to an applied heat flux, while the rear surface is convectively cooled. The relevant parameters affecting the heat transfer during the early phases of heating as well as for large times are established. Analytical solutions for the temperature variation with time and space are derived. Numerical calculations for an aluminum and stainless steel slab are performed for a wall loading of 1 MW(th)/m 2 . Both helium and water cooling are considered. (Auth.)

Startup analysis for a high temperature gas loaded heat pipe

Science.gov (United States)

Sockol, P. M.

1973-01-01

A model for the rapid startup of a high-temperature gas-loaded heat pipe is presented. A two-dimensional diffusion analysis is used to determine the rate of energy transport by the vapor between the hot and cold zones of the pipe. The vapor transport rate is then incorporated in a simple thermal model of the startup of a radiation-cooled heat pipe. Numerical results for an argon-lithium system show that radial diffusion to the cold wall can produce large vapor flow rates during a rapid startup. The results also show that startup is not initiated until the vapor pressure p sub v in the hot zone reaches a precise value proportional to the initial gas pressure p sub i. Through proper choice of p sub i, startup can be delayed until p sub v is large enough to support a heat-transfer rate sufficient to overcome a thermal load on the heat pipe.

Experimental demonstration of a tailored-width microchannel heat exchanger configuration for uniform wall temperature

International Nuclear Information System (INIS)

Riera, S; Barrau, J; Rosell, J I; Omri, M; Fréchette, L G

2013-01-01

In this work, an experimental study of a novel microfabricated heat sink configuration that tends to uniform the wall temperature, even with increasing flow temperature, is presented. The design consists of a series of microchannel sections with stepwise varying width. This scheme counteracts the flow temperature increase by reducing the local thermal resistance along the flow path. A test apparatus with uniform heat flux and distributed wall temperature measurements was developed for microchannel heat exchanger characterisation. The energy balance is checked and the temperature distribution is analysed for each test. The results show that the wall temperature decreases slightly along the flow path while the fluid temperature increases, highlighting the strong impact of this approach. For a flow rate of 16 ml/s, the mean thermal resistance of the heat sink is 2,35·10 −5 m 2 ·K/W which enhances the results compared to the millimeter scale channels nearly three-fold. For the same flow rate and a heat flux of 50 W/cm 2 , the temperature uniformity, expressed as the standard deviation of the wall temperature, is around 6 °C

Effects of gas-wall partitioning in Teflon tubing and instrumentation on time-resolved measurements of gas-phase organic compounds

Science.gov (United States)

Pagonis, Demetrios; Krechmer, Jordan E.; de Gouw, Joost; Jimenez, Jose L.; Ziemann, Paul J.

2017-12-01

Recent studies have demonstrated that organic compounds can partition from the gas phase to the walls in Teflon environmental chambers and that the process can be modeled as absorptive partitioning. Here these studies were extended to investigate gas-wall partitioning of organic compounds in Teflon tubing and inside a proton-transfer-reaction mass spectrometer (PTR-MS) used to monitor compound concentrations. Rapid partitioning of C8-C14 2-ketones and C11-C16 1-alkenes was observed for compounds with saturation concentrations (c∗) in the range of 3 × 104 to 1 × 107 µg m-3, causing delays in instrument response to step-function changes in the concentration of compounds being measured. These delays vary proportionally with tubing length and diameter and inversely with flow rate and c∗. The gas-wall partitioning process that occurs in tubing is similar to what occurs in a gas chromatography column, and the measured delay times (analogous to retention times) were accurately described using a linear chromatography model where the walls were treated as an equivalent absorbing mass that is consistent with values determined for Teflon environmental chambers. The effect of PTR-MS surfaces on delay times was also quantified and incorporated into the model. The model predicts delays of an hour or more for semivolatile compounds measured under commonly employed conditions. These results and the model can enable better quantitative design of sampling systems, in particular when fast response is needed, such as for rapid transients, aircraft, or eddy covariance measurements. They may also allow estimation of c∗ values for unidentified organic compounds detected by mass spectrometry and could be employed to introduce differences in time series of compounds for use with factor analysis methods. Best practices are suggested for sampling organic compounds through Teflon tubing.

The effects of chemical kinetics and wall temperature on performance of porous media burners

Science.gov (United States)

mohammadi, Iman; Hossainpour, Siamak

2013-06-01

This paper reports a two-dimensional numerical prediction of premixed methane-air combustion in inert porous media burner by using of four multi-step mechanisms: GRI-3.0 mechanism, GRI-2.11 mechanism and the skeletal and 17 Species mechanisms. The effects of these models on temperature, chemical species and pollutant emissions are studied. A two-dimensional axisymmetric model for premixed methane-air combustion in porous media burner has developed. The finite volume method has used to solve the governing equations of methane-air combustion in inert porous media burner. The results indicate that the present four models have the same accuracy in predicting temperature profiles and the difference between these profiles is not more than 2 %. In addition, the Gri-3.0 mechanism shows the best prediction of NO emission in comparison with experimental data. The 17 Species mechanism shows good agreement in prediction of temperature and pollutant emissions with GRI-3.0, GRI-2.11 and the skeletal mechanisms. Also the effects of wall temperature on the gas temperature and mass fraction of species such as NO and CH4 are studied.

Gas leakage rate through reinforced concrete shear walls: Numerical study

International Nuclear Information System (INIS)

Wang Ting; Hutchinson, Tara C.

2005-01-01

Unlined reinforced concrete shear walls are often used as 'tertiary boundaries' in the United States Department of Energy (DOE) to house dangerous gases. An unanticipated event, such as an earthquake, may cause gases stored inside the walls to disperse into the environment resulting in excess pollution. To address this concern, in this paper, a methodology to numerically predict the gas leakage rate through these shear walls under lateral loading conditions is proposed. This methodology involves finite element and flow rate analysis. Strain distributions are obtained from the finite element analysis, and then used to simulate the crack characteristics on the concrete specimen. The flow rate through the damaged concrete specimen is then estimated using flow rate formulas available from the literature. Results from an experimental specimen are used to evaluate the methodology, and particularly its robustness in the flow rate estimation

Gas Temperature Measurement in a Glow Discharge Plasma

Science.gov (United States)

Sloneker, Kenneth; Podder, Nirmol; McCurdy, William E.; Shi, Shi

2009-10-01

In this study a relatively inexpensive quartz protected thermocouple is used to measure the gas temperature in the positive column of a glow discharge plasma. For simplicity a K-type thermocouple is used to interpret the gas temperature from the sensor voltage at pressures from 0.5 Torr to 15 Torr and discharge currents from 5 mA to 120 mA. Gas temperature is investigated as a function of the gas pressure at fixed discharge currents and as a function of discharge current at fixed gas pressures in three different gas species (Ar, N2, and He). An infinite cylinder model is used to compute the average gas temperature of the discharge from joule heating and gas thermal conductivity. The model and measurement data agree within 1% to 10% depending on plasma parameters. Data for all three gases have a similar quasi-linear increasing error as compared to the model.

Medium temperature carbon dioxide gas turbine reactor

International Nuclear Information System (INIS)

Kato, Yasuyoshi; Nitawaki, Takeshi; Muto, Yasushi

2004-01-01

A carbon dioxide (CO 2 ) gas turbine reactor with a partial pre-cooling cycle attains comparable cycle efficiencies of 45.8% at medium temperature of 650 deg. C and pressure of 7 MPa with a typical helium (He) gas turbine reactor of GT-MHR (47.7%) at high temperature of 850 deg. C. This higher efficiency is ascribed to: reduced compression work around the critical point of CO 2 ; and consideration of variation in CO 2 specific heat at constant pressure, C p , with pressure and temperature into cycle configuration. Lowering temperature to 650 deg. C provides flexibility in choosing materials and eases maintenance through the lower diffusion leak rate of fission products from coated particle fuel by about two orders of magnitude. At medium temperature of 650 deg. C, less expensive corrosion resistant materials such as type 316 stainless steel are applicable and their performance in CO 2 have been proven during extensive operation in AGRs. In the previous study, the CO 2 cycle gas turbomachinery weight was estimated to be about one-fifth compared with He cycles. The proposed medium temperature CO 2 gas turbine reactor is expected to be an alternative solution to current high-temperature He gas turbine reactors

Near-wall effects in rarefied gas micro-flows: some modern hydrodynamic approaches

International Nuclear Information System (INIS)

O'Hare, Lynne; Lockerby, Duncan A.; Reese, Jason M.; Emerson, David R.

2007-01-01

Methods for simulating the critical near-wall region in hydrodynamic models of gas micro-flows are discussed. Two important non-equilibrium flow features - velocity slip at solid walls, and the Knudsen layer (which extends one or two molecular mean free paths into the gas from a surface) - are investigated using different modelling approaches. In addition to a discussion of Maxwell's slip boundary condition, a newly implemented 'wall-function' model that has been developed to improve hydrodynamic simulations of the Knudsen layer is described. Phenomenological methods are compared to physical modelling and it is shown that, while both simulation types have merit, and both can quantitatively improve results in most cases, there are drawbacks associated with each approach. Phenomenological techniques, for example, may not be sufficiently general, whilst issues with applicability and stability are known to exist in some physical models. It is concluded that, at present, neither approach is unambiguously preferable to the other, and that both physical and phenomenological modelling should be the subject of future work

Structure of Temperature Field on a Wall in Turbulent Flow (Statistics of Thermal Streaks, Heat Transfer)

International Nuclear Information System (INIS)

Hetsroni, G.; Mosyak, A.; Rozenblit, R.; Yarin, L.P.

1998-01-01

The present work deals with an experimental study of a temperature field on the wall in turbulent flow. The measurements of the local, instantaneous and average temperature of the wall were carried out by the hot-foil infrared technique. The detailed data on the average and fluctuation temperature distributions are presented. It is shown that temperature fluctuations, as normalized by the difference between the temperatures of the undisturbed fluid and the wall, do not change

Numerical simulation of gas-phonon coupling in thermal transpiration flows.

Science.gov (United States)

Guo, Xiaohui; Singh, Dhruv; Murthy, Jayathi; Alexeenko, Alina A

2009-10-01

Thermal transpiration is a rarefied gas flow driven by a wall temperature gradient and is a promising mechanism for gas pumping without moving parts, known as the Knudsen pump. Obtaining temperature measurements along capillary walls in a Knudsen pump is difficult due to extremely small length scales. Meanwhile, simplified analytical models are not applicable under the practical operating conditions of a thermal transpiration device, where the gas flow is in the transitional rarefied regime. Here, we present a coupled gas-phonon heat transfer and flow model to study a closed thermal transpiration system. Discretized Boltzmann equations are solved for molecular transport in the gas phase and phonon transport in the solid. The wall temperature distribution is the direct result of the interfacial coupling based on mass conservation and energy balance at gas-solid interfaces and is not specified a priori unlike in the previous modeling efforts. Capillary length scales of the order of phonon mean free path result in a smaller temperature gradient along the transpiration channel as compared to that predicted by the continuum solid-phase heat transfer. The effects of governing parameters such as thermal gradients, capillary geometry, gas and phonon Knudsen numbers and, gas-surface interaction parameters on the efficiency of thermal transpiration are investigated in light of the coupled model.

Overview of the JET results with the ITER-like wall

Science.gov (United States)

Romanelli, F.; EFDA Contributors, JET

2013-10-01

Following the completion in May 2011 of the shutdown for the installation of the beryllium wall and the tungsten divertor, the first set of JET campaigns have addressed the investigation of the retention properties and the development of operational scenarios with the new plasma-facing materials. The large reduction in the carbon content (more than a factor ten) led to a much lower Zeff (1.2-1.4) during L- and H-mode plasmas, and radiation during the burn-through phase of the plasma initiation with the consequence that breakdown failures are almost absent. Gas balance experiments have shown that the fuel retention rate with the new wall is substantially reduced with respect to the C wall. The re-establishment of the baseline H-mode and hybrid scenarios compatible with the new wall has required an optimization of the control of metallic impurity sources and heat loads. Stable type-I ELMy H-mode regimes with H98,y2 close to 1 and βN ˜ 1.6 have been achieved using gas injection. ELM frequency is a key factor for the control of the metallic impurity accumulation. Pedestal temperatures tend to be lower with the new wall, leading to reduced confinement, but nitrogen seeding restores high pedestal temperatures and confinement. Compared with the carbon wall, major disruptions with the new wall show a lower radiated power and a slower current quench. The higher heat loads on Be wall plasma-facing components due to lower radiation made the routine use of massive gas injection for disruption mitigation essential.

Overview of the JET results with the ITER-like wall

International Nuclear Information System (INIS)

Romanelli, F.

2013-01-01

Following the completion in May 2011 of the shutdown for the installation of the beryllium wall and the tungsten divertor, the first set of JET campaigns have addressed the investigation of the retention properties and the development of operational scenarios with the new plasma-facing materials. The large reduction in the carbon content (more than a factor ten) led to a much lower Z eff (1.2–1.4) during L- and H-mode plasmas, and radiation during the burn-through phase of the plasma initiation with the consequence that breakdown failures are almost absent. Gas balance experiments have shown that the fuel retention rate with the new wall is substantially reduced with respect to the C wall. The re-establishment of the baseline H-mode and hybrid scenarios compatible with the new wall has required an optimization of the control of metallic impurity sources and heat loads. Stable type-I ELMy H-mode regimes with H 98,y2 close to 1 and β N ∼ 1.6 have been achieved using gas injection. ELM frequency is a key factor for the control of the metallic impurity accumulation. Pedestal temperatures tend to be lower with the new wall, leading to reduced confinement, but nitrogen seeding restores high pedestal temperatures and confinement. Compared with the carbon wall, major disruptions with the new wall show a lower radiated power and a slower current quench. The higher heat loads on Be wall plasma-facing components due to lower radiation made the routine use of massive gas injection for disruption mitigation essential. (paper)

Ceramic gas turbine shroud

Science.gov (United States)

Shi, Jun; Green, Kevin E.

2014-07-22

An example gas turbine engine shroud includes a first annular ceramic wall having an inner side for resisting high temperature turbine engine gasses and an outer side with a plurality of radial slots. A second annular metallic wall is positioned radially outwardly of and enclosing the first annular ceramic wall and has a plurality of tabs in communication with the slot of the first annular ceramic wall. The tabs of the second annular metallic wall and slots of the first annular ceramic wall are in communication such that the first annular ceramic wall and second annular metallic wall are affixed.

On the Goertler instability in hypersonic flows: Sutherland law fluids and real gas effects

Science.gov (United States)

Fu, Yibin B.; Hall, Philip; Blackaby, Nicholas D.

1990-01-01

The Goertler vortex instability mechanism in a hypersonic boundary layer on a curved wall is investigated. The precise roles of the effects of boundary layer growth, wall cooling, and gas dissociation is clarified in the determination of stability properties. It is first assumed that the fluid is an ideal gas with viscosity given by Sutherland's law. It is shown that when the free stream Mach number M is large, the boundary layer divides into two sublayers: a wall layer of O(M sup 3/2) thickness over which the basic state temperature is O(M squared) and a temperature adjustment layer of O(1) thickness over which the basic state temperature decreases monotonically to its free stream value. Goertler vortices which have wavelengths comparable with the boundary layer thickness are referred to as wall modes. It is shown that their downstream evolution is governed by a set of parabolic partial differential equations and that they have the usual features of Goertler vortices in incompressible boundary layers. As the local wavenumber increases, the neutral Goertler number decreases and the center of vortex activity moves towards the temperature adjustment layer. Goertler vortices with wavenumbers of order one or larger must necessarily be trapped in the temperature adjustment layer and it is this mode which is most dangerous. For this mode, it was found that the leading order term in the Goertler number expansion is independent of the wavenumber and is due to the curvature of the basic state. This term is also the asymptotic limit of the neutral Goertler numbers of the wall mode. To determine the higher order corrections terms in the Goertler number expansion, two wall curvature cases are distinguished. Real gas effects were investigated by assuming that the fluid is an ideal dissociating gas. It was found that both gas dissociation and wall cooling are destabilizing for the mode trapped in the temperature adjustment layer, but for the wall mode trapped near the wall the

Temperature measurements in a wall stabilized steady flame using CARS

KAUST Repository

Sesha Giri, Krishna; Lacoste, Deanna; Damazo, Jason; Kwon, Eddie; Roberts, William L.

2017-01-01

-Stokes Raman Scattering (CARS) thermometry as close as 275 μm to a convex wall cooled with water has been carried out. The standard deviation of mean temperatures is observed to be ~6.5% for high temperatures (>2000K) and ~14% in the lower range (<500K

Gas temperature of capacitance spark discharge in air

International Nuclear Information System (INIS)

Ono, Ryo; Nifuku, Masaharu; Fujiwara, Shuzo; Horiguchi, Sadashige; Oda, Tetsuji

2005-01-01

Capacitance spark discharge has been widely used for studying the ignition of flammable gas caused by electrostatic discharge. In the present study, the gas temperature of capacitance spark discharge is measured. The gas temperature is an important factor in understanding the electrostatic ignition process because it influences the reaction rate of ignition. Spark discharge is generated in air with a pulse duration shorter than 100 ns. The discharge energy is set to 0.03-1 mJ. The rotational and vibrational temperatures of the N 2 molecule are measured using the emission spectrum of the N 2 second positive system. The rotational and vibrational temperatures are estimated to be 500 and 5000 K, respectively, which are independent of the discharge energy. This result indicates that most of the electron energy is consumed in the excitation of vibrational levels of molecules rather than the heating of the gas. The gas temperature after discharge is also measured by laser-induced fluorescence of OH radicals. It is shown that the gas temperature increases after discharge and reaches approximately 1000 K at 3 μs after discharge. Then the temperature decreases at a rate in the range of 8-35 K/μs depending on the discharge energy

Effects of reducing temperatures on the hydrogen storage capacity of double-walled carbon nanotubes with Pd loading.

Science.gov (United States)

Sheng, Qu; Wu, Huimin; Wexler, David; Liu, Huakun

2014-06-01

The effects of different temperatures on the hydrogen sorption characteristics of double-walled carbon nanotubes (DWCNTs) with palladium loading have been investigated. When we use different temperatures, the particle sizes and specific surface areas of the samples are different, which affects the hydrogen storage capacity of the DWCNTs. In this work, the amount of hydrogen storage capacity was determined (by AMC Gas Reactor Controller) to be 1.70, 1.85, 2.00, and 1.93 wt% for pristine DWCNTS and for 2%Pd/DWCNTs-300 degrees C, 2%Pd/DWCNTs-400 degrees C, and 2%Pd/DWCNTs-500 degrees C, respectively. We found that the hydrogen storage capacity can be enhanced by loading with 2% Pd nanoparticles and selecting a suitable temperature. Furthermore, the sorption can be attributed to the chemical reaction between atomic hydrogen and the dangling bonds of the DWCNTs.

Characteristics of turbulent velocity and temperature in a wall channel of a heated rod bundle

Energy Technology Data Exchange (ETDEWEB)

Krauss, T.; Meyer, L. [Forschungszentrum Karlsruhe (Germany)

1995-09-01

Turbulent air flow in a wall sub-channel of a heated 37-rod bundle (P/D = 1.12, W/D = 1.06) was investigated. measurements were performed with hot-wire probe with X-wires and a temperature wire. The mean velocity, the mean fluid temperature, the wall shear stress and wall temperature, the turbulent quantities such as the turbulent kinetic energy, the Reynolds-stresses and the turbulent heat fluxes were measured and are discussed with respect to data from isothermal flow in a wall channel and heated flow in a central channel of the same rod bundle. Also, data on the power spectral densities of the velocity and temperature fluctuations are presented. These data show the existence of large scale periodic fluctuations are responsible for the high intersubchannel heat and momentum exchange.

The effect of water vapor in the reactor cavity in a MHTGR [Modular High Temperature Gas Cooled Reactor] on the radiation heat transfer

International Nuclear Information System (INIS)

Cappiello, M.W.

1991-01-01

Analyses have been completed to determine the effect of the presence of water vapor in the reactor cavity in a modular high temperature gas cooled reactor on the predicted radiation heat transfer from the vessel wall to the reactor cavity cooling system. The analysis involves the radiation heat transfer between two parallel plates with an absorbing and emitting medium present. Because the absorption in the water vapor is spectrally dependent, the solution is difficult even for simple geometries. A computer code was written to solve the problem using the Monte Carlo method. The code was validated against closed form solutions, and shows excellent agreement. In the analysis of the reactor problem, the results show that the reduction in heat transfer, and the consequent increase in the vessel wall temperature, can be significant. This effect can be cast in terms of a reduction in the wall surface emissivities from 0.8 to 0.59. Because of the insulating effect of the water vapor, increasing the gap distance between the vessel wall and the cooling system will cause the vessel wall temperature to increase further. Care should be taken in the design of the facility to minimize the gap distance and keep temperature increase within allowable limits. 3 refs., 6 figs., 4 tabs

Flow characteristics of helium gas going through a 90°elbow for flow measurement

International Nuclear Information System (INIS)

Feng Beibei; Wang Shiming; Yang Xingtuan; Jiang Shengyao

2014-01-01

Numerical simulation is performed to investigate the pressure distribution of He-gas under high pressure and high temperature for 10MW High Temperature Gas-cooled Reactor (HTGR-10). Experimental measurements of wall pressure through a self-built test system are carried out to validate the credibility of the computational approach. We present a study for complex flow structure of He-gas using the case of an structurally 90°elbow that is reconstructed from the steam generator of HTGR-10. Pressure measurement of inner wall and outer wall is used to compare with the numerical results. Distribution of wall pressure of He-gas flowing through 90° elbow based on the numerical and experimental approaches show good agreement. Wall pressure distribution of eight cross sections of the elbow is given in detail to represent the entire region of elbow. (author)

Modeling of gas-phase chemistry in the chemical vapor deposition of polysilicon in a cold wall system

Energy Technology Data Exchange (ETDEWEB)

Toprac, A.J.; Edgar, T.F.; Trachtenberg, I. (Univ. of Texas, Austin, TX (United States). Dept. of Chemical Engineering)

1993-06-01

The relative contribution of gas-phase chemistry to deposition processes is an important issue both from the standpoint of operation and modeling of these processes. In polysilicon deposition from thermally activated silane in a cold wall rapid thermal chemical vapor deposition (RTCVD) system, the relative contribution of gas-phase chemistry to the overall deposition rate was examined by a mass-balance model. Evaluating the process at conditions examined experimentally, the model indicated that gas-phase reactions may be neglected to good accuracy in predicting polysilicon deposition rate. The model also provided estimates of the level of gas-phase generated SiH[sub 2] associated with deposition on the cold-process chamber walls.

Molecular beam mass spectrometer equipped with a catalytic wall reactor for in situ studies in high temperature catalysis research

International Nuclear Information System (INIS)

Horn, R.; Ihmann, K.; Ihmann, J.; Jentoft, F.C.; Geske, M.; Taha, A.; Pelzer, K.; Schloegl, R.

2006-01-01

A newly developed apparatus combining a molecular beam mass spectrometer and a catalytic wall reactor is described. The setup has been developed for in situ studies of high temperature catalytic reactions (>1000 deg. C), which involve besides surface reactions also gas phase reactions in their mechanism. The goal is to identify gas phase radicals by threshold ionization. A tubular reactor, made from the catalytic material, is positioned in a vacuum chamber. Expansion of the gas through a 100 μm sampling orifice in the reactor wall into differentially pumped nozzle, skimmer, and collimator chambers leads to the formation of a molecular beam. A quadrupole mass spectrometer with electron impact ion source designed for molecular beam inlet and threshold ionization measurements is used as the analyzer. The sampling time from nozzle to detector is estimated to be less than 10 ms. A detection time resolution of up to 20 ms can be reached. The temperature of the reactor is measured by pyrometry. Besides a detailed description of the setup components and the physical background of the method, this article presents measurements showing the performance of the apparatus. After deriving the shape and width of the energy spread of the ionizing electrons from measurements on N 2 and He we estimated the detection limit in threshold ionization measurements using binary mixtures of CO in N 2 to be in the range of several hundreds of ppm. Mass spectra and threshold ionization measurements recorded during catalytic partial oxidation of methane at 1250 deg. C on a Pt catalyst are presented. The detection of CH 3 · radicals is successfully demonstrated

Molecular beam mass spectrometer equipped with a catalytic wall reactor for in situ studies in high temperature catalysis research

Science.gov (United States)

Horn, R.; Ihmann, K.; Ihmann, J.; Jentoft, F. C.; Geske, M.; Taha, A.; Pelzer, K.; Schlögl, R.

2006-05-01

A newly developed apparatus combining a molecular beam mass spectrometer and a catalytic wall reactor is described. The setup has been developed for in situ studies of high temperature catalytic reactions (>1000°C), which involve besides surface reactions also gas phase reactions in their mechanism. The goal is to identify gas phase radicals by threshold ionization. A tubular reactor, made from the catalytic material, is positioned in a vacuum chamber. Expansion of the gas through a 100μm sampling orifice in the reactor wall into differentially pumped nozzle, skimmer, and collimator chambers leads to the formation of a molecular beam. A quadrupole mass spectrometer with electron impact ion source designed for molecular beam inlet and threshold ionization measurements is used as the analyzer. The sampling time from nozzle to detector is estimated to be less than 10ms. A detection time resolution of up to 20ms can be reached. The temperature of the reactor is measured by pyrometry. Besides a detailed description of the setup components and the physical background of the method, this article presents measurements showing the performance of the apparatus. After deriving the shape and width of the energy spread of the ionizing electrons from measurements on N2 and He we estimated the detection limit in threshold ionization measurements using binary mixtures of CO in N2 to be in the range of several hundreds of ppm. Mass spectra and threshold ionization measurements recorded during catalytic partial oxidation of methane at 1250°C on a Pt catalyst are presented. The detection of CH3• radicals is successfully demonstrated.

Atmospheric pressure flow reactor: Gas phase chemical kinetics under tropospheric conditions without wall effects

Science.gov (United States)

Koontz, Steven L. (Inventor); Davis, Dennis D. (Inventor)

1991-01-01

A flow reactor for simulating the interaction in the troposphere is set forth. A first reactant mixed with a carrier gas is delivered from a pump and flows through a duct having louvers therein. The louvers straighten out the flow, reduce turbulence and provide laminar flow discharge from the duct. A second reactant delivered from a source through a pump is input into the flowing stream, the second reactant being diffused through a plurality of small diffusion tubes to avoid disturbing the laminar flow. The commingled first and second reactants in the carrier gas are then directed along an elongated duct where the walls are spaced away from the flow of reactants to avoid wall interference, disturbance or turbulence arising from the walls. A probe connected with a measuring device can be inserted through various sampling ports in the second duct to complete measurements of the first and second reactants and the product of their reaction at selected XYZ locations relative to the flowing system.

Optimization Study of Hydrogen Gas Adsorption on Zig-zag Single-walled Carbon Nanotubes: The Artificial Neural Network Analysis

Science.gov (United States)

Nasruddin; Lestari, M.; Supriyadi; Sholahudin

2018-03-01

The use of hydrogen gas in fuel cell technology has a huge opportunity to be applied in upcoming vehicle technology. One of the most important problems in fuel cell technology is the hydrogen storage. The adsorption of hydrogen in carbon-based materials attracts a lot of attention because of its reliability. This study investigated the adsorption of hydrogen gas in Single-walled Carbon Nano Tubes (SWCNT) with chilarity of (0, 12), (0, 15), and (0, 18) to find the optimum chilarity. Artificial Neural Networks (ANN) can be used to predict the hydrogen storage capacity at different pressure and temperature conditions appropriately, using simulated series of data. The Artificial Neural Network is modeled as a predictor of the hydrogen adsorption capacity which provides solutions to some deficiencies in molecular dynamics (MD) simulations. In a previous study, ANN configurations have been developed for 77k, 233k, and 298k temperatures in hydrogen gas storage. To prepare this prediction, ANN is modeled to find out the configurations that exist in the set of training and validation of specified data selection, the distance between data, and the number of neurons that produce the smallest error. This configuration is needed to make an accurate artificial neural network. The configuration of neural network was then applied to this research. The neural network analysis results show that the best configuration of artificial neural network in hydrogen storage is at 233K temperature i.e. on SWCNT with chilarity of (0.12).

A thermodynamic approach on vapor-condensation of corrosive salts from flue gas on boiler tubes in waste incinerators

International Nuclear Information System (INIS)

Otsuka, Nobuo

2008-01-01

Thermodynamic equilibrium calculation was conducted to understand the effects of tube wall temperature, flue gas temperature, and waste chemistry on the type and amount of vapor-condensed 'corrosive' salts from flue gas on superheater and waterwall tubes in waste incinerators. The amount of vapor-condensed compounds from flue gases at 650-950 deg. C on tube walls at 350-850 deg. C was calculated, upon combustion of 100 g waste with 1.6 stoichiometry (in terms of the air-fuel ratio). Flue gas temperature, rather than tube wall temperature, influenced the deposit chemistry of boiler tubes significantly. Chlorine, sulfur, sodium, potassium, and calcium contents in waste affected it as well

The influence of insulation of walls of industrial objects on thermal regime at the heating system of gas infrared radiators

Directory of Open Access Journals (Sweden)

Nagornova Tatiana

2017-01-01

Full Text Available The results of a numerical study of the process of heat transfer from the gas infrared emitters in the heated accommodation are represented. Simulation was conducted taking into account the heat withdrawal in the enclosing constructions and of heat exchange with the environment. The estimation of the average values of temperatures of air indoors in the dependence on the different intensity of heat withdrawal into the vertical walls is carried out (when the layer of insulation is present, and without it.

Numerical analysis of a PCM thermal storage system with varying wall temperature

International Nuclear Information System (INIS)

Halawa, E.; Bruno, F.; Saman, W.

2005-01-01

Numerical analysis of melting and freezing of a PCM thermal storage unit (TSU) with varying wall temperature is presented. The TSU under analysis consists of several layers of thin slabs of a PCM subjected to convective boundary conditions where air flows between the slabs. The model employed takes into account the variations in wall temperature along the direction of air flow as well as the sensible heat. The paper discusses typical characteristics of the melting/freezing of PCM slabs in an air stream and presents some results of the numerical simulation in terms of air outlet temperatures and heat transfer rates during the whole periods of melting and freezing. Considerations in the design of the TSU are also given

Exposure of a liquefied gas container to an external fire

International Nuclear Information System (INIS)

Raj, Phani K.

2005-01-01

In liquefied gas, bulk-storage facilities and plants, the separation distances between storage tanks and between a tank and a line of adjoining property that can be built are governed by local regulations and/or codes (e.g. National Fire Protection Association (NFPA) 58, 2004). Separation distance requirements have been in the NFPA 58 Code for over 60 years; however, no scientific foundations (either theoretical or experimental) are available for the specified distances. Even though the liquefied petroleum gas (LPG) industry has operated safely over the years, there is a question as to whether the code-specified distances provide sufficient safety to LPG-storage tanks, when they are exposed to large external fires. A radiation heat-transfer-based model is presented in this paper. The temporal variation of the vapor-wetted tank-wall temperature is calculated when exposed to thermal radiation from an external, non-impinging, large, 30.5 m (100 ft) diameter, highly radiative, hydrocarbon fuel (pool) fire located at a specified distance. Structural steel wall of a pressurized, liquefied gas container (such as the ASME LP-Gas tank) begins to lose its strength, when the wall temperature approaches a critical temperature, 810 K (1000 deg F). LP-Gas tank walls reaching close to this temperature will be a cause for major concern because of increased potential for tank failure, which could result in catastrophic consequences. Results from the model for exposure of different size ASME (LP-Gas) containers to a hydrocarbon pool fire of 30.5 m (100 ft) in diameter, located with its base edge at the separation distances specified by NFPA 58 [NFPA 58, Liquefied Petroleum Gas Code, Table 6.3.1, 2004 ed., National Fire Protection Association, Quincy, MA, 2004] indicate that the vapor-wetted wall temperature of the containers never reach the critical temperature under common wind conditions (0, 5 and 10 m/s), with the flame tilting towards the tank. This indicates that the separation

Temperature modulates the cell wall mechanical properties of rice coleoptiles by altering the molecular mass of hemicellulosic polysaccharides

Science.gov (United States)

Nakamura, Yukiko; Wakabayashi, Kazuyuki; Hoson, Takayuki

2003-01-01

The present study was conducted to investigate the mechanism inducing the difference in the cell wall extensibility of rice (Oryza sativa L. cv. Koshihikari) coleoptiles grown under various temperature (10-50 degrees C) conditions. The growth rate and the cell wall extensibility of rice coleoptiles exhibited the maximum value at 30-40 degrees C, and became smaller as the growth temperature rose or dropped from this temperature range. The amounts of cell wall polysaccharides per unit length of coleoptile increased in coleoptiles grown at 40 degrees C, but not at other temperature conditions. On the other hand, the molecular size of hemicellulosic polysaccharides was small at temperatures where the cell wall extensibility was high (30-40 degrees C). The autolytic activities of cell walls obtained from coleoptiles grown at 30 and 40 degrees C were substantially higher than those grown at 10, 20 and 50 degrees C. Furthermore, the activities of (1-->3),(1-->4)-beta-glucanases extracted from coleoptile cell walls showed a similar tendency. When oat (1-->3),(1-->4)-beta-glucans with high molecular mass were incubated with the cell wall enzyme preparations from coleoptiles grown at various temperature conditions, the extensive molecular mass downshifts were brought about only by the cell wall enzymes obtained from coleoptiles grown at 30-40 degrees C. There were close correlations between the cell wall extensibility and the molecular mass of hemicellulosic polysaccharides or the activity of beta -glucanases. These results suggest that the environmental temperature regulates the cell wall extensibility of rice coleoptiles by modifying mainly the molecular mass of hemicellulosic polysaccharides. Modulation of the activity of beta-glucanases under various temperature conditions may be involved in the alteration of the molecular size of hemicellulosic polysaccharides.

A concise wall temperature model for DI Diesel engines

Energy Technology Data Exchange (ETDEWEB)

Torregrosa, A.; Olmeda, P.; Degraeuwe, B. [CMT-Motores Termicos, Universidad Politecnica de Valencia (Spain); Reyes, M. [Centro de Mecanica de Fluidos y Aplicaciones, Universidad Simon Bolivar (Venezuela)

2006-08-15

A concise resistor model for wall temperature prediction in diesel engines with piston cooling is presented here. The model uses the instantaneous in-cylinder pressure and some usually measured operational parameters to predict the temperature of the structural elements of the engine. The resistor model was adjusted by means of temperature measurements in the cylinder head, the liner and the piston. For each model parameter, an expression as a function of the engine geometry, operational parameters and material properties was derived to make the model applicable to other similar engines. The model predicts well the cylinder head, liner and piston temperature and is sensitive to variations of operational parameters such as the start of injection, coolant and oil temperature and engine speed and load. (author)

Wall-shaped hohlraum influence on symmetry and energetics in gas-filled hohlraums

Science.gov (United States)

Tassin, Veronique; Philippe, Franck; Laffite, Stephane; Videau, Laurent; Monteil, Marie-Christine; Villette, Bruno; Stemmler, Philippe; Bednarczyk, Sophie; Peche, Emilie; Reneaume, Benoit; Thessieux, Christian

2008-11-01

On the way to the LMJ completion, achieving ignition with 40 quads in a 2-cone configuration will be attempted as a first step. Theoretical investigation of a rugby-shaped hohlraum shows energetics optimization and a better symmetry control compared to a cylindrical hohlraum [1]. We recently conducted experiments on the Omega laser facility with 3 different wall-shaped methane-filled hohlraum configurations. We present here the experimental results. Energetics benefits are shown for reduced wall area hohlraums. The wall-shaped hohlraum influence on time-dependent radiation symmetry is also discussed. For the 3 gas-filled hohlraums configurations, we compare the foamball early-time radiographs, the D2Ar-filled capsule time-integrated images and the core self-emission images. [1] M. Vandenboomgaerde, Phys. Rev. Lett., 99, 065004 (2007).

Wall temperature measurements using a thermal imaging camera with temperature-dependent emissivity corrections

International Nuclear Information System (INIS)

McDaid, Chloe; Zhang, Yang

2011-01-01

A methodology is presented whereby the relationship between temperature and emissivity for fused quartz has been used to correct the temperature values of a quartz impingement plate detected by an SC3000 thermal imaging camera. The methodology uses an iterative method using the initial temperature (obtained by assuming a constant emissivity) to find the emissivity values which are then put into the thermal imaging software and used to find the subsequent temperatures, which are used to find the emissivities, and so on until converged. This method is used for a quartz impingement plate that has been heated under various flame conditions, and the results are compared. Radiation losses from the plate are also calculated, and it is shown that even a slight change in temperature greatly affects the radiation loss. It is a general methodology that can be used for any wall material whose emissivity is a function of temperature

INTERACTION OF LIQUID FLAT SCREENS WITH GAS FLOW RESTRICTED BY CHANNEL WALLS

Directory of Open Access Journals (Sweden)

S. T. Aksentiev

2005-01-01

Full Text Available The paper gives description of physical pattern of liquid screen interaction that are injected from the internal walls of a rectangular channel with gas flow. Criterion dependences for determination of intersection coordinates of external boundaries with longitudinal channel axis and factor of liquid screen head resistance.

Temperature and displacement transients in inertial confinement fusion first-walls

International Nuclear Information System (INIS)

Hunter, T.O.; Kulcinski, G.L.

1977-01-01

A quasi-analytic general model is developed for determination of temperature response and displacement damage in materials exposed to bursts of thermonuclear radiations. Temperature response can be determined for any time or position. Materials are assessed, using the model, which might be employed for dry first walls, collectors, laser mirrors, or other exposed reactor components. The resulting magnitude and temporal distribution of temperature and displacement production show that effects on material micro-structure must be treated in a dynamic fashion

Temperature dependence of the domain wall magneto-Seebeck effect: avoiding artifacts of lead contributions

Science.gov (United States)

Fernández Scarioni, Alexander; Krzysteczko, Patryk; Sievers, Sibylle; Hu, Xiukun; Schumacher, Hans W.

2018-06-01

We study the resistive and thermopower signatures of a single domain wall in a magnetic nanowire in the temperature range from 4 K to 204 K. The results are compared to the anisotropic magnetoresistance (AMR) and anisotropic magneto-Seebeck (AMS) data of the whole permalloy nanowire. The AMS ratio of the nanowire reveals a sign change at a temperature of 98 K, while the AMR ratio is positive over the complete temperature range. This behavior is also observed for the domain wall, allowing an attribution of the measured signatures to the domain wall magneto-Seebeck and domain wall magnetoresistive contributions. However, the observed zero crossing of the AMS ratio, in both types of measurements is not expected for permalloy, since the Mott formula predicts a temperature dependency of the AMS identical to the AMR. We discuss the origin of this behavior and can attribute it to the contributions of the lead and the protective platinum layer used in our devices. A correction scheme is presented and applied. Such contributions could also play a role in the analysis of magneto-Seebeck effects in other nanoscale devices, such as the tunnel magneto-Seebeck effect of magnetic tunnel junctions.

Modifications to Langley 0.3-m TCT adaptive wall software for heavy gas test medium, phase 1 studies

Science.gov (United States)

Murthy, A. V.

1992-01-01

The scheme for two-dimensional wall adaptation with sulfur hexafluoride (SF6) as test gas in the NASA Langley Research Center 0.3-m Transonic Cryogenic Tunnel (0.3-m TCT) is presented. A unified version of the wall adaptation software has been developed to function in a dual gas operation mode (nitrogen or SF6). The feature of ideal gas calculations for nitrogen operation is retained. For SF6 operation, real gas properties have been computed using the departure function technique. Installation of the software on the 0.3-m TCT ModComp-A computer and preliminary validation with nitrogen operation were found to be satisfactory. Further validation and improvements to the software will be undertaken when the 0.3-m TCT is ready for operation with SF6 gas.

Buoyancy suppression in gases at high temperatures

International Nuclear Information System (INIS)

Kuczmarski, Maria A.; Gokoglu, Suleyman A.

2007-01-01

The computational fluid dynamics code FLUENT was used to study Rayleigh instability at large temperature differences in a sealed gas-filled enclosure with a cold top wall and a heated bottom wall (Benard problem). Both steady state and transient calculations were performed. Instability boundaries depending on the geometry, temperature, and pressure were defined that showed the system tended to become more unstable when the hot-wall temperature increased beyond a certain level, a result of the dampening effect of gas viscosity at higher temperatures. Results also showed that the eventual system stability depended on the final pressure reached at steady state, regardless of how fast the bottom-wall temperature was ramped up to minimize time spent in the unstable region of fluid motion. It was shown that the final system state can differ depending on whether results are obtained via a steady-state or transient calculation, demonstrating that the history of the flow structure development and corresponding temperature fields in this type of system has a profound effect on the final state. Finally, changes in the slope of the pressure-versus-time curve were found to be good indicators of flow pattern changes, and can be a convenient experimental tool for diagnosing the expected changes in flow behavior in such systems

Thermodynamic performance of a gas-core fission reactor

International Nuclear Information System (INIS)

Klein, W.

1987-01-01

The purpose of this thesis was to investigate the thermodynamic behaviour of a critical quantity of gaseous uranium-fluorides in chemical equilibrium with a graphite wall. From the very beginning a container was considered with cooled walls. As it was evident that a nuclear reactor working with gaseous fuel should run at much higher temperatures than classical LWR or HTGR reactors, most of the investigations were performed for walls with a surface temperature of 1800 to 2000 K. It was supposed that such a surface temperature would be technologically possible for a heat load between 1 and 5 MWatt m -2 . Cooling with high pressure helium-gas has to keep balance with this heat flux. The technical construction of such a wall will be a problem in itself. It is thought that the experiences with re-entry-vessels in space-technology can be used. A basic assumption in all the calculations is that the U-C-F reactor gas 'sees' a graphite wall, possibly graphite tiles supported by heat resistant materials like SiN 2 , SiC 2 and at a lower temperature level by niobium-steel. Such a gastight compound-system is not necessarily of high-tensile strength materials. It has to be surrounded by a cooled neutron moderator-reflector which in its turn must be supported by a steel-wall at room temperature holding pressure of the order of 100 bar (10 MPa). The design of such a compound-wall is a task for the future. 116 refs.; 28 figs.; 29 tabs

On residual gas analysis during high temperature baking of graphite tiles

International Nuclear Information System (INIS)

Prakash, A A; Chaudhuri, P; Khirwadkar, S; Reddy, D Chenna; Saxena, Y C; Chauhan, N; Raole, P M

2008-01-01

Steady-state Super-conducting Tokamak-1 (SST-1) is a medium size tokamak with major radius of 1.1 m and minor radius of 0.20 m. It is designed for plasma discharge duration of 1000 seconds to obtain fully steady-state plasma operation. Plasma Facing Components (PFC), consisting of divertors, passive stabilizers, baffles and poloidal limiters are also designed to be UHV compatible for steady state operation. All PFC are made up of graphite tiles mechanically attached to the copper alloy substrate. Graphite is one of the preferred first wall armour material in present day tokamaks. High thermal shock resistance and low atomic number of carbon are the most important properties of graphite for this application. High temperature vacuum baking of graphite tiles is the standard process to remove the impurities. Residual Gas Analyzer (RGA) has been used for qualitative and quantitative measurements of released gases from graphite tiles during baking. Surface Analysis of graphite tiles has also been done before and after baking. This paper describes the residual gas analysis during baking and surface analysis of graphite tiles

On residual gas analysis during high temperature baking of graphite tiles

Energy Technology Data Exchange (ETDEWEB)

Prakash, A A; Chaudhuri, P; Khirwadkar, S; Reddy, D Chenna; Saxena, Y C [Institute for Plasma Research, Bhat, Gandhinagar - 382 428 (India); Chauhan, N; Raole, P M [Facilitation Center for Industrial Plasma Technologies, IPR, Gandhinagar (India)], E-mail: arun@ipr.res.in

2008-05-01

Steady-state Super-conducting Tokamak-1 (SST-1) is a medium size tokamak with major radius of 1.1 m and minor radius of 0.20 m. It is designed for plasma discharge duration of 1000 seconds to obtain fully steady-state plasma operation. Plasma Facing Components (PFC), consisting of divertors, passive stabilizers, baffles and poloidal limiters are also designed to be UHV compatible for steady state operation. All PFC are made up of graphite tiles mechanically attached to the copper alloy substrate. Graphite is one of the preferred first wall armour material in present day tokamaks. High thermal shock resistance and low atomic number of carbon are the most important properties of graphite for this application. High temperature vacuum baking of graphite tiles is the standard process to remove the impurities. Residual Gas Analyzer (RGA) has been used for qualitative and quantitative measurements of released gases from graphite tiles during baking. Surface Analysis of graphite tiles has also been done before and after baking. This paper describes the residual gas analysis during baking and surface analysis of graphite tiles.

Performance evaluation of Maxwell and Cercignani-Lampis gas-wall interaction models in the modeling of thermally driven rarefied gas transport

KAUST Repository

Liang, Tengfei; Li, Qi; Ye, Wenjing

2013-01-01

A systematic study on the performance of two empirical gas-wall interaction models, the Maxwell model and the Cercignani-Lampis (CL) model, in the entire Knudsen range is conducted. The models are evaluated by examining the accuracy of key

Local wall thickness reductions in operative high-pressure gas pipelines; Lokale Wanddickenminderungen an in Betrieb befindlichen Gashochdruckleitungen

Energy Technology Data Exchange (ETDEWEB)

Hass, Georg [Netzdienste Rhein-Main GmbH, Frankfurt am Main (Germany); Hoffmann, Ulrich [Verbundnetz Gas AG (VNG), Leipzig (Germany); Konarske, Juergen [RWE Westfalen-Weser-Ems Netzservice GmbH, Recklinghausen (Germany); Soppa, Thorsten [NG Netz Gas+Wasser (Germany); Steiner, Michael [Open Grid Europe GmbH, Essen (Germany)

2011-04-15

TUeV Nord, Salzgitter Mannesmann Forschung and DVGW investigated methods to assess local wall thickness reductions in operative high-pressure gas pipelines. Methods described in the relevant literature were reviewed with regard to the limiting criteria defined for maximum permissible wall thickness reductions. (orig./GL)

Modern gas-based temperature and pressure measurements

CERN Document Server

Pavese, Franco

2013-01-01

This 2nd edition volume of Modern Gas-Based Temperature and Pressure Measurements follows the first publication in 1992. It collects a much larger set of information, reference data, and bibliography in temperature and pressure metrology of gaseous substances, including the physical-chemical issues related to gaseous substances. The book provides solutions to practical applications where gases are used in different thermodynamic conditions. Modern Gas-Based Temperature and Pressure Measurements, 2nd edition is the only comprehensive survey of methods for pressure measurement in gaseous media used in the medium-to-low pressure range closely connected with thermometry. It assembles current information on thermometry and manometry that involve the use of gaseous substances which are likely to be valid methods for the future. As such, it is an important resource for the researcher. This edition is updated through the very latest scientific and technical developments of gas-based temperature and pressure measurem...

Forced convection heat transfer in rectangular ducts: general case of wall resistances and peripheral conduction

Energy Technology Data Exchange (ETDEWEB)

Lyczkowski, R. W. [Institute of Gas Technology, Chicago, IL (United States); Solbrig, C. W. [Commonwealth Edison Co., Chicago, IL (United States); Gidaspow, D. [Illinois Inst. of Technology, Chicago, IL (United States)

1980-01-01

A numerical solution for laminar flow heat transfer between a flowing gas and its containing rectangular duct has been obtained for many different boundary conditions. The problem has been solved for the cases of insulation on no walls, one wall, two walls, and three walls with various finite resistances on the remaining walls. Results have been obtained for several duct aspect ratios in the thermal entrance and in the fully developed regions, including the constant temperature cases. When one wall is insulated and the other three are at constant temperature, the maximum temperature occurs in the fluid rather than on the insulated wall. This maximum moves toward the insulated wall with increasing axial distance. Nusselt numbers for the same constant flux on all four walls with peripheral conduction lie in a narrow band bounded by zero and infinite peripheral conduction cases. A dimensionless wall conduction group of four can be considered infinite for the purpose of estimating fully developed Nusselt numbers to within an accuracy of 3%. A decrease in wall and bulk temperatures by finite wall conduction has been demonstrated for the case of a black body radiation boundary condition.

An investigation of wall temperature characteristics to evaluate thermal fatigue at a T-junction pipe

International Nuclear Information System (INIS)

Miyoshi, Koji; Nakamura, Akira; Utanohara, Yoichi; Takenaka, Nobuyuki

2014-01-01

Thermal fatigue cracking may initiate at a T-junction pipe where high and low temperature fluids mix. In this study, wall temperature characteristics at a T-junction pipe were investigated to improve the evaluation method for thermal fatigue. The stainless steel test section consisted of a horizontal main pipe (diameter, 150 mm) and a T-junction connected to a vertical branch pipe (diameter, 50 mm). The inlet flow velocities in the main and branch pipes were set to 0.99 m/s and 0.66 m/s respectively to produce a wall jet pattern in which the jet from the branch pipe was bent by the main pipe flow and made to flow along the pipe wall. The temperature difference was 34.1 K. A total of 148 thermocouples were installed to measure the wall temperature on the pipe inner surface in the downstream region. The maximum of temperature fluctuation intensity on the pipe inner surface was measured as 5% of the fluid temperature difference at the inlets. The dominant frequency of the large temperature fluctuations in the region downstream from z = 0.5D m was equal to 0.2 of the Strouhal number, which was equal to the frequency caused by the vortex streets generated around the jet flow. The large temperature fluctuation was also observed with the period of about 10 s. The fluctuation was caused by spreading of the heated region in the circumferential direction. (author)

High temperature gas-cooled reactor: gas turbine application study

Energy Technology Data Exchange (ETDEWEB)

1980-12-01

The high-temperature capability of the High-Temperature Gas-Cooled Reactor (HTGR) is a distinguishing characteristic which has long been recognized as significant both within the US and within foreign nuclear energy programs. This high-temperature capability of the HTGR concept leads to increased efficiency in conventional applications and, in addition, makes possible a number of unique applications in both electrical generation and industrial process heat. In particular, coupling the HTGR nuclear heat source to the Brayton (gas turbine) Cycle offers significant potential benefits to operating utilities. This HTGR-GT Application Study documents the effort to evaluate the appropriateness of the HTGR-GT as an HTGR Lead Project. The scope of this effort included evaluation of the HTGR-GT technology, evaluation of potential HTGR-GT markets, assessment of the economics of commercial HTGR-GT plants, and evaluation of the program and expenditures necessary to establish HTGR-GT technology through the completion of the Lead Project.

High temperature gas-cooled reactor: gas turbine application study

International Nuclear Information System (INIS)

1980-12-01

The high-temperature capability of the High-Temperature Gas-Cooled Reactor (HTGR) is a distinguishing characteristic which has long been recognized as significant both within the US and within foreign nuclear energy programs. This high-temperature capability of the HTGR concept leads to increased efficiency in conventional applications and, in addition, makes possible a number of unique applications in both electrical generation and industrial process heat. In particular, coupling the HTGR nuclear heat source to the Brayton (gas turbine) Cycle offers significant potential benefits to operating utilities. This HTGR-GT Application Study documents the effort to evaluate the appropriateness of the HTGR-GT as an HTGR Lead Project. The scope of this effort included evaluation of the HTGR-GT technology, evaluation of potential HTGR-GT markets, assessment of the economics of commercial HTGR-GT plants, and evaluation of the program and expenditures necessary to establish HTGR-GT technology through the completion of the Lead Project

Novel silica membranes for high temperature gas separations

KAUST Repository

Bighane, Neha; Koros, William J.

2011-01-01

and pure gas separation performance in the temperature range 35-80°C is presented. It is observed that the membranes exhibit activated transport for small gas penetrants such as He, H 2 and CO 2. The membranes can withstand temperatures up to 350°C in air

Continuously renewed wall for a thermonuclear reactor

International Nuclear Information System (INIS)

Livshits, A.I.; Pustovojt, YU.M.; Samartsev, A.A.; Gosudarstvennyj Komitet po Ispol'zovaniyu Atomnoj Ehnergii SSSR, Moscow. Inst. Atomnoj Ehnergii)

1982-01-01

The possibility of creating a continuously renewed first wall of a thermonuclear reactor is experimentally investigated. The following variants of the wall are considered: the wall is double, its part turned to plasma is made of comparatively thin material. The external part separated from it by a small gap appears to be protected from interaction with plasma and performs structural functions. The gap contains the mixture of light helium and hydrogen and carbon-containing gas. The light gas transfers heat from internal part of the wall to the external part. Carbon-containing gas provides continuous renewal of carbon coating of the operating surface. The experiment is performed with palladium membrane 20 μm thick. Carbon is introduced into the membrane by benzol pyrolysis on one of the surfaces at the membrane temperature of 900 K. Carbon removal from the operating side of the wall due to its spraying by fast particles is modelled by chemical itching with oxygen given to the operating membrane wall. Observation of the carbon release on the operating surface is performed mass-spectrometrically according to the observation over O 2 transformation into CO and CO 2 . It is shown that in cases of benzol pressure of 5x10 -7 torr, carbon current on the opposite surface is not less than 3x10 12 atoms/sm 2 s and corresponds to the expected wall spraying rate in CF thermonuclear reactors. It is also shown that under definite conditions the formation and maintaining of a through protective carbon coating in the form of a monolayer or volumetric phase is possible

Device to remove hydrogen isotopes from a gas phase

International Nuclear Information System (INIS)

Morlock, G.; Wiesemes, J.; Bachner, D.

1977-01-01

The device described here guarantees the selective removal of hydrogen isotopes from gas phases in order to prevent the occurence of explosive H 2 gas mixtures, or to separate off radioactive tritium in nuclear plants from the gas phase. It consists of a closed container whose walls are selectively penetrable by hydrogen isotopes. It is simultaneously filled compactly and presssure-resistant with a metal bulk (e.g. powder, sponges or the like of titanium or other hydrogen isotope binding metal). Walling and bulk are maintained at suitable working temperatures by means of a system according to the Peltier effect. The whole thing is safeguarded by protective walling. (RB) [de

Apparatus using radioactive particles for measuring gas temperatures

International Nuclear Information System (INIS)

Compton, W.A.; Duffy, T.E.; Seegall, M.I.

1975-01-01

Apparatus for producing a signal indicative of the temperature of a heated gas is described comprising a beta particle source; a beta particle detector which intercepts particles emitted from said source; circuitry for converting the detector output to a signal indicative of the density of the gas; a pressure transducer for generating a signal indicative of the pressure on the gas; and circuitry for dividing the pressure signal by the density signal to produce a signal indicative of the average temperature of the gas along the path between the beta particle source and the beta particle detector. (auth)

Examining Methods to Reduce Wall-Wetting under HCCI conditions

Energy Technology Data Exchange (ETDEWEB)

Van Erp, D.D.T.M.

2009-01-15

HCCI engines (Homogeneous Charge Compression Ignition) are very promising in the reduction of soot and NOx, but several problems must be tackled. Collision of the liquid fuel spray against the cylinder wall (Wall-wetting) is a major problem. Low gas temperatures and low gas densities (typical 600 - 800 K and 5 - 7.4 kg/m{sup 3}) at the moment of the fuel injection slow down the evaporation process of the liquid fuel in the spray and causes wall-wetting. This report investigates different promising measures that can reduce the penetration of the liquid fuel core, in order to prevent wall-wetting. From literature it turns out that the measures, listed below, are the most promising for liquid core length (LL) reduction without changing the design of the injector or the engine design: Increasing the fuel temperature, Changing the fuel pressure, Decrease of injector hole diameter, Multiple injections (first very short injections are examined). Each of the measures will be investigated by a liquid length prediction model (Siebers) and in an experimental setup, the EHPC (Eindhoven High Pressure Cell). A high pressure vessel with optical access makes it possible to visualize the liquid core and the vapor phase of the fuel spray by Mie and Schlieren, respectively. Changes to the setup are made to heat up the fuel up to 120C. Furthermore, changes to the fuel spray visualization techniques have been made. Where in previous experiments the Mie and Schlieren techniques were carried out separately from each other, in this work both visualization techniques are combined to save measurement time and to deal with the same experimental conditions. The combined recording of Mie and Schlieren works well for high gas temperatures and densities. But the combined technique fails for low gas temperatures and densities (below 700K and 7.4 kg/m3), due to the poor contrast between the liquid core and the vapor phase. In further examination of liquid length reducing measures, only the Mie

Thermal boundary conditions for electrons in a weakly ionized gas near a catalytic wall

International Nuclear Information System (INIS)

Chekmarev, I.

1981-01-01

A technique of matched asymptotic expansions is used to examine the derivation of hydrodynamic transport equations for the external region of a weakly ionized multitemperature gas near an absorbing and conducting wall. An approximate moment solution is constructed for the Knudsen boundary layer. The conditions for the matching of the external and internal expansions lead to a new form of the hydrodynamic boundary conditions, from which the singular behavior of the energy equation for electrons near the wall has been eliminated

Measured gas and particle temperatures in VTT's entrained flow reactor

DEFF Research Database (Denmark)

Clausen, Sønnik; Sørensen, L.H.

2006-01-01

Particle and gas temperature measurements were carried out in experiments on VTTs entrained flow reactor with 5% and 10% oxygen using Fourier transform infrared emission spectroscopy (FTIR). Particle temperature measurements were performed on polish coal,bark, wood, straw particles, and bark...... and wood particles treated with additive. A two-color technique with subtraction of the background light was used to estimate particle temperatures during experiments. A transmission-emission technique was used tomeasure the gas temperature in the reactor tube. Gas temperature measurements were in good...... agreement with thermocouple readings. Gas lines and bands from CO, CO2 and H2O can be observed in the spectra. CO was only observed at the first measuring port (100ms) with the strongest CO-signal seen during experiments with straw particles. Variations in gas concentration (CO2 and H2O) and the signal from...

Steam conversion of liquefied petroleum gas and methane in microchannel reactor

Science.gov (United States)

Dimov, S. V.; Gasenko, O. A.; Fokin, M. I.; Kuznetsov, V. V.

2018-03-01

This study presents experimental results of steam conversion of liquefied petroleum gas and methane in annular catalytic reactor - heat exchanger. The steam reforming was done on the Rh/Al2O3 nanocatalyst with the heat applied through the microchannel gap from the outer wall. Concentrations of the products of chemical reactions in the outlet gas mixture are measured at different temperatures of reactor. The range of channel wall temperatures at which the ratio of hydrogen and carbon oxide in the outlet mixture grows substantially is determined. Data on the composition of liquefied petroleum gas conversion products for the ratio S/C = 5 was received for different GHVS.

Optimization of Steady Wall Temperature for Disturbance Control

OpenAIRE

Pralits, Jan; Ardeshir, Hanifi

2003-01-01

We present a theory for computing the optimal steady wall temperature distribution to suppress the growth of convectively unstable disturbances in compressible boundary layer flows on flat plates. A gradient based iterative procedure is used to minimize an objective function measuring the disturbance kinetic energy. The gradient of interest is obtained from the solution of the adjoint of the boundary layer and parabolized stability equations, which are derived using a Lagrange multiplier tech...

Integrated Life Cycle Energy and Greenhouse Gas Analysis of Exterior Wall Systems for Residential Buildings

Directory of Open Access Journals (Sweden)

Reza Broun

2014-11-01

Full Text Available This paper investigates the breakdown of primary energy use and greenhouse gas (GHG emissions of two common types of exterior walls in the U.K.: insulated concrete form (ICF and cavity walls. A comprehensive assessment was conducted to evaluate the environmental performance of each exterior wall system over 50 years of service life in Edinburgh and Bristol. The results indicate that for both wall systems, use phase is the major contributor to the overall environmental impacts, mainly due to associated electricity consumption. For the ICF wall system in Edinburgh, 91% of GHG emissions were attributed to the use phase, with 7.8% in the pre-use and 1.2% in end-of-life phases. For the same system in Bristol, emissions were 89%, 9% and 2%, respectively. A similar trend was observed for cavity wall systems in both locations. It was concluded that in each scenario, the ICF wall system performed better when compared to the cavity wall system. The results of the sensitivity analysis clearly show that the uncertainties relevant to the change of the thickness of the wall are quite tolerable: variable up to 5%, as far as energy and greenhouse emissions are concerned.

Numerical calculation of wall-to-bed heat transfer coefficients in gas-fluidized beds

NARCIS (Netherlands)

Kuipers, J.A.M.; Prins, W.; van Swaaij, W.P.M.

1992-01-01

A computer model for a hot gas-fluidized bed has been developed. The theoretical description is based on a two-fluid model (TFM) approach in which both phases are considered to be continuous and fully interpenetrating. Local wall-to-bed heat-transfer coefficients have been calculated by the

Conceptual Engineering Method for Attenuating He Ion Interactions on First Wall Components in the Fusion Test Facility (FTF) Employing a Low-Pressure Noble Gas

International Nuclear Information System (INIS)

Gentile, C.A.; Blanchard, W.R.; Kozub, T.; Priniski, C.; Zatz, I.; Obenschain, S.

2009-01-01

It has been shown that post detonation energetic helium ions can drastically reduce the useful life of the (dry) first wall of an IFE reactor due to the accumulation of implanted helium. For the purpose of attenuating energetic helium ions from interacting with first wall components in the Fusion Test Facility (FTF) target chamber, several concepts have been advanced. These include magnetic intervention (MI), deployment of a dynamically moving first wall, use of a sacrificial shroud, designing the target chamber large enough to mitigate the damage caused by He ions on the target chamber wall, and the use of a low pressure noble gas resident in the target chamber during pulse power operations. It is proposed that employing a low-pressure (∼ 1 torr equivalent) noble gas in the target chamber will thermalize energetic helium ions prior to interaction with the wall. The principle benefit of this concept is the simplicity of the design and the utilization of (modified) existing technologies for pumping and processing the noble ambient gas. Although the gas load in the system would be increased over other proposed methods, the use of a 'gas shield' may provide a cost effective method of greatly extending the first wall of the target chamber. An engineering study has been initiated to investigate conceptual engineering methods for implementing a viable gas shield strategy in the FTF.

Novel silica membranes for high temperature gas separations

KAUST Repository

Bighane, Neha

2011-04-01

This article describes fabrication of novel silica membranes derived via controlled oxidative thermolysis of polydimethylsiloxane and their gas separation performance. The optimized protocol for fabrication of the silica membranes is described and pure gas separation performance in the temperature range 35-80°C is presented. It is observed that the membranes exhibit activated transport for small gas penetrants such as He, H 2 and CO 2. The membranes can withstand temperatures up to 350°C in air and may ultimately find use in H 2/CO 2 separations to improve efficiency in the water-gas shift reactor process. © 2011 Elsevier B.V.

A porous medium model for predicting the duct wall temperature of sodium fast reactor fuel assembly

Energy Technology Data Exchange (ETDEWEB)

Yu, Yiqi, E-mail: yyu@anl.gov [Nuclear Engineering Division, Argonne National Laboratory, Lemont, IL 60439 (United States); Merzari, Elia; Obabko, Aleksandr [Mathematics and Computer Science Division, Argonne National Laboratory, Lemont, IL 60439 (United States); Thomas, Justin [Nuclear Engineering Division, Argonne National Laboratory, Lemont, IL 60439 (United States)

2015-12-15

Highlights: • The proposed models are 400 times less computationally expensive than CFD simulations. • The proposed models show good duct wall temperature agreement with CFD simulations. • The paper provides an efficient tool for coupled radial core expansion calculation. - Abstract: Porous medium models have been established for predicting duct wall temperature of sodium fast reactor rod bundle assembly, which is much less computationally expensive than conventional CFD simulations that explicitly represent the wire-wrap and fuel pin geometry. Three porous medium models are proposed in this paper. Porous medium model 1 takes the whole assembly as one porous medium of uniform characteristics in the conventional approach. Porous medium model 2 distinguishes the pins along the assembly's edge from those in the interior with two distinct regions, each with a distinct porosity, resistance, and volumetric heat source. This accounts for the different fuel-to-coolant volume ratio in the two regions, which is important for predicting the temperature of the assembly's exterior duct wall. In Porous medium model 3, a precise resistance distribution was employed to define the characteristic of the porous medium. The results show that both porous medium model 2 and 3 can capture the average duct wall temperature well. Furthermore, the local duct wall variations due to different sub-channel patterns in bare rod bundles are well captured by porous medium model 3, although the wire effect on the duct wall temperature in wire wrap rod bundle has not been fully reproduced yet.

Seismic test of high temperature piping for HTGR

International Nuclear Information System (INIS)

Kobatake, Kiyokazu; Midoriyama, Shigeru; Ooka, Yuzi; Suzuki, Michiaki; Katsuki, Taketsugu

1983-01-01

Since the high temperature pipings for the high temperature gas-cooled reactor contain helium gas at 1000 deg C and 40 kgf/cm 2 , the double-walled pipe type consisting of the external pipe serving as the pressure boundary and the internal pipe with heat insulating structure was adopted. Accordingly, their aseismatic design is one of the important subjects. Recently, for the purpose of grasping the vibration characteristics of these high temperature pipings and obtaining the data required for the aseismatic design, two specimens, that is, a double-walled pipe model and a heat-insulating structure, were made, and the vibration test was carried out on them, using a 30 ton vibration table of Kawasaki Heavy Industries Ltd. In the high temperature pipings of the primary cooling system for the multi-purpose, high temperature gas-cooled experimental reactor, the external pipes of 32 B bore as the pressure boundary and the internal pipes of 26 B bore with internal heat insulation consisting of double layers of fiber and laminated metal insulators as the temperature boundary were adopted. The testing method and the results are reported. As the spring constant of spacers is larger and clearance is smaller, the earthquake wave response of double-walled pipes is smaller, and it is more advantageous. The aseismatic property of the heat insulation structure is sufficient. (Kako, I.)

Multiple-walled BN nanotubes obtained with a mechanical alloying technique

International Nuclear Information System (INIS)

Rosas, G.; Sistos, J.; Ascencio, J.A.; Medina, A.; Perez, R.

2005-01-01

An experimental method to obtain multiple-walled nanotubes of BN using low energy is presented. The method is based on the use of mechanical alloying techniques with elemental boron powders and nitrogen gas mixed in an autoclave at room temperature. The chemical and structural characteristics of the multiple-walled nanotubes were obtained using different techniques, such as X-ray diffraction, transmission electron microscopy, EELS microanalysis, high-resolution electron microscopy images and theoretical simulations based on the multisliced approach of the electron diffraction theory. This investigation clearly illustrates the production of multiple-wall BN nanotubes at room temperature. These results open up a new kind of synthesis method with low expense and important perspectives for use in large-quantity production. (orig.)

Silicon Carbide-Based Hydrogen Gas Sensors for High-Temperature Applications

Directory of Open Access Journals (Sweden)

Sangchoel Kim

2013-10-01

Full Text Available We investigated SiC-based hydrogen gas sensors with metal-insulator-semiconductor (MIS structure for high temperature process monitoring and leak detection applications in fields such as the automotive, chemical and petroleum industries. In this work, a thin tantalum oxide (Ta2O5 layer was exploited with the purpose of sensitivity improvement, because tantalum oxide has good stability at high temperature with high permeability for hydrogen gas. Silicon carbide (SiC was used as a substrate for high-temperature applications. We fabricated Pd/Ta2O5/SiC-based hydrogen gas sensors, and the dependence of their I-V characteristics and capacitance response properties on hydrogen concentrations were analyzed in the temperature range from room temperature to 500 °C. According to the results, our sensor shows promising performance for hydrogen gas detection at high temperatures.

Dynamics of premixed flames in a narrow channel with a step-wise wall temperature

Energy Technology Data Exchange (ETDEWEB)

Kurdyumov, Vadim N. [Department of Energy, CIEMAT, Avda. Complutense 22, 28040 Madrid (Spain); Pizza, Gianmarco [Aerothermochemistry and Combustion Systems Laboratory, Swiss Federal Institute of Technology, Zurich CH-8092 (Switzerland); Combustion Research, Paul Scherrer Institute, Villigen CH-5232 (Switzerland); Frouzakis, Christos E. [Aerothermochemistry and Combustion Systems Laboratory, Swiss Federal Institute of Technology, Zurich CH-8092 (Switzerland); Mantzaras, John [Combustion Research, Paul Scherrer Institute, Villigen CH-5232 (Switzerland)

2009-11-15

The effect of channel height, inflow velocity and wall temperature on the dynamics and stability of unity Lewis number premixed flames in channels with specified wall temperature is investigated with steady and transient numerical simulations using a two-dimensional thermo-diffusive model. The simplified model is capable of capturing many of the transitions and the combustion modes observed experimentally and in direct numerical simulations in micro- and meso-scale channels, and indicates that the thermal flame/wall interaction is the mechanism leading to the observed flame instabilities. Finally, an ad-hoc one-dimensional model based on the flame-sheet approximation is tested in its capacity to reproduce some of the flame dynamics of the two-dimensional thermo-diffusive model. (author)

The Integration Of Process Heat Applications To High Temperature Gas Reactors

International Nuclear Information System (INIS)

McKellar, Michael G.

2011-01-01

A high temperature gas reactor, HTGR, can produce industrial process steam, high-temperature heat-transfer gases, and/or electricity. In conventional industrial processes, these products are generated by the combustion of fossil fuels such as coal and natural gas, resulting in significant emissions of greenhouse gases such as carbon dioxide. Heat or electricity produced in an HTGR could be used to supply process heat or electricity to conventional processes without generating any greenhouse gases. Process heat from a reactor needs to be transported by a gas to the industrial process. Two such gases were considered in this study: helium and steam. For this analysis, it was assumed that steam was delivered at 17 MPa and 540 C and helium was delivered at 7 MPa and at a variety of temperatures. The temperature of the gas returning from the industrial process and going to the HTGR must be within certain temperature ranges to maintain the correct reactor inlet temperature for a particular reactor outlet temperature. The returning gas may be below the reactor inlet temperature, ROT, but not above. The optimal return temperature produces the maximum process heat gas flow rate. For steam, the delivered pressure sets an optimal reactor outlet temperature based on the condensation temperature of the steam. ROTs greater than 769.7 C produce no additional advantage for the production of steam.

A new algorithm predicts pressure and temperature profiles of gas/gas-condensate transmission pipelines

Energy Technology Data Exchange (ETDEWEB)

Mokhatab, Saied [OIEC - Oil Industries' Engineering and Construction Group, Tehran (Iran, Islamic Republic of); Vatani, Ali [University of Tehran (Iran, Islamic Republic of)

2003-07-01

The main objective of the present study has been the development of a relatively simple analytical algorithm for predicting flow temperature and pressure profiles along the two-phase, gas/gas-condensate transmission pipelines. Results demonstrate the ability of the method to predict reasonably accurate pressure gradient and temperature gradient profiles under operating conditions. (author)

Effect of temperature on crack initiation in gas formed structures

Energy Technology Data Exchange (ETDEWEB)

Gohari, S.; Vrcelj, Z.; Sharifi, S.; Sharifishourabi, G.; Abadi, R. [Universiti Teknlogi Malaysia, Skudai (Malaysia)

2013-12-15

In the gas forming process, the work piece is formed by applying gas pressure. However, the gas pressure and the accompanying gas temperature can result in crack initiation and unstable crack growth. Thus, it is vital to determine the critical values of applied gas pressure and temperature to avoid crack and fracture failure. We studied the mechanism of fracture using an experimental approach and finite element simulations of a perfect aluminum sheet containing no inclusions and voids. The definition of crack was based on ductile damage mechanics. For inspection of initiation of crack and rupture in gas-metal forming, the ABAQUS/EXPLICIT simulation was used. In gas forming, the applied load is the pressure applied rather than the punching force. The results obtained from both the experimental approach and finite element simulations were compared. The effects of various parameters, such as temperature and gas pressure value on crack initiation, were taken into account.

Temperature and the Ideal Gas

Science.gov (United States)

Daisley, R. E.

1973-01-01

Presents some organized ideas in thermodynamics which are suitable for use with high school (GCE A level or ONC) students. Emphases are placed upon macroscopic observations and intimate connection of the modern definition of temperature with the concept of ideal gas. (CC)

Reflection of a shock wave from a thermally accommodating wall - Molecular simulation.

Science.gov (United States)

Deiwert, G. S.

1973-01-01

Reflection of a plane shock wave from a wall has been simulated on a microscopic scale using a direct simulation Monte Carlo technique of the type developed by Bird. A monatomic gas model representing argon was used to describe the fluid medium and a simple one-parameter accommodation coefficient model was used to describe the gas-surface interaction. The influence of surface accommodation was studied parametrically by varying the accommodation coefficient from zero to one. Results are presented showing the temporal variations of flow field density, and mass, momentum, and energy fluxes to the wall during the shock wave reflection process. The energy flux was used to determine the wall temperature history. Comparisons with experiment are found to be satisfactory where data are available.

Energy balance of droplets impinging onto a wall heated above the Leidenfrost temperature

International Nuclear Information System (INIS)

Dunand, P.; Castanet, G.; Gradeck, M.; Maillet, D.; Lemoine, F.

2013-01-01

Highlights: • Measurement techniques are combined to characterize the heat lost due to liquid vaporization. • The wall heat flux is estimated by infrared thermography associated with inverse heat conduction. • The liquid heating is characterized by the two-color Laser-Induced Fluorescence thermometry. • Results reveal how the heat fluxes vary with the droplet sizes and the Weber number. -- Abstract: This work is an experimental study aiming at characterizing the heat transfers induced by the impingement of water droplets (diameter 80–180 μm) on a thin nickel plate heated by electromagnetic induction. The temperature of the rear face of the nickel sample is measured by means of an infrared camera and the heat removed from the wall due to the presence of the droplets is estimated using a semi-analytical inverse heat conduction model. In parallel, the temperature of the droplets is measured using the two-color Laser-Induced Fluorescence thermometry (2cLIF) which has been extended to imagery for the purpose of these experiments. The measurements of the variation in the droplet temperature occurring during an impact allow determining the sensible heat removed by the liquid. Measurements are performed at wall conditions well above the Leidenfrost temperature. Different values of the Weber numbers corresponding to the bouncing and splashing regimes are tested. Comparisons between the heat flux removed from the wall and the sensible heat gained by the liquid allows estimating the heat flux related to liquid evaporation. Results reveal that the respective level of the droplet sensible heat and the heat lost due to liquid vaporization can vary significantly with the droplet sizes and the Weber number

Application of laser resonance scattering to the study of high-temperature plasma-wall interaction

International Nuclear Information System (INIS)

Maeda, Mitsuo; Muraoka, Katsunori; Hamamoto, Makoto; Akazaki, Masanori; Miyazoe, Yasushi

1981-01-01

Studies on laser resonance scattering and its application to the study of high-temperature plasma-wall interaction are reviewed. The application of dye laser beam to resonant scattering method has been developed. This method is able to detect low density atoms. The fluorescent photon counts can be estimated for a two-level system and a three-level system. The S/N ratio, Which is in close connection with the detection limit, has been estimated. The doppler effect due to the thermal motion of atoms is taken into consideration. The calibration of the absolute number of atoms is necessary. Tunable coherent light is used as the light source for resonance scattering method. This is able to excite atoms strongly and to increase the detection efficiency. As dye lasers, a N 2 laser, a YAG laser, and a KrF excimer laser have been studied. In VUV region, rare gas or rare gas halide lasers can be used. The strong output power can be expected when the resonance lines of atoms meet the synchronizing region of the excimer laser. The resonance scattering method is applied to the detection of impurity metal atoms in plasma. The studies of laser systems for the detection of hydrogen atoms are also in progress. (Kato, T.)

Characteristics of the magnetic wall reflection model on ion acceleration in gas-puff z pinch

International Nuclear Information System (INIS)

Nishio, M.; Takasugi, K.

2013-01-01

The magnetic wall reflection model was examined with the numerical simulation of the trajectory calculation of particles. This model is for the ions accelerated by some current-independent mechanism. The trajectory calculation showed angle dependency of highest velocities of accelerated particles. This characteristics is of the magnetic wall reflection model, not of the other current-independent acceleration mechanism. Thomson parabola measurements of accelerated ions produced in the gas-puff z-pinch experiments were carried out for the verification of the angle dependency. (author)

Study on Method of Ultrasonic Gas Temperature Measure Based on FPGA

Energy Technology Data Exchange (ETDEWEB)

Wen, S H; Xu, F R [Institute of Electrical Engineering, Yanshan University, Qinhuangdao, 066004 (China)

2006-10-15

It is always a problem to measure instantaneous temperature of high-temperature and high-pressure gas. There is difficulty for the conventional method of measuring temperature to measure quickly and exactly, and the measuring precision is low, the ability of anti-jamming is bad, etc. So the article introduces a method of measuring burning gas temperature using ultrasonic based on Field-Programmable Gate Array (FPGA). The mathematic model of measuring temperature is built with the relation of velocity of ultrasonic transmitting and gas Kelvin in the ideal gas. The temperature can be figured out by measuring the difference of ultrasonic frequency {delta}f. FPGA is introduced and a high-precision data acquisition system based on digital phase-shift technology is designed. The feasibility of proposed above is confirmed more by measuring pressure of burning gas timely. Experimental result demonstrates that the error is less than 12.. and the precision is heightened to 0.8%.

Generation and confinement of microwave gas-plasma in photonic dielectric microstructure.

Science.gov (United States)

Debord, B; Jamier, R; Gérôme, F; Leroy, O; Boisse-Laporte, C; Leprince, P; Alves, L L; Benabid, F

2013-10-21

We report on a self-guided microwave surface-wave induced generation of ~60 μm diameter and 6 cm-long column of argon-plasma confined in the core of a hollow-core photonic crystal fiber. At gas pressure of 1 mbar, the micro-confined plasma exhibits a stable transverse profile with a maximum gas-temperature as high as 1300 ± 200 K, and a wall-temperature as low as 500 K, and an electron density level of 10¹⁴ cm⁻³. The fiber guided fluorescence emission presents strong Ar⁺ spectral lines in the visible and near UV. Theory shows that the observed combination of relatively low wall-temperature and high ionisation rate in this strongly confined configuration is due to an unprecedentedly wide electrostatic space-charge field and the subsequent ion acceleration dominance in the plasma-to-gas power transfer.

Hardness of high-pressure high-temperature treated single-walled carbon nanotubes

International Nuclear Information System (INIS)

Kawasaki, S.; Nojima, Y.; Yokomae, T.; Okino, F.; Touhara, H.

2007-01-01

We have performed high-pressure high-temperature (HPHT) treatments of high quality single-walled carbon nanotubes (SWCNTs) over a wide pressure-temperature range up to 13 GPa-873 K and have investigated the hardness of the HPHT-treated SWCNTs using a nanoindentation technique. It was found that the hardness of the SWCNTs treated at pressures greater than 11 GPa and at temperatures higher than 773 K is about 10 times greater than that of the SWCNTs treated at low temperature. It was also found that the hardness change of the SWCNTs is related to the structural change by the HPHT treatments which was based on synchrotron X-ray diffraction measurements

Experimental study of slight temperature rise combustion in trapped vortex combustors for gas turbines

International Nuclear Information System (INIS)

Zhang, R.C.; Fan, W.J.; Xing, F.; Song, S.W.; Shi, Q.; Tian, G.H.; Tan, W.L.

2015-01-01

Interstage turbine combustion used for improving efficiency of gas turbine was a new type of combustion mode. Operating conditions and technical requirements for this type of combustor were different from those of traditional combustor. It was expected to achieve engineering application in both ground-based and aviation gas turbine in the near future. In this study, a number of modifications in a base design were applied and examined experimentally. The trapped-vortex combustion technology was adopted for flame stability under high velocity conditions, and the preheating-fuel injection technology was used to improve the atomization and evaporation performance of liquid fuel. The experimental results indicated that stable and efficient combustion with slight temperature-rise can be achieved under the high velocity conditions of combustor inlet. Under all experimental conditions, the excess air coefficients of ignition and lean blow-out were larger than 7 and 20, respectively; pollutant emission index of NO x and the maximum wall temperature were below 2.5 g/(kg fuel) and 1050 K, respectively. Moreover, the effects of fuel injection and overall configuration on the combustion characteristics were analyzed in detail. The number increase, area increase and depth increase of fuel injectors had different influences on the stability, combustion characteristic and temperature distribution. - Highlights: • The combustion mode of slight temperature-rise (200 K) was achieved. • Effect of fuel and air injection on stability characteristic was investigated. • Impact of overall configuration on combustion performance was analyzed. • The feasibility of scheme was determined.

Nonintrusive transceiver and method for characterizing temperature and velocity fields in a gas turbine combustor

Science.gov (United States)

DeSilva, Upul P.; Claussen, Heiko

2017-09-05

An acoustic transceiver is implemented for measuring acoustic properties of a gas in a turbine engine combustor. The transceiver housing defines a measurement chamber and has an opening adapted for attachment to a turbine engine combustor wall. The opening permits propagation of acoustic signals between the gas in the turbine engine combustor and gas in the measurement chamber. An acoustic sensor mounted to the housing receives acoustic signals propagating in the measurement chamber, and an acoustic transmitter mounted to the housing creates acoustic signals within the measurement chamber. An acoustic measurement system includes at least two such transceivers attached to a turbine engine combustor wall and connected to a controller.

Molecular dynamic simulation of Ar-Kr mixture across a rough walled nanochannel: Velocity and temperature profiles

International Nuclear Information System (INIS)

Pooja,; Ahluwalia, P. K.; Pathania, Y.

2015-01-01

This paper presents the results from a molecular dynamics simulation of mixture of argon and krypton in the Poiseuille flow across a rough walled nanochannel. The roughness effect on liquid nanoflows has recently drawn attention The computational software used for carrying out the molecular dynamics simulations is LAMMPS. The fluid flow takes place between two parallel plates and is bounded by horizontal rough walls in one direction and periodic boundary conditions are imposed in the other two directions. Each fluid atom interacts with other fluid atoms and wall atoms through Leenard-Jones (LJ) potential with a cut off distance of 5.0. To derive the flow a constant force is applied whose value is varied from 0.1 to 0.3 and velocity profiles and temperature profiles are noted for these values of forces. The velocity profile and temperature profiles are also looked at different channel widths of nanochannel and at different densities of mixture. The velocity profile and temperature profile of rough walled nanochannel are compared with that of smooth walled nanochannel and it is concluded that mean velocity increases with increase in channel width, force applied and decrease in density also with introduction of roughness in the walls of nanochannel mean velocity again increases and results also agree with the analytical solution of a Poiseuille flow

Influence of Gas-Liquid Interface on Temperature Wave of Pulsating Heat Pipe

Directory of Open Access Journals (Sweden)

Ying Zhang

2018-01-01

Full Text Available The influence of the interface on the amplitude and phase of the temperature wave and the relationship between the attenuation of the temperature wave and the gas-liquid two-phase physical parameters are studied during the operation of the pulsating heat pipe. The numerical simulation shows that the existence of the phase interface changes the direction of the temperature gradient during the propagation of the temperature wave, which increases the additional “thermal resistance.” The relative size of the gas-liquid two-phase thermal conductivity affects the propagation direction of heat flow at phase interface directly. The blockage of the gas plug causes hysteresis in the phase of the temperature wave, the relative size of the gas-liquid two-phase temperature coefficient will gradually increase the phase of the temperature wave, and the time when the heat flow reaches the peak value is also advanced. The attenuation of the temperature wave is almost irrelevant to the absolute value of the density, heat capacity, and thermal conductivity of the gas-liquid two phases, and the ratio of the thermal conductivity of the gas-liquid two phases is related. When the temperature of the heat pipe was changed, the difference of heat storage ability between gas and liquid will lead to the phenomenon of heat reflux and becomes more pronounced with the increases of the temperature wave.

Effects of Loading Rate on Gas Seepage and Temperature in Coal and Its Potential for Coal-Gas Disaster Early-Warning

Directory of Open Access Journals (Sweden)

Chong Zhang

2017-08-01

Full Text Available The seepage velocity and temperature externally manifest the changing structure, gas desorption and energy release that occurs in coal containing gas failure under loading. By using the system of coal containing gas failure under loading, this paper studies the law of seepage velocity and temperature under different loading rates and at 1.0 MPa confining pressure and 0.5 MPa gas pressure, and combined the on-site results of gas pressure and temperature. The results show that the stress directly affects the seepage velocity and temperature of coal containing gas, and the pressure and content of gas have the most sensitivity to mining stress. Although the temperature is not sensitive to mining stress, it has great correlation with mining stress. Seepage velocity has the characteristic of critically slowing down under loading. This is demonstrated by the variance increasing before the main failure of the samples. Therefore, the variance of seepage velocity with time and temperature can provide an early warning for coal containing gas failing and gas disasters in a coal mine.

Method for high temperature mercury capture from gas streams

Science.gov (United States)

Granite, Evan J [Wexford, PA; Pennline, Henry W [Bethel Park, PA

2006-04-25

A process to facilitate mercury extraction from high temperature flue/fuel gas via the use of metal sorbents which capture mercury at ambient and high temperatures. The spent sorbents can be regenerated after exposure to mercury. The metal sorbents can be used as pure metals (or combinations of metals) or dispersed on an inert support to increase surface area per gram of metal sorbent. Iridium and ruthenium are effective for mercury removal from flue and smelter gases. Palladium and platinum are effective for mercury removal from fuel gas (syngas). An iridium-platinum alloy is suitable for metal capture in many industrial effluent gas streams including highly corrosive gas streams.

High Temperature Gas-cooled Reactor Projected Markets and Scoping Economics

Energy Technology Data Exchange (ETDEWEB)

Larry Demick

2010-08-01

The NGNP Project has the objective of developing the high temperature gas-cooled reactor (HTGR) technology to supply high temperature process heat to industrial processes as a substitute for burning of fossil fuels, such as natural gas. Applications of the HTGR technology that have been evaluated by the NGNP Project for supply of process heat include supply of electricity, steam and high-temperature gas to a wide range of industrial processes, and production of hydrogen and oxygen for use in petrochemical, refining, coal to liquid fuels, chemical, and fertilizer plants.

Performance evaluation of Maxwell and Cercignani-Lampis gas-wall interaction models in the modeling of thermally driven rarefied gas transport

KAUST Repository

Liang, Tengfei

2013-07-16

A systematic study on the performance of two empirical gas-wall interaction models, the Maxwell model and the Cercignani-Lampis (CL) model, in the entire Knudsen range is conducted. The models are evaluated by examining the accuracy of key macroscopic quantities such as temperature, density, and pressure, in three benchmark thermal problems, namely the Fourier thermal problem, the Knudsen force problem, and the thermal transpiration problem. The reference solutions are obtained from a validated hybrid DSMC-MD algorithm developed in-house. It has been found that while both models predict temperature and density reasonably well in the Fourier thermal problem, the pressure profile obtained from Maxwell model exhibits a trend that opposes that from the reference solution. As a consequence, the Maxwell model is unable to predict the orientation change of the Knudsen force acting on a cold cylinder embedded in a hot cylindrical enclosure at a certain Knudsen number. In the simulation of the thermal transpiration coefficient, although all three models overestimate the coefficient, the coefficient obtained from CL model is the closest to the reference solution. The Maxwell model performs the worst. The cause of the overestimated coefficient is investigated and its link to the overly constrained correlation between the tangential momentum accommodation coefficient and the tangential energy accommodation coefficient inherent in the models is pointed out. Directions for further improvement of models are suggested.

Electron temperature and density measurement of tungsten inert gas arcs with Ar-He shielding gas mixture

Science.gov (United States)

Kühn-Kauffeldt, M.; Marques, J.-L.; Forster, G.; Schein, J.

2013-10-01

The diagnostics of atmospheric welding plasma is a well-established technology. In most cases the measurements are limited to processes using pure shielding gas. However in many applications shielding gas is a mixture of various components including metal vapor in gas metal arc welding (GMAW). Shielding gas mixtures are intentionally used for tungsten inert gas (TIG) welding in order to improve the welding performance. For example adding Helium to Argon shielding gas allows the weld geometry and porosity to be influenced. Yet thermal plasmas produced with gas mixtures or metal vapor still require further experimental investigation. In this work coherent Thomson scattering is used to measure electron temperature and density in these plasmas, since this technique allows independent measurements of electron and ion temperature. Here thermal plasmas generated by a TIG process with 50% Argon and 50% Helium shielding gas mixture have been investigated. Electron temperature and density measured by coherent Thomson scattering have been compared to the results of spectroscopic measurements of the plasma density using Stark broadening of the 696.5 nm Argon spectral line. Further investigations of MIG processes using Thomson scattering technique are planned.

Electron temperature and density measurement of tungsten inert gas arcs with Ar-He shielding gas mixture

International Nuclear Information System (INIS)

Kühn-Kauffeldt, M; Marques, J-L; Forster, G; Schein, J

2013-01-01

The diagnostics of atmospheric welding plasma is a well-established technology. In most cases the measurements are limited to processes using pure shielding gas. However in many applications shielding gas is a mixture of various components including metal vapor in gas metal arc welding (GMAW). Shielding gas mixtures are intentionally used for tungsten inert gas (TIG) welding in order to improve the welding performance. For example adding Helium to Argon shielding gas allows the weld geometry and porosity to be influenced. Yet thermal plasmas produced with gas mixtures or metal vapor still require further experimental investigation. In this work coherent Thomson scattering is used to measure electron temperature and density in these plasmas, since this technique allows independent measurements of electron and ion temperature. Here thermal plasmas generated by a TIG process with 50% Argon and 50% Helium shielding gas mixture have been investigated. Electron temperature and density measured by coherent Thomson scattering have been compared to the results of spectroscopic measurements of the plasma density using Stark broadening of the 696.5 nm Argon spectral line. Further investigations of MIG processes using Thomson scattering technique are planned

Determination of gas temperature in the plasmatron channel according to the known distribution of electronic temperature

Directory of Open Access Journals (Sweden)

Gerasimov Alexander V.

2013-01-01

Full Text Available An analytical method to calculate the temperature distribution of heavy particles in the channel of the plasma torch on the known distribution of the electronic temperature has been proposed. The results can be useful for a number of model calculations in determining the most effective conditions of gas blowing through the plasma torch with the purpose of heating the heavy component. This approach allows us to understand full details about the heating of cold gas, inpouring the plasma, and to estimate correctly the distribution of the gas temperature inside the channel.

Structural instabilities of high temperature alloys and their use in advanced high temperature gas cooled reactors

International Nuclear Information System (INIS)

Schuster, H.; Ennis, P.J.; Nickel, H.; Czyrska-Filemonowicz, A.

1989-01-01

High-temperature, iron-nickel and nickel based alloys are the candidate heat exchanger materials for advanced high temperature gas-cooled reactors supplying process heat for coal gasification, where operation temperatures can reach 850-950 deg. C and service lives of more than 100,000 h are necessary. In the present paper, typical examples of structural changes which occur in two representative alloys (Alloy 800 H, Fe-32Ni-20Cr and Alloy 617, Ni-22Cr-12Co-9Mo-1Al) during high temperature exposure will be given and the effects on the creep rupture properties discussed. At service temperatures, precipitation of carbides occurs which has a significant effect on the creep behaviour, especially in the early stages of creep when the precipitate particles are very fine. During coarsening of the carbides, carbides at grain boundaries restrict grain boundary sliding which retards the development of creep damage. In the service environments, enhanced carbide precipitation may occur due to the ingress of carbon from the environment (carburization). Although the creep rate is not adversely affected, the ductility of the carburized material at low and intermediate temperatures is very low. During simulated service exposures, the formation of surface corrosion scales, the precipitation of carbides and the formation of internal oxides below the surface leads to depletion of the matrix in the alloying elements involved in the corrosion processes. In thin-walled tubes the depletion of Cr due to Cr 2 O 3 formation on the surface can lead to a loss of creep strength. An additional depletion effect resulting from environmental-metal reactions is the loss of carbon (decarburization) which may occur in specific environments. The compositions of the cooling gases which decarburize the material have been determined; they are to be avoided during reactor operation

Laminar free convection in a vertical tube with constant wall temperature considering the variation of fluid properties

International Nuclear Information System (INIS)

Senna, J.G.

1981-01-01

A model to analyze Laminar Free convection with variable properties in the entrance of a vertical open tube with constant wall temperature and for one Prandtl number (0.7), is studied. The velocity and temperature profiles are determined by finite difference methods for different rates of wall to ambient temperatures and different values of the velocity in the entrance of the tube. The results will be compared with those obtained in the same problem with constant properties. (Author) [pt

Laminar free convection with variable fluid properties in vertical ducts having uniform wall temperature

International Nuclear Information System (INIS)

Aihara, Toshio; Maruyama, Shigenao; Choi, Jun-Seop.

1985-01-01

Recently, the research on free convection in vertical ducts has become active again concerning the problem of cooling in nuclear reactor accidents and the cooling of electronic equipment. Generally, in the convection heat transfer in ducts, when the wall temperature is high, the fluid temperature in the ducts conspicuously changes, accordingly, the temperature dependence of the properties cannot be neglected. In this study, about the laminar free convection in parallel plates and a circular pipe having uniform wall temperature, the numerical analysis taking the temperature dependence of all properties into account was carried out, thus the effect of the temperature dependence of properties exerted on free convection heat transfer was clarified, and the relation to the solution in constant properties was examined. Moreover, by introducing a new representative dimension, it was attempted to express mean heat transfer coefficient which is independent of the form of ducts in unified way. The mean Nusselt number of the constant property solution using entrance pressure condition agreed very well with the exact numerical solution. (Kako, I.)

Influence of the thermal boundary conditions on the flow and the isotope separation of a gas centrifuge

Energy Technology Data Exchange (ETDEWEB)

Novelli, P.

1981-11-01

The axisymmetric steady gas flow in a so called thermally driven ultracentrifuge at total reflux and its /sup 235/UF/sub 6/-/sup 238/UF/sub 6/- separating characteristics are treated numerically. The top and the bottom end-caps are thermally conducting and kept at temperatures generally depending on radius. Regarding the side-wall temperature conditions, three cases will be considered: (1) insulated side-wall; (2) side-wall at constant temperature; (3) linear temperature profile continuously joining the end-plate temperatures. 20 figures, 2 tables.

Oxidation of ethene in a wall-cooled packed-bed reactor

NARCIS (Netherlands)

Schouten, E.P.S.; Borman, P.C.; Westerterp, K.R.

1994-01-01

The selective oxidation of ethene over a silver on α-alumina catalyst was studied in a pilot plant with a wall-cooled tubular packed bed reactor. Gas and solid temperatures in the catalyst bed were measured at different axial and radial positions as well as concentrations at different axial

Laparoscopic cholecystectomy using abdominal wall retraction. Hemodynamics and gas exchange, a comparison with conventional pneumoperitoneum

NARCIS (Netherlands)

Meijer, D. W.; Rademaker, B. P.; Schlooz, S.; Bemelman, W. A.; de Wit, L. T.; Bannenberg, J. J.; Stijnen, T.; Gouma, D. F.

1997-01-01

BACKGROUND: Disadvantages related to CO2 pneumoperitoneum have led to development of the abdominal wall retractor (AWR), a device designed to facilitate laparoscopic surgery without conventional pneumoperitoneum (15 mmHg CO2). We investigated the effects of the AWR on hemodynamics and gas exchange

In situ gas temperature measurements by UV-absorption spectroscopy

DEFF Research Database (Denmark)

Fateev, Alexander; Clausen, Sønnik

2009-01-01

The absorption spectrum of the NO A(2)Sigma(+) uniform and stable gas temperatures over a 0.533 m path....... The accuracy of both methods is discussed. Validation of the classical Lambert-Beer law has been demonstrated at NO concentrations up to 500 ppm and gas temperatures up to 1,500 degrees C over an optical absorption path length of 0.533 m....

Reduced one-body density matrix of Tonks–Girardeau gas at finite temperature

International Nuclear Information System (INIS)

Fu Xiao-Chen; Hao Ya-Jiang

2015-01-01

With thermal Bose–Fermi mapping method, we investigate the Tonks–Girardeau gas at finite temperature. It is shown that at low temperature, the Tonks gas displays the Fermi-like density profiles, and with the increase in temperature, the Tonks gas distributes in wider region. The reduced one-body density matrix is diagonal dominant in the whole temperature region, and the off-diagonal elements shall vanish rapidly with the deviation from the diagonal part at high temperature. (paper)

A low-temperature (4-300K) constant volume gas thermometer

International Nuclear Information System (INIS)

Combarieu, A. de

1976-01-01

A constant volume gas thermometer was built to calibrate the various secondary thermometers used at low temperature. This gas thermometer is placed in a cryostat where any stable temperature between 4 and 300K may be obtained. The principle is outlined, then the gas thermometer and its auxiliary equipment are briefly described; the corrections to be applied to the results are given and a table shows the values obtained [fr

Experimental optimization of temperature distribution in the hot-gas duct through the installation of internals in the hot-gas plenum of a high-temperature reactor

International Nuclear Information System (INIS)

Henssen, J.; Mauersberger, R.

1990-01-01

The flow conditions in the hot-gas plenum and in the adjacent hot-gas ducts and hot-gas pipes for the high-temperature reactor project PNP-1000 (nuclear process heat project for 1000 MW thermal output) have been examined experimentally. The experiments were performed in a closed loop in which the flow model to be analyzed, representing a 60deg sector of the core bottom of the PNP-1000 with connecting hot-gas piping and diverting arrangements, was installed. The model scale was approx. 1:5.6. The temperature and flow velocity distribution in the hot-gas duct was registered by means of 14 dual hot-wire flowmeters. Through structural changes and/or the installation of internals into the hot-gas plenum of the core bottom offering little flow resistance coolant gas temperature differentials produced in the core could be reduced to such an extent that a degree of mixture amounting to over 80% was achieved at the entrance of the connected heat exchanger systems. Thereby the desired goal of an adequate degree of mixture of the hot gas involving an acceptable pressure loss was reached. (orig.)

Optimized Feature Extraction for Temperature-Modulated Gas Sensors

Directory of Open Access Journals (Sweden)

Alexander Vergara

2009-01-01

Full Text Available One of the most serious limitations to the practical utilization of solid-state gas sensors is the drift of their signal. Even if drift is rooted in the chemical and physical processes occurring in the sensor, improved signal processing is generally considered as a methodology to increase sensors stability. Several studies evidenced the augmented stability of time variable signals elicited by the modulation of either the gas concentration or the operating temperature. Furthermore, when time-variable signals are used, the extraction of features can be accomplished in shorter time with respect to the time necessary to calculate the usual features defined in steady-state conditions. In this paper, we discuss the stability properties of distinct dynamic features using an array of metal oxide semiconductors gas sensors whose working temperature is modulated with optimized multisinusoidal signals. Experiments were aimed at measuring the dispersion of sensors features in repeated sequences of a limited number of experimental conditions. Results evidenced that the features extracted during the temperature modulation reduce the multidimensional data dispersion among repeated measurements. In particular, the Energy Signal Vector provided an almost constant classification rate along the time with respect to the temperature modulation.

Temperature dependence of the particle/gas partition coefficient: An application to predict indoor gas-phase concentrations of semi-volatile organic compounds

Energy Technology Data Exchange (ETDEWEB)

Wei, Wenjuan, E-mail: Wenjuan.Wei@cstb.fr [University of Paris-Est, Scientific and Technical Center for Building (CSTB), Health and Comfort Department, French Indoor Air Quality Observatory (OQAI), 84 Avenue Jean Jaurès, Champs sur Marne, 77447 Marne la Vallée Cedex 2 (France); Mandin, Corinne [University of Paris-Est, Scientific and Technical Center for Building (CSTB), Health and Comfort Department, French Indoor Air Quality Observatory (OQAI), 84 Avenue Jean Jaurès, Champs sur Marne, 77447 Marne la Vallée Cedex 2 (France); INSERM-U1085, Irset-Research Institute for Environmental and Occupational Health, Rennes (France); LERES-Environment and Health Research Laboratory (Irset and EHESP Technologic Platform), Rennes (France); Blanchard, Olivier [EHESP-School of Public Health, Sorbonne Paris Cité, Rennes (France); INSERM-U1085, Irset-Research Institute for Environmental and Occupational Health, Rennes (France); Mercier, Fabien [EHESP-School of Public Health, Sorbonne Paris Cité, Rennes (France); LERES-Environment and Health Research Laboratory (Irset and EHESP Technologic Platform), Rennes (France); INSERM-U1085, Irset-Research Institute for Environmental and Occupational Health, Rennes (France); Pelletier, Maud [EHESP-School of Public Health, Sorbonne Paris Cité, Rennes (France); INSERM-U1085, Irset-Research Institute for Environmental and Occupational Health, Rennes (France); Le Bot, Barbara [EHESP-School of Public Health, Sorbonne Paris Cité, Rennes (France); LERES-Environment and Health Research Laboratory (Irset and EHESP Technologic Platform), Rennes (France); INSERM-U1085, Irset-Research Institute for Environmental and Occupational Health, Rennes (France); and others

2016-09-01

The indoor gas-phase concentrations of semi-volatile organic compounds (SVOCs) can be predicted from their respective concentrations in airborne particles by applying the particle/gas partitioning equilibrium. The temperature used for partitioning is often set to 25 °C. However, indoor temperatures frequently differ from this reference value. This assumption may result in errors in the predicted equilibrium gas-phase SVOC concentrations. To improve the prediction model, the temperature dependence of the particle/gas partition coefficient must be addressed. In this paper, a theoretical relationship between the particle/gas partition coefficient and temperature was developed based on the SVOC absorptive mechanism. The SVOC particle/gas partition coefficients predicted by employing the derived theoretical relationship agree well with the experimental data retrieved from the literature (R > 0.93). The influence of temperature on the equilibrium gas-phase SVOC concentration was quantified by a dimensionless analysis of the derived relationship between the SVOC particle/gas partition coefficient and temperature. The predicted equilibrium gas-phase SVOC concentration decreased by between 31% and 53% when the temperature was lowered by 6 °C, while it increased by up to 750% when the indoor temperature increased from 15 °C to 30 °C. - Highlights: • A theoretical relationship between K{sub p} and temperature was developed. • The relationship was based on the SVOC absorptive mechanism. • The temperature impact was quantified by a dimensionless analysis.

Two-branch Gas Experiments for Hot Gas Mixing of HTR-PM

International Nuclear Information System (INIS)

Zhou Yangping; Hao Pengefei; He Heng; Li Fu; Shi Lei

2014-01-01

A model experiment is proposed to investigate the hot gas mixing efficiency of HTR-PM reactor outlet. The test facility is introduced which is set at a scale of 1:2.5 comparing with the design of thermal mixing structure at HTR-PM reactor outlet. The test facility using air as its flow media includes inlet pipe system, electric heaters, main body of test facility, hot gas duct, exhaust pipe system and I&C system. Two-branch gas experiments are conducted on the test facility and the values of thermal-fluid parameters are collected and analyzed which include the temperature, pressure and velocity of the flow as well as the temperature of the tube wall. The analysis result shows the mixing efficiency is higher than the requirement of thermal mixing by steam generator even with conservative assumption which indicates that the design of hog gas mixing structure of HTR-PM fulfills the requirement for thermal mixing at two-branch working conditions. (author)

The effect of pressurization path on high pressure gas forming of Ti-3Al-2.5V at elevated temperature

Directory of Open Access Journals (Sweden)

Liu Gang

2015-01-01

Full Text Available High pressure gas forming is a tubular component forming technology with pressurized gas at elevated temperature, based on QPF, HMGF and Hydroforming. This process can be used to form tube blank at lower temperatures with high energy efficiency and also at higher strain rates. With Ti-3Al-2.5V Ti-alloy tube, the potential of HPGF was studied further through experiments at the elevated temperatures of 650 ∘C and 700 ∘C. In order to know the formability of the Ti-alloy tube, tensile tests were also carried out. The results show that: at the temperatures of 650 ∘C and 700 ∘C, the flow curves exhibit the power-law constitutive relation until peak stress is reached and the deformability is suitable for the HPGF process of Ti-3Al-2.5V alloy tube. The effects of pressurization path on the corner filling process and thickness profile are obvious. The high pressure inflow process can result in temperature difference between the straight wall area and corner area, which makes the thickness profile special. Besides, with the stepped pressurization path, the more constant filling rate and better thickness profile can be obtained.

Determining noncondensible gas fractions at elevated temperatures and pressures using wet and dry bulb temperature measurements

International Nuclear Information System (INIS)

Griffith, P.; Bowman, J.

1987-01-01

The work reported in this note was undertaken to provide a method of determining the noncondensible gas fractions in a steam-gas mixture such as might be found in large reactor safety experiment like LOFT. In essence, the method used involves measuring the wet and dry bulb temperatures and using an algorithm, in place of the psychometric chart, to determine the partial pressure of the noncondensible gas in the mixture. In accomplishing this, the authors did the following: (1) extended the use of wet and dry-bulb temperature readings to determine mixture composition up to a temperature of 589 K and a pressure of 4.13 x 10 6 Pa. (2) developed an algorithm to reduce the data (3) found which materials would survive those temperatures

Laboratory study on the high-temperature capture of HCl gas by dry-injection of calcium-based sorbents.

Science.gov (United States)

Shemwell, B; Levendis, Y A; Simons, G A

2001-01-01

This is a laboratory study on the reduction of combustion-generated hydrochloric acid (HCl) emissions by in-furnace dry-injection of calcium-based sorbents. HCl is a hazardous gaseous pollutant emitted in significant quantities by municipal and hazardous waste incinerators, coal-fired power plants, and other industrial furnaces. Experiments were conducted in a laboratory furnace at gas temperatures of 600-1000 degrees C. HCl gas diluted with N2, and sorbent powders fluidized in a stream of air were introduced into the furnace concurrently. Chlorination of the sorbents occurred in the hot zone of the furnace at gas residence times approximately 1 s. The sorbents chosen for these experiments were calcium formate (CF), calcium magnesium acetate (CMA), calcium propionate (CP), calcium oxide (CX), and calcium carbonate (CC). Upon release of organic volatiles, sorbents calcine to CaO at approximately 700 degrees C, and react with the HCl according to the reaction CaO + 2HCl CaCl2 + H2O. At the lowest temperature case examined herein, 600 degrees C, direct reaction of HCl with CaCO3 may also be expected. The effectiveness of the sorbents to capture HCl was interpreted using the "pore tree" mathematical model for heterogeneous diffusion reactions. Results show that the thin-walled, highly porous cenospheres formed from the pyrolysis and calcination of CF, CMA, and CP exhibited high relative calcium utilization at the upper temperatures of this study. Relative utilizations under these conditions reached 80%. The less costly low-porosity sorbents, calcium carbonate and calcium oxide also performed well. Calcium carbonate reached a relative utilization of 54% in the mid-temperature range, while the calcium oxide reached an 80% relative utilization at the lowest temperature examined. The data matched theoretical predictions of sorbent utilization using the mathematical model, with activation energy and pre-exponential factors for the calcination reaction of 17,000 K and 300

Low-foot rugby hohlraum experiments on the NIF: Wall-gas mix and a connection with missing x-ray drive energy?

Science.gov (United States)

Amendt, Peter; Ross, J. Steven; Schneider, Marilyn; Jones, Oggie; Milovich, Jose; Moody, John

2014-10-01

Rugby-shaped hohlraums on the NIF have shown strong symmetry anomalies when simulated with the high-flux model. The wall-gas interface is Rayleigh-Taylor unstable and may lead to the formation of a late-time mix layer that impedes inner- cone propagation, resulting in a drive asymmetry on the capsule. Due to the rugby curvature near the laser entrance hole, the effect of mix may be more pronounced than in cylinders. At the same time a persistent pattern of 15--25% missing energy has been inferred in gas-filled hohlraums (ρ >= 0 . 96 mg/cc). A possible physical connection between formation of a mix layer and the plasma adiabatic lapse rate, where a temperature-gradient reversal is predicted to occur, is explored. Such a profile reversal, in turn, hinders electron conduction to the dense (ρ > 0 . 2 g/cc) Au region responsible for ~900 eV drive x-ray emission, leading to a hotter coronal plasma and reduced hohlraum efficiency. Remedial measures for recovering the loss in hohlraum efficiency through the use of higher-Z gas fills are explored. Prepared by LLNL under Contract DE-AC52-07NA27344.

Elevated temperature and high pressure large helium gas loop

International Nuclear Information System (INIS)

Sakasai, Minoru; Midoriyama, Shigeru; Miyata, Toyohiko; Nakase, Tsuyoshi; Izaki, Makoto

1979-01-01

The development of high temperature gas-cooled reactors especially aiming at the multi-purpose utilization of nuclear heat energy is carried out actively in Japan and West Germany. In Japan, the experimental HTGR of 50 MWt and 1000 deg C outlet temperature is being developed by Japan Atomic Energy Research Institute and others since 1969, and the development of direct iron-making technology utilizing high temperature reducing gas was started in 1973 as the large project of Ministry of Internalional Trade and Industry. Kawasaki Heavy Industries, Ltd., Has taken part in these development projects, and has developed many softwares for nuclear heat design, system design and safety design of nuclear reactor system and heat utilization system. In hardwares also, efforts have been exerted to develop the technologies of design and manufacture of high temperature machinery and equipments. The high temperature, high pressure, large helium gas loop is under construction in the technical research institute of the company, and it is expected to be completed in December, 1979. The tests planned are that of proving the dynamic performances of the loop and its machinery and equipments and the verification of analysis codes. The loop is composed of the main circulation system, the objects of testing, the helium gas purifying system, the helium supplying and evacuating system, instruments and others. (Kako, I.)

High temperature meson propagators with domain-wall quarks

International Nuclear Information System (INIS)

Lagae, J.-F.; Sinclair, D. K.

1999-01-01

We study the chiral properties of domain-wall quarks at high temperatures on an ensemble of quenched configurations. Low lying eigenmodes of the Dirac operator are calculated and used to check the extent to which the Atiyah-Singer index theorem is obeyed on lattices with finite N 5 . We calculate the connected and disconnected screening propagators for the lowest mass scalar and pseudoscalar mesons in the sectors of different topological charge and note that they behave as expected. Separating out the would-be zero eigenmodes enables us to accurately estimate the disconnected propagators with far less effort than would be needed otherwise

High temperature meson propagators with domain-wall quarks

International Nuclear Information System (INIS)

Lagaee, J.-F.; Sinclair, D.K.

2000-01-01

We study the chiral properties of domain-wall quarks at high temperatures on an ensemble of quenched configurations. Low lying eigenmodes of the Dirac operator are calculated and used to check the extent to which the Atiyah-Singer index theorem is obeyed on lattices with finite N 5 . We calculate the connected and disconnected screening propagators for the lowest mass scalar and pseudoscalar mesons in the sectors of different topological charge and note that they behave as expected. Separating out the would-be zero eigenmodes enables us to accurately estimate the disconnected propagators with far less effort than would be needed otherwise

Utilization of multi-purpose high temperature gas-cooled reactors

International Nuclear Information System (INIS)

Kawada, Osamu; Onuki, Yoshiaki; Wasaoka, Takeshi.

1974-01-01

Concerning the utilization of multi-purpose high temperature gas-cooled reactors, the electric power generation with gas turbines is described: features of HTR-He gas turbine power plants; the state of development of He gas turbines; and combined cycle with gas turbines and steam turbines. The features of gas turbines concern heat dissipation into the environment and the mode of load operation. Outstanding work in the development of He gas turbines is that in Hochtemperatur Helium-Turbine Project in West Germany. The power generation with combined gas turbines and steam turbines appears to be superior to that with gas turbines alone. (Mori, K.)

On compressible flow in a gas centrifuge and its effect on the maximum separative power

NARCIS (Netherlands)

Brouwers, J.J.H.

1978-01-01

The gas circulation in a gas centrifuge due to temperature differences, differential rotation and injection, and removal of fluid at the ends, as well as due to temperature gradients at the cylinder wall, is treated analytically. The motion consists of a small perturbation on a state of isothermal

Temperature Control of Gas Chromatograph Based on Switched Delayed System Techniques

Directory of Open Access Journals (Sweden)

Xiao-Liang Wang

2014-01-01

Full Text Available We address the temperature control problem of the gas chromatograph. We model the temperature control system of the gas chromatograph into a switched delayed system and analyze the stability by common Lyapunov functional technique. The PI controller parameters can be given based on the proposed linear matrix inequalities (LMIs condition and the designed controller can make the temperature of gas chromatograph track the reference signal asymptotically. An experiment is given to illustrate the effectiveness of the stability criterion.

Conditions for lowering the flue gas temperature; Foerutsaettning foer saenkning av roekgastemperatur

Energy Technology Data Exchange (ETDEWEB)

Nordling, Magnus

2012-02-15

In heat and power production, the efficiency of the power plant increases the larger share of heat from the flue gas that is converted to power. However, this also implies that the temperature of the heat exchanging surfaces is lowered. If the temperature is lowered to a temperature below the dew point of the flue gas, this would result in condensation of the gas, which in turn elevates the risk of serious corrosion attack on the surfaces where condensation occurs. Thus, it is important to determine the dew point temperature. One way of determining the dew point temperature is to use data on composition of the fuel together with operation parameters of the plant, thus calculating the dew point temperature. However, this calculation of the dew point is not so reliable, especially if hygroscopic salts are present. Therefore, for safety reasons, the temperature of the flue gas is kept well above the dew point temperature. This results in lowered over-all efficiency of the plant. It could also be expected that for a certain plant, some construction materials under certain operation conditions would have corrosion characteristics that may allow condensation on the surface without severe and unpredictable corrosion attack. However, by only using operation parameters and fuel composition, it is even harder to predict the composition of the condensate at different operation temperatures than to calculate the dew point temperature. If the dew point temperature was known with a greater certainty, the temperature of the flue gas could be kept lower, just above the estimated value of the dew point, without any increased risk for condensation. If, in addition, also the resulting composition of the condensate at different temperatures below the dew point is known, it can be predicted if the construction materials of the flue gas channel were compatible with the formed condensate. If they are compatible, the flue gas temperature can be further lowered from the dew point

Utilizing the response patterns of a temperature modulated chemoresistive gas sensor for gas diagnosis

International Nuclear Information System (INIS)

Amini, Amir; Ghafarinia, Vahid

2011-01-01

The observed features in the temporal response patterns of a temperature-modulated chemoresistive gas sensor were used for gas diagnosis. The patterns were recorded for clean air and air contaminated with different levels of some volatile organic compounds while a staircase heating voltage waveform had been applied to the microheater of a tin oxide gas sensor that modulated its operating temperature. Combining the steady-state and transient parameters of the recorded responses in the 50-400 deg. C range resulted in discriminatory feature vectors which were utilized for contaminant classification. The information content of these feature vectors was proved sufficient for discrimination of methanol, ethanol, 1-butanol, and acetone contaminations in a wide concentration range.

Utilizing the response patterns of a temperature modulated chemoresistive gas sensor for gas diagnosis

Energy Technology Data Exchange (ETDEWEB)

Amini, Amir [Jannatabad College, Sama Organization, Islamic Azad University, Tehran (Iran, Islamic Republic of); Ghafarinia, Vahid, E-mail: amir.amini.elec@gmail.com, E-mail: ghafarinia@ee.kntu.ac.ir [Electrical Engineering Department, K. N. Toosi University of Technology, Tehran (Iran, Islamic Republic of)

2011-02-15

The observed features in the temporal response patterns of a temperature-modulated chemoresistive gas sensor were used for gas diagnosis. The patterns were recorded for clean air and air contaminated with different levels of some volatile organic compounds while a staircase heating voltage waveform had been applied to the microheater of a tin oxide gas sensor that modulated its operating temperature. Combining the steady-state and transient parameters of the recorded responses in the 50-400 deg. C range resulted in discriminatory feature vectors which were utilized for contaminant classification. The information content of these feature vectors was proved sufficient for discrimination of methanol, ethanol, 1-butanol, and acetone contaminations in a wide concentration range.

An experimental investigation of fluid flow and wall temperature distributions in an automotive headlight

International Nuclear Information System (INIS)

Sousa, J.M.M.; Vogado, J.; Costa, M.; Bensler, H.; Freek, C.; Heath, D.

2005-01-01

Detailed measurements of wall temperatures and fluid flow velocities inside an automotive headlight with venting apertures are presented. Thermocouples have been used to characterize the temperature distributions in the walls of the reflectors under transient and steady operating conditions. Quantification of the markedly three-dimensional flow field inside the headlight cavities was achieved through the use of laser-Doppler velocimetry for the latter condition only. Significant thermal stratification occurs in the headlight cavities. The regime corresponding to steady operating conditions is characterized by the development of a vortex-dominated flow. The interaction of the main vortex flow with the stream of colder fluid entering the enclosed volume through the venting aperture contributes significantly to increase the complexity of the basic flow pattern. Globally, the results have improved the understanding of the temperature loads and fluid flow phenomena inside a modern automotive headlight

Influence of Slip Condition on Unsteady Free Convection Flow of Viscous Fluid with Ramped Wall Temperature

Directory of Open Access Journals (Sweden)

Sami Ul Haq

2015-01-01

Full Text Available The objective of this study is to explore the influence of wall slip condition on a free convection flow of an incompressible viscous fluid with heat transfer and ramped wall temperature. Exact solution of the problem is obtained by using Laplace transform technique. Graphical results to see the effects of Prandtl number Pr, time t, and slip parameter η on velocity and skin friction for the case of ramped and constant temperature of the plate are provided and discussed.

Spray-Wall Impingement of Diesel-CNG Dual Fuel Jet using Schlieren Imaging Technique

Directory of Open Access Journals (Sweden)

Ismael Mhadi Abaker

2014-07-01

Full Text Available Natural gas is a low cost fuel with high availability in nature. However, it cannot be used by itself in conventional diesel engines due to its low flame speed and high ignition temperature. The addition of a secondary fuel to enhance the mixture formation and combustion process facilitate its wider use as an alternative fuel. An experimental study was performed to investigate the diesel-CNG dual fuel jet-wall impingement. A constant volume optical chamber was designed to facilitate maximum optical access for the study of the jet-wall impingement at different injection pressures, temperatures and injector-wall distances. The bottom plate of the test rig was made of aluminum (piston material and it was heated up to 500 K at ambient pressure. An injector driver was used to control the single-hole nozzle diesel injector combined with a natural gas injector. The injection timing of both injectors was synchronized with a camera trigger. The jet-wall impingement of diesel and diesel-CNG dual fuel jets was recorded with a high speed camera using Schlieren imaging technique and associated image processing software. The measurements of the jet radial penetration were higher in diesel-CNG dual fuel while the jet height travel along were higher in the case of diesel single fuel.

Moderate temperature gas purification system: Application to high calorific coal-derived fuel

Energy Technology Data Exchange (ETDEWEB)

Kobayashi, M.; Shirai, H.; Nunokawa, M. [Central Research Institute of Electric Power Industry, Kanagawa (Japan)

2008-01-15

Simultaneous removal of dust, alkaline and alkaline-earth metals, halides and sulfur compounds is required to enlarge application of coal-derived gas to the high-temperature fuel cells and the fuel synthesis through chemical processing. Because high calorific fuel gas, such as oxygen-blown coal gas, has high carbon monoxide content, high-temperature (above 450{sup o}C) gas purification system is always subjected to the carbon deposition. We suggest moderate temperature (around 300{sup o}C) operation of the gas purification system to avoid the harmful disproportionation reaction and efficient removal of the various contaminants. Because the reaction rate is predominant to the performance of contaminant removal in the moderate temperature gas purification system, we evaluated the chemical removal processes; performance of the removal processes for halides and sulfur compounds was experimentally evaluated. The halide removal process with sodium aluminate sorbent had potential performance at around 300{sup o}C. The sulfur removal process with zinc ferrite sorbent was also applicable to the temperature range, though the reaction kinetics of the sorbent is essential to be approved.

Effect of wall impingement on ambient gas entrainment, fuel evaporation and mixture formation of diesel spray

Energy Technology Data Exchange (ETDEWEB)

Nishida, Keiya [Department of Mechanical Physics Engineering, University of Hiroshima (Japan); Matsumoto, Yuhei; Zhang, Wu [Mazda Motor Corp. (Japan); Gao, Jian [University of Wisconsin (United States); Moon, Seoksu [Argonne National Laboratory (United States)

2010-07-01

In the energy sector, with the implementation of stringent regulations on combustion emissions and the depletion of conventional fuels, there is a pressing need to improve the performance of engines. The purpose of this paper is to determine the impact of wall impingement on several characteristics of diesel spray. Experiments were carried out with both a small and a large amount of diesel spray injected and ambient gas entrainment, fuel evaporation and mixture formation were evaluated using an LAS optical system. Results showed that wall impingement has the same effects for small or large amounts of diesel spray injected; these are: a larger volume spray after the impingement and a smaller volume after it, the suppression of ambient gas entrainment and fuel evaporation, and the shift of the PDF peak of the vapor equivalent ratio. This study provided useful information but further work is needed to address the remaining issues.

Effect of wall wettability on flow characteristics of gas-liquid two-phase flow

International Nuclear Information System (INIS)

Uematsu, Junichi; Abe, Kazuya; Hazuku, Tatsuya; Takamasa, Tomoji; Hibiki, Takashi

2007-01-01

To evaluate the effect of surface wettability in pipe wall on flow characteristics in a vertical upward gas-liquid to-phase flow, visualization study was performed using three test pipes, namely an acrylic pipe, a hydrophilic pipe, a hydrophobic pipe. Such basic flow characteristics as flow patterns and void fraction were investigated in these three pipes. In the hydrophilic pipe, the slug flow-to-churn flow transition boundary was shifted to higher gas velocity condition at a given liquid velocity, whereas the churn flow-to-annular flow transition boundary was shifted to lower gas velocity condition at a given liquid velocity. In the hydrophobic pipe, the inverted-churn flow regime was observed in the region where the churn flow regime was observed in the acrylic pipe, whereas the droplet flow regime was observed in the region where the annular flow regime was observed in the acrylic pipe. At high-gas flow rate condition, the mean void fraction in the hydrophobic pipe took relatively higher value to that in the acrylic pipe. (author)

Poiseuille, thermal transpiration and Couette flows of a rarefied gas between plane parallel walls with nonuniform surface properties in the transverse direction and their reciprocity relations

Science.gov (United States)

Doi, Toshiyuki

2018-04-01

Slow flows of a rarefied gas between two plane parallel walls with nonuniform surface properties are studied based on kinetic theory. It is assumed that one wall is a diffuse reflection boundary and the other wall is a Maxwell-type boundary whose accommodation coefficient varies periodically in the direction perpendicular to the flow. The time-independent Poiseuille, thermal transpiration and Couette flows are considered. The flow behavior is numerically studied based on the linearized Bhatnagar-Gross-Krook-Welander model of the Boltzmann equation. The flow field, the mass and heat flow rates in the gas, and the tangential force acting on the wall surface are studied over a wide range of the gas rarefaction degree and the parameters characterizing the distribution of the accommodation coefficient. The locally convex velocity distribution is observed in Couette flow of a highly rarefied gas, similarly to Poiseuille flow and thermal transpiration. The reciprocity relations are numerically confirmed over a wide range of the flow parameters.

A study of silver behavior in Gas-turbine High Temperature Gas-cooled Reactor

International Nuclear Information System (INIS)

Sawa, Kazuhiro; Tanaka, Toshiyuki

1995-11-01

A Gas-turbine High Temperature Gas-cooled Reactor (GT-HTGR) is one of the promising reactor systems of future HTGRs. In the design of GT-HTGR, behavior of fission products, especially of silver, is considered to be important from the view point of maintenance of gas-turbine. A study of silver behavior in the GT-HTGR was carried out based on current knowledge. The purposes of this study were to determine an importance of the silver problem quantitatively, countermeasures to the problem and items of future research and development which will be needed. In this study, inventory, fractional release from fuel, plateout in the primary circuit and radiation dose were evaluated, respectively. Based on this study, it is predicted that gamma-ray from plateout silver in gas-turbine system contributes about a half of total radiation dose after reactor shutdown. In future, more detail data for silver release from fuel, plateout behavior, etc. using the High Temperature Engineering Test Reactor (HTTR), for example, will be needed to carry out reasonable design. (author)

Numerical study on influences of bed resettling, breeding zone orientation, and purge gas on temperatures in solid breeders

Energy Technology Data Exchange (ETDEWEB)

Van Lew, Jon T., E-mail: jtvanlew@fusion.ucla.edu; Ying, Alice; Abdou, Mohamed

2016-11-01

Highlights: • Volume-conserving pebble fragmentation model in DEM to study thermomechanical responses to crushed pebbles in ensembles. • Parametric studies of ITER-relevant pebble beds with coupled CFD-DEM models. • Finding breeder temperatures are complex functions of orientation, fragmentation size, and packing fraction. • Recommendations of breeder unit orientation are given in terms of material selection. - Abstract: We apply coupled computational fluid dynamics and discrete element method (CFD-DEM) modeling tools with new numerical implementations of pebble fragmentation to study the combined effects of granular crushing and ensemble restructuring, granular fragment size, and initial packing for different breeder volume configurations. In typical solid breeder modules, heat removal from beds relies on maintaining pebble–pebble and pebble–wall contact integrity. However, contact is disrupted when an ensemble responds to individually crushed pebbles. Furthermore, restructuring of metastable packings after crushing events are, in part, dependent on gravity forces acting upon the pebbles. We investigate two representative pebble bed configurations under constant volumetric heat sources; modeling heat removed from beds via inter-particle conduction, purge gas convection, and contact between pebble beds and containers. In one configuration, heat is removed from at walls oriented parallel to the gravity vector (no gap formation possible); in the second, heat is removed at walls perpendicular to gravity, allowing for the possibility of gap formation between bed and wall. Judging beds on increase in maximum temperatures as a function of crushed pebble amount, we find that both pebble bed configurations to have advantageous features that manifest at different stages of pebble crushing. However, all configurations benefit from achieving high initial packing fractions.

OEDGE modeling of outer wall erosion in NSTX and the effect of changes in neutral pressure

Energy Technology Data Exchange (ETDEWEB)

Nichols, J.H., E-mail: jnichols@pppl.gov; Jaworski, M.A.; Kaita, R.; Abrams, T.; Skinner, C.H.; Stotler, D.P.

2015-08-15

Gross erosion from the outer wall is expected to be a major source of impurities for high power fusion devices due to the low redeposition fraction. Scaling studies of sputtering from the all-carbon outer wall of NSTX are reported. It is found that wall erosion decreases with divertor plasma pressure in low/mid temperature regimes, due to increasing divertor neutral opacity. Wall erosion is found to consistently decrease with reduced recycling coefficient, with outer target recycling providing the largest contribution. Upper and lower bounds are calculated for the increase in wall erosion due to a low-field-side gas puff.

An in situ spatially resolved analytical technique to simultaneously probe gas phase reactions and temperature within the packed bed of a plug flow reactor.

Science.gov (United States)

Touitou, Jamal; Burch, Robbie; Hardacre, Christopher; McManus, Colin; Morgan, Kevin; Sá, Jacinto; Goguet, Alexandre

2013-05-21

This paper reports the detailed description and validation of a fully automated, computer controlled analytical method to spatially probe the gas composition and thermal characteristics in packed bed systems. As an exemplar, we have examined a heterogeneously catalysed gas phase reaction within the bed of a powdered oxide supported metal catalyst. The design of the gas sampling and the temperature recording systems are disclosed. A stationary capillary with holes drilled in its wall and a moveable reactor coupled with a mass spectrometer are used to enable sampling and analysis. This method has been designed to limit the invasiveness of the probe on the reactor by using the smallest combination of thermocouple and capillary which can be employed practically. An 80 μm (O.D.) thermocouple has been inserted in a 250 μm (O.D.) capillary. The thermocouple is aligned with the sampling holes to enable both the gas composition and temperature profiles to be simultaneously measured at equivalent spatially resolved positions. This analysis technique has been validated by studying CO oxidation over a 1% Pt/Al2O3 catalyst and the spatial resolution profiles of chemical species concentrations and temperature as a function of the axial position within the catalyst bed are reported.

On the second-order temperature jump coefficient of a dilute gas

Science.gov (United States)

Radtke, Gregg A.; Hadjiconstantinou, N. G.; Takata, S.; Aoki, K.

2012-09-01

We use LVDSMC simulations to calculate the second-order temperature jump coefficient for a dilute gas whose temperature is governed by the Poisson equation with a constant forcing term. Both the hard sphere gas and the BGK model of the Boltzmann equation are considered. Our results show that the temperature jump coefficient is different from the well known linear and steady case where the temperature is governed by the homogeneous heat conduction (Laplace) equation.

A global model for SF6 plasmas coupling reaction kinetics in the gas phase and on the surface of the reactor walls

International Nuclear Information System (INIS)

Kokkoris, George; Panagiotopoulos, Apostolos; Gogolides, Evangelos; Goodyear, Andy; Cooke, Mike

2009-01-01

Gas phase and reactor wall-surface kinetics are coupled in a global model for SF 6 plasmas. A complete set of gas phase and surface reactions is formulated. The rate coefficients of the electron impact reactions are based on pertinent cross section data from the literature, which are integrated over a Druyvesteyn electron energy distribution function. The rate coefficients of the surface reactions are adjustable parameters and are calculated by fitting the model to experimental data from an inductively coupled plasma reactor, i.e. F atom density and pressure change after the ignition of the discharge. The model predicts that SF 6 , F, F 2 and SF 4 are the dominant neutral species while SF 5 + and F - are the dominant ions. The fit sheds light on the interaction between the gas phase and the reactor walls. A loss mechanism for SF x radicals by deposition of a fluoro-sulfur film on the reactor walls is needed to predict the experimental data. It is found that there is a net production of SF 5 , F 2 and SF 6 , and a net consumption of F, SF 3 and SF 4 on the reactor walls. Surface reactions as well as reactions between neutral species in the gas phase are found to be important sources and sinks of the neutral species.

Exploitation of low-temperature energy sources from cogeneration gas engines

International Nuclear Information System (INIS)

Caf, A.; Urbancl, D.; Trop, P.; Goricanec, D.

2016-01-01

This paper describes an original and innovative technical solution for exploiting low-temperature energy sources from cogeneration gas reciprocating engines installed within district heating systems. This solution is suitable for those systems in which the heat is generated by the use of reciprocating engines powered by gaseous fuel for combined heat and power production. This new technical solution utilizes low-temperature energy sources from a reciprocating gas engine which is used for a combined production of heat and power. During the operation of the cogeneration system low-temperature heat is released, which can be raised to as much as 85 °C with the use of a high-temperature heat-pump, thus enabling a high-temperature regime for heating commercial buildings, district heating or in industrial processes. In order to demonstrate the efficiency of utilizing low-temperature heat sources in the cogeneration system, an economic calculation is included which proves the effectiveness and rationality of integrating high-temperature heat-pumps into new or existing systems for combined heat and power production with reciprocating gas engines. - Highlights: • The use of low-temperature waste heat from the CHP is described. • Total energy efficiency of the CHP can be increased to more than 103.3%. • Low-temperature heat is exploited with high-temperature heat pump. • High-temperature heat pump allows temperature rise to up to 85 °C. • Exploitation of low-temperature waste heat increases the economics of the CHP.

Computational scheme for transient temperature distribution in PWR vessel wall

International Nuclear Information System (INIS)

Dedovic, S.; Ristic, P.

1980-01-01

Computer code TEMPNES is a part of joint effort made in Gosa Industries in achieving the technique for structural analysis of heavy pressure vessels. Transient heat conduction problems analysis is based on finite element discretization of structures non-linear transient matrix formulation and time integration scheme as developed by Wilson (step-by-step procedure). Convection boundary conditions and the effect of heat generation due to radioactive radiation are both considered. The computation of transient temperature distributions in reactor vessel wall when the water temperature suddenly drops as a consequence of reactor cooling pump failure is presented. The vessel is treated as as axisymmetric body of revolution. The program has two finite time element options a) fixed predetermined increment and; b) an automatically optimized time increment for each step dependent on the rate of change of the nodal temperatures. (author)

Mixed convection of magnetohydrodynamic nanofluids inside microtubes at constant wall temperature

Energy Technology Data Exchange (ETDEWEB)

Moshizi, S.A. [Young Researchers and Elite Club, Neyshabur Branch, Islamic Azad University, Neyshabur (Iran, Islamic Republic of); Zamani, M. [Young Researchers and Elite Club, Gonabad Branch, Islamic Azad University, Gonabad (Iran, Islamic Republic of); Hosseini, S.J. [Department of Mechanical Engineering, School of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Malvandi, A., E-mail: amirmalvandi@aut.ac.ir [Department of Mechanical Engineering, Neyshabur Branch, Islamic Azad University, Neyshabur (Iran, Islamic Republic of)

2017-05-15

Laminar fully developed mixed convection of magnetohydrodynamic nanofluids inside microtubes at a constant wall temperature (CWT) under the effects of a variable directional magnetic field is investigated numerically. Nanoparticles are assumed to have slip velocities relative to the base fluid owing to thermophoretic diffusion (temperature gradient driven force) and Brownian diffusion (concentration gradient driven force). The no-slip boundary condition is avoided at the fluid-solid mixture to assess the non-equilibrium region at the fluid-solid interface. A scale analysis is performed to estimate the relative significance of the pertaining parameters that should be included in the governing equations. After the effects of pertinent parameters on the pressure loss and heat transfer enhancement were considered, the figure of merit (FoM) is employed to evaluate and optimize the thermal performance of heat exchange equipment. The results indicate the optimum thermal performance is obtained when the thermophoresis overwhelms the Brownian diffusion, which is for larger nanoparticles. This enhancement boosts when the buoyancy force increases. In addition, increasing the magnetic field strength and slippage at the fluid-solid interface enhances the thermal performance. - Highlights: • Thermally fully developed flow of nanofluid in circular microchannels at constant wall temperature. • Effect of nanoparticle migration on fluid flow and heat transfer characteristics. • Investigating the Figure of merit of thermal performance. • Performance of system grows when the thermophoresis overwhelms the Brownian diffusion.

Evaporation and condensation heat transfer with a noncondensable gas present

International Nuclear Information System (INIS)

Murase, M.; Kataoka, Y.; Fujii, T.

1993-01-01

To evaluate the system pressure of an external water wall type containment vessel, which is one of the passive systems for containment cooling, the evaporation and condensation behavior under a noncondensable gas presence has been experimentally examined. In the system, steam evaporated from the suppression pool surface into the wetwell, filled with noncondensable gas, and condensed on the containment vessel wall. The system pressure was the sum of the noncondensable gas pressure and saturated steam pressure in the wetwell. The wetwell temperature was, however, lower than the suppression pool temperature and depended on the thermal resistance on the suppression pool surface. The evaporation and condensation heat transfer coefficients in the presence of air as noncondensable gas were measured and expressed by functions of steam/air mass ratio. The evaporation heat transfer coefficients were one order higher than the condensation heat transfer coefficients because the local noncondensable gas pressure was much lower on the evaporating pool surface than on the condensing liquid surface. Using logal properties of the heat transfer surfaces, there was a similar trend between evaporation and condensation even with a noncondensable gas present. (orig.)

Design and development of gas turbine high temperature reactor 300

International Nuclear Information System (INIS)

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

2003-01-01

JAERI (Japan Atomic Energy Research Institute) has been designing a Japan's original gas turbine high temperature reactor, GTHTR300 (Gas Turbine High Temperature Reactor 300). The greatly simplified design based on salient features of the HTGR (High Temperature Gas-cooled reactor) with a closed helium gas turbine enables the GTHTR300 a high efficient and economically competitive reactor to be deployed in early 2010s. Also, the GTHTR300 fully taking advantage of various experiences accumulated in design, construction and operation of the HTTR (High Temperature Engineering Test Reactor) and fossil gas turbine systems reduces technological development concerning a reactor system and electric generation system. Original features of this system are core design with two-year refueling interval, conventional steel material usage for a reactor pressure vessel, innovative plant flow scheme and horizontally installed gas turbine unit. Due to these salient features, the capital cost of the GTHTR300 is less than a target cost of 200 thousands Yen/kWe, and the electric generation cost is close to a target cost of 4 Yen/kWh. This paper describes the original design features focusing on reactor core design, fuel design, in-core structure design and reactor pressure vessel design except PCU design. Also, R and D for developing the power conversion unit is briefly described. The present study is entrusted from the Ministry of Education, Culture, Sports, Science and Technology of Japan. (author)

High temperature gas cooled nuclear reactor

International Nuclear Information System (INIS)

Hosegood, S.B.; Lockett, G.E.

1975-01-01

For high-temperature gas cooled reactors it is considered advantageous to design the core so that the moderator blocks can be removed and replaced by some means of standpipes normally situated in the top of the reactor vessel. An arrangement is here described to facilitate these operations. The blocks have end faces shaped as irregular hexagons with three long sides of equal length and three short sides also of equal length, one short side being located between each pair of adjacent long sides, and the long sides being inclined towards one another at 60 0 . The block defines a number of coolant channels located parallel to its sides. Application of the arrangement to a high temperature gas-cooled reactor with refuelling standpipes is described. The standpipes are located in the top of the reactor vessel above the tops of the columns and are disposed coaxially above the hexagonal channels, with diameters that allow the passage of the blocks. (U.K.)

Fuel hydrogen retention of tungsten and the reduction by inert gas glow discharges

Energy Technology Data Exchange (ETDEWEB)

Hino, T., E-mail: tomhino@qe.eng.hokudai.ac.jp [Laboratory of Plasma Physics and Engineering, Hokkaido University, Sapporo 060-8628 (Japan); Yamauchi, Y.; Kimura, Y. [Laboratory of Plasma Physics and Engineering, Hokkaido University, Sapporo 060-8628 (Japan); Nishimura, K. [National Institute for Fusion Science, Toki-shi, Gifu-ken 509-5292 (Japan); Ueda, Y. [Graduate School of Engineering, Osaka University, Suita-shi 565-0872 (Japan)

2012-08-15

Highlights: Black-Right-Pointing-Pointer The performances of inert gas glow discharges for reduction of fuel hydrogen retention in tungsten were systematically investigated. Black-Right-Pointing-Pointer For the tungsten with rough surface structure, the reduction of fuel hydrogen retention by inert gas discharges is quite small. Black-Right-Pointing-Pointer The deuterium glow discharge is quite useful to reduce the tritium retention in plasma facing walls in fusion reactor. Black-Right-Pointing-Pointer The wall baking with temperature higher than 700-800 K is also useful to reduce the tritium retention in plasma facing walls. - Abstract: Polycrystalline tungsten was exposed to deuterium glow discharge followed by He, Ne or Ar glow discharge. The amount of retained deuterium in the tungsten was measured using residual gas analysis. The amount of desorbed deuterium during the inert gas glow discharge was also measured. The amount of retained deuterium was 2-3 times larger compared with a case of stainless steel. The ratios of desorbed amount of deuterium by He, Ne and Ar glow discharges were 4.6, 3.1 and 2.9%, respectively. These values were one order of magnitude smaller compared with the case of stainless steel. The inert gas glow discharge is not suitable to reduce the fuel hydrogen retention for tungsten walls. However, the wall baking with a temperature higher than 700 K is suitable to reduce the fuel hydrogen retention. It is also shown that the use of deuterium glow discharge is effective to reduce the in-vessel tritium inventory in fusion reactors through the hydrogen isotope exchange.

Analysis and improvement of gas turbine blade temperature measurement error

International Nuclear Information System (INIS)

Gao, Shan; Wang, Lixin; Feng, Chi; Daniel, Ketui

2015-01-01

Gas turbine blade components are easily damaged; they also operate in harsh high-temperature, high-pressure environments over extended durations. Therefore, ensuring that the blade temperature remains within the design limits is very important. In this study, measurement errors in turbine blade temperatures were analyzed, taking into account detector lens contamination, the reflection of environmental energy from the target surface, the effects of the combustion gas, and the emissivity of the blade surface. In this paper, each of the above sources of measurement error is discussed, and an iterative computing method for calculating blade temperature is proposed. (paper)

Analysis and improvement of gas turbine blade temperature measurement error

Science.gov (United States)

Gao, Shan; Wang, Lixin; Feng, Chi; Daniel, Ketui

2015-10-01

Gas turbine blade components are easily damaged; they also operate in harsh high-temperature, high-pressure environments over extended durations. Therefore, ensuring that the blade temperature remains within the design limits is very important. In this study, measurement errors in turbine blade temperatures were analyzed, taking into account detector lens contamination, the reflection of environmental energy from the target surface, the effects of the combustion gas, and the emissivity of the blade surface. In this paper, each of the above sources of measurement error is discussed, and an iterative computing method for calculating blade temperature is proposed.

Mixing enhancement of low-Reynolds electro-osmotic flows in microchannels with temperature-patterned walls.

Science.gov (United States)

Alizadeh, A; Zhang, L; Wang, M

2014-10-01

Mixing becomes challenging in microchannels because of the low Reynolds number. This study aims to present a mixing enhancement method for electro-osmotic flows in microchannels using vortices caused by temperature-patterned walls. Since the fluid is non-isothermal, the conventional form of Nernst-Planck equation is modified by adding a new migration term which is dependent on both temperature and internal electric potential gradient. This term results in the so-called thermo-electrochemical migration phenomenon. The coupled Navier-Stokes, Poisson, modified Nernst-Planck, energy and advection-diffusion equations are iteratively solved by multiple lattice Boltzmann methods to obtain the velocity, internal electric potential, ion distribution, temperature and species concentration fields, respectively. To enhance the mixing, three schemes of temperature-patterned walls have been considered with symmetrical or asymmetrical arrangements of blocks with surface charge and temperature. Modeling results show that the asymmetric arrangement scheme is the most efficient scheme and enhances the mixing of species by 39% when the Reynolds number is on the order of 10(-3). Current results may help improve the design of micro-mixers at low Reynolds number. Copyright © 2014 Elsevier Inc. All rights reserved.

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

Science.gov (United States)

Bahrami, Parviz A.

2012-01-01

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

Multi-spectral temperature measurement method for gas turbine blade

Science.gov (United States)

Gao, Shan; Feng, Chi; Wang, Lixin; Li, Dong

2016-02-01

One of the basic methods to improve both the thermal efficiency and power output of a gas turbine is to increase the firing temperature. However, gas turbine blades are easily damaged in harsh high-temperature and high-pressure environments. Therefore, ensuring that the blade temperature remains within the design limits is very important. There are unsolved problems in blade temperature measurement, relating to the emissivity of the blade surface, influences of the combustion gases, and reflections of radiant energy from the surroundings. In this study, the emissivity of blade surfaces has been measured, with errors reduced by a fitting method, influences of the combustion gases have been calculated for different operational conditions, and a reflection model has been built. An iterative computing method is proposed for calculating blade temperatures, and the experimental results show that this method has high precision.

Research and Development of Heavy Wall DNV485FDU Pipeline Plate for 3500M Deep Water Pipe Applications at Shougang

Science.gov (United States)

Ding, Wenhua; Li, Shaopo; Li, Jiading; Li, Qun; Chen, Tieqiang; Zhang, Hai

In recent years, there has been development of several significant pipeline projects for the transmission of oil and gas from deep water environments. The production of gas transmission pipelines for application demands heavy wall, high strength, good lower temperature toughness and good weldability. To overcome the difficulty of producing consistent mechanical property in heavy wall pipe Shougang Steel Research in cooperation with the Shougang Steel Qinhuangdao China (Shouqin) 4.3m heavy wide plate mill research was conducted.

Moderate temperature gas purification system: application to high calorific coal derived fuel

Energy Technology Data Exchange (ETDEWEB)

M. Kobayashi; H. Shirai; M. Nunokawa [Central Research Institute of Electric Power Industry (CRIEPI), Kanagawa (Japan)

2005-07-01

Simultaneous removal of dust, alkaline and alkaline-earth metals, halides and sulfur compounds is required to enlarge application of coal-derived gas to the high temperature fuel cells and the fuel synthesis through chemical processing. Because high calorific fuel gas, such as oxygen-blown coal gas, has high carbon monoxide content, high temperature gas purification system is always subjected to the carbon deposition and slippage of contaminant of high vapor pressure. It was suggested that moderate temperature operation of the gas purification system is applied to avoid the harmful disproportionation reaction and efficient removal of the various contaminants. To establish the moderate temperature gas purification system, the chemical-removal processes where the reaction rate is predominant to the performance of contaminant removal should be evaluated. Performance of the removal processes for halides and sulfur compounds were experimentally evaluated. The halide removal process with sodium based sorbent had potential good performance at around 300{sup o}C. The sulfur removal process was also applicable to the temperature range, although the improvement of the sulfidation reaction rate is considered to be essential. 11 refs., 8 figs., 1 tab.

Rotational temperature determinations in molecular gas lasers

International Nuclear Information System (INIS)

Weaver, L.A.; Taylor, L.H.; Denes, L.J.

1975-01-01

The small-signal gain expressions for vibrational-rotational transitions are examined in detail to determine possible methods of extracting the rotational temperature from experimental gain measurements in molecular gas lasers. Approximate values of T/subr/ can be deduced from the rotational quantum numbers for which the P- and R-branch gains are maximum. Quite accurate values of T/subr/ and the population inversion density (n/subv//sub prime/-n/subv//sub double-prime/) can be determined by fitting data to suitably linearized gain relationships, or by performing least-squares fits of the P- and R-branch experimental data to the full gain expressions. Experimental gain measurements for 15 P-branch and 12 R-branch transitions in the 10.4-μm CO 2 band have been performed for pulsed uv-preionized laser discharges in CO 2 : N 2 : He=1 : 2 : 3 mixtures at 600 Torr. These data are subjected to the several gain analyses described herein, yielding a rotational temperature of 401plus-or-minus10 degreeK and an inversion density of (3.77plus-or-minus0.07) times10 17 cm -3 for conditions of maximum gain. These techniques provide accurate values of the gas temperature in molecular gas lasers with excellent temporal and spatial resolution, and should be useful in extending the conversion efficiency and arcing limits of high-energy electrically exc []ted lasers

Design and performance tests of gas circulation heating of JT-60U vacuum vessel

International Nuclear Information System (INIS)

Yotsuga, M.; Masuzaki, T.; Sago, H.; Nishikane, M.; Uchikawa, T.; Iritani, Y.; Murakami, T.; Horiike, H.; Neyatani, Y.; Ninomiya, H.; Matsukawa, M.; Ando, T.; Miyachi, I.

1992-01-01

This paper reports that in the final stage of construction of the upgraded JT-60 device (JT-60U), baking tests of the vacuum vessel was performed. The vessel torus was heated-up to 300 degrees C by means of the nitrogen gas circulation system and electric heaters mounted on the outboard solid wall of the vessel. The design of the gas flow channels inside the double-wall structure of the vessel was done based on flow model tests, fluid analysis, and flow network analysis. The results of the baking tests were satisfactory. In maintaining 300 degrees C bake-out temperature, required heating power of the gas circulation system and outboard heaters was 520kW and 50kW, respectively. The temperature distribution over the vessel wall was within 300 ± 30 degrees C. It was also shown or suggested that heat-up and cool-down time is about 30 hours. The baking tests data have been reflected on operations for plasma experiments

Study on flow instability for feasibility of a thin liquid film first wall

Energy Technology Data Exchange (ETDEWEB)

Okino, Fumito, E-mail: fumito.okino@iae.kyoto-u.ac.jp [Kyoto University Graduate School of Energy Science, Gokasho Uji, Kyoto (Japan); Kasada, Ryuta; Konishi, Satoshi [Kyoto University Institute of Advanced Energy, Gokasho Uji, Kyoto (Japan)

2014-10-15

Highlights: • We propose a probability of an instability wave growth on a liquid metal first wall. • Evaporated gas by the high energy flux is predicted to agitate this instability wave. • Liquid Pb-17Li with a velocity 10 m/s, the ambient gas must be below 6.2 × 10{sup 3} Pa. • This pressure corresponds to 1600 K and it is attainable under a fusion energy flux. • This probability is not yet verified so the full verifications are to be performed. - Abstract: This study proposes a probability of the evaporated gas that agitates a growing instability wave in a thin liquid film first wall. The liquid first wall was considered to be in vacuum and the effect of the ambient gas was neglected but the evaporated gas by the high energy fluxes is a probable cause of unstable wave agitation. The criterion is approximately expressed by the density ratio (Q{sub 2}) and the Weber number (We) as Q{sub 2} × We{sup 0.5} ≈ 5 × 10{sup −4}. Performed indirect experimental supported this criterion. For a case study of liquid Pb-17Li film with a velocity of 10 m/s, the evaporated gas pressure must be below 6.2 × 10{sup 3} Pa to maintain stable conditions. By recent study, this pressure is generated at 1600 K temperature and it is believed to be attainable by the energy fluxes on the first wall. This result is so far not confirmed so the full verification by experimental is to be performed.

Gas-surface interactions using accommodation coefficients for a dilute and a dense gas in a micro/nano-channel : heat flux predictions using combined molecular dynamics and Monte Carlo techniques

NARCIS (Netherlands)

Gaastra - Nedea, S.V.; Steenhoven, van A.A.; Markvoort, A.J.; Spijker, P.; Giordano, D.

2014-01-01

The influence of gas-surface interactions of a dilute gas confined between two parallel walls on the heat flux predictions is investigated using a combined Monte Carlo (MC) and molecular dynamics (MD) approach. The accommodation coefficients are computed from the temperature of incident and

Thermal performance of a micro-combustor for micro-gas turbine system

International Nuclear Information System (INIS)

Cao, H.L.; Xu, J.L.

2007-01-01

Premixed combustion of hydrogen gas and air was performed in a stainless steel based micro-annular combustor for a micro-gas turbine system. Micro-scale combustion has proved to be stable in the micro-combustor with a gap of 2 mm. The operating range of the micro-combustor was measured, and the maximum excess air ratio is up to 4.5. The distribution of the outer wall temperature and the temperature of exhaust gas of the micro-combustor with excess air ratio were obtained, and the wall temperature of the micro-combustor reaches its maximum value at the excess air ratio of 0.9 instead of 1 (stoichiometric ratio). The heat loss of the micro-combustor to the environment was calculated and even exceeds 70% of the total thermal power computed from the consumed hydrogen mass flow rate. Moreover, radiant heat transfer covers a large fraction of the total heat loss. Measures used to reduce the heat loss were proposed to improve the thermal performance of the micro-combustor. The optimal operating status of the micro-combustor and micro-gas turbine is analyzed and proposed by analyzing the relationship of the temperature of the exhaust gas of the micro-combustor with thermal power and excess air ratio. The investigation of the thermal performance of the micro-combustor is helpful to design an improved micro-combustor

A photovoltaic self-powered gas sensor based on a single-walled carbon nanotube/Si heterojunction.

Science.gov (United States)

Liu, L; Li, G H; Wang, Y; Wang, Y Y; Li, T; Zhang, T; Qin, S J

2017-12-07

We present a novel photovoltaic self-powered gas sensor based on a p-type single-walled carbon nanotube (SWNT) and n-type silicon (n-Si) heterojunction. The energy from visible light suffices to drive the device owing to a built-in electric field (BEF) induced by the differences between the Fermi levels of SWNTs and n-Si.

Breakdown voltage reduction by field emission in multi-walled carbon nanotubes based ionization gas sensor

Energy Technology Data Exchange (ETDEWEB)

Saheed, M. Shuaib M.; Muti Mohamed, Norani; Arif Burhanudin, Zainal, E-mail: zainabh@petronas.com.my [Centre of Innovative Nanostructures and Nanodevices, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia)

2014-03-24

Ionization gas sensors using vertically aligned multi-wall carbon nanotubes (MWCNT) are demonstrated. The sharp tips of the nanotubes generate large non-uniform electric fields at relatively low applied voltage. The enhancement of the electric field results in field emission of electrons that dominates the breakdown mechanism in gas sensor with gap spacing below 14 μm. More than 90% reduction in breakdown voltage is observed for sensors with MWCNT and 7 μm gap spacing. Transition of breakdown mechanism, dominated by avalanche electrons to field emission electrons, as decreasing gap spacing is also observed and discussed.

Evaporation and condensation heat transfer in a suppression chamber of the water wall type passive containment cooling system

International Nuclear Information System (INIS)

Fujii, Tadashi; Kataoka, Yoshiyuki; Murase, Michio

1996-01-01

To evaluate the system pressure response of a water wall type containment cooling system, which is one of the passive safety systems, the evaporation and condensation behaviors in a suppression chamber have been experimentally examined. In the system, the suppression pool water evaporates from the pool surface, passing into the wetwell due to pool temperature rise, while steam in the wetwell condenses on the steel containment vessel wall due to the heat release through the wall. The wetwell is a gas phase region in the suppression chamber and its pressure, which is expressed as the sum of the noncondensable gas pressure and saturated steam pressure, is strongly affected by the evaporation heat transfer from the suppression pool surface and condensation heat transfer on the containment vessel wall. Based on the measured temperature profiles near the heat transfer surface and the wetwell pressure using two apparatuses, evaporation and condensation heat transfer coefficients were evaluated. The following results were obtained. (1) Both heat transfer coefficients increased as the ratio of the steam partial pressure to the total pressure increased. (2) Comparison of the results from two types of test apparatuses confirmed that the size of the heat transfer surface did not affect the heat transfer characteristics within these tests. (3) The heat transfer coefficients were expressed by the ratio of the steam to noncondensable gas logarithmic mean concentration, which considered the steam and gas concentration gradient from the heat transfer surface to the wetwell bulk. (author)

Thermodynamics of a classical ideal gas at arbitrary temperatures

OpenAIRE

Pal, Palash B.

2002-01-01

We propose a fundamental relation for a classical ideal gas that is valid at all temperatures with remarkable accuracy. All thermodynamical properties of classical ideal gases can be deduced from this relation at arbitrary temperature.

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

Atomic and molecular hydrogen gas temperatures in a low-pressure helicon plasma

Science.gov (United States)

Samuell, Cameron M.; Corr, Cormac S.

2015-08-01

Neutral gas temperatures in hydrogen plasmas are important for experimental and modelling efforts in fusion technology, plasma processing, and surface modification applications. To provide values relevant to these application areas, neutral gas temperatures were measured in a low pressure (radiofrequency helicon discharge using spectroscopic techniques. The atomic and molecular species were not found to be in thermal equilibrium with the atomic temperature being mostly larger then the molecular temperature. In low power operation (measurements near a graphite target demonstrated localised cooling near the sample surface. The temporal evolution of the molecular gas temperature during a high power 1.1 ms plasma pulse was also investigated and found to vary considerably as a function of pressure.

Gas Temperature and Radiative Heat Transfer in Oxy-fuel Flames

DEFF Research Database (Denmark)

Bäckström, Daniel; Johansson, Robert; Andersson, Klas

This work presents measurements of the gas temperature, including fluctuations, and its influence on the radiative heat transfer in oxy-fuel flames. The measurements were carried out in the Chalmers 100 kW oxy-fuel test unit. The in-furnace gas temperature was measured by a suction pyrometer...... on the radiative heat transfer shows no effect of turbulence-radiation interaction. However, by comparing with temperature fluctuations in other flames it can be seen that the fluctuations measured here are relatively small. Further research is needed to clarify to which extent the applied methods can account...

Experimental Study of gas-liquid two-phase flow affected by wall surface wettability

International Nuclear Information System (INIS)

Takamasa, T.; Hazuku, T.; Hibiki, T.

2008-01-01

To evaluate the effect of wall surface wettability on the characteristics of upward gas-liquid two-phase flow in a vertical pipe, an experimental study was performed using three test pipes: an acrylic pipe, a hydrophilic pipe and a hydrophobic pipe. Basic flow characteristics such as flow patterns, pressure drop and void fraction were measured in these three pipes. In the hydrophilic pipe, a slug to churn flow transition boundary was shifted to a higher gas velocity at a given liquid velocity, whereas a churn to annular flow transition boundary was shifted to a lower gas velocity at a given liquid velocity. In the hydrophobic pipe, an inverted-churn flow regime was observed in the region where the churn flow regime was observed in the acrylic pipe, while a droplet flow regime was observed in the region where an annular flow regime was observed in the acrylic pipe. At a high gas flow rate, the mean void fraction in the hydrophobic pipe was higher than in the acrylic pipe. The effect of surface wettability on frictional pressure loss was confirmed to be insignificant under the present experimental conditions

Development history of the gas turbine modular high temperature reactor

International Nuclear Information System (INIS)

Brey, H.L.

2001-01-01

The development of the high temperature gas cooled reactor (HTGR) as an environmentally agreeable and efficient power source to support the generation of electricity and achieve a broad range of high temperature industrial applications has been an evolutionary process spanning over four decades. This process has included ongoing major development in both the HTGR as a nuclear energy source and associated power conversion systems from the steam cycle to the gas turbine. This paper follows the development process progressively through individual plant designs from early research of the 1950s to the present focus on the gas turbine modular HTGR. (author)

Fast temperature programming in gas chromatography using resistive heating

NARCIS (Netherlands)

Dallüge, J.; Ou-Aissa, R.; Vreuls, J.J.; Brinkman, U.A.T.; Veraart, J.R.

1999-01-01

The features of a resistive-heated capillary column for fast temperature-programmed gas chromatography (GC) have been evaluated. Experiments were carried out using a commercial available EZ Flash GC, an assembly which can be used to upgrade existing gas chromatographs. The capillary column is placed

Application of partially diabatic divided wall column to floating liquefied natural gas plant

International Nuclear Information System (INIS)

Kim, Young Han

2014-01-01

The offshore operation of chemical plant requires the compactness of process equipments due to its harsh environment. A DWC (divided wall column), a compact ternary separator, is a good candidate for distillation process in the offshore operation. In this study the DWC is applied to the offshore FLNG (floating liquefied natural gas) plant, but high utility cost is required in the application because of the large difference of boiling points among feed components. A partially diabatic DWC is proposed for the reduction of the operating cost here, and its design procedure is presented along with performance and economic evaluations and the examination of thermodynamic efficiency as well. The heating duty of the proposed DWC including tray heat transfer is 35% less than that of the conventional system, and the cooling duty is 18% less. The evaluation indicates that some 16% less utility cost is used in the DWC compared with the conventional system, though 7% more investment is required. The exergy loss is reduced by 12%, and the thermodynamic efficiency is improved by 3.3 percentage point over the conventional system. - Highlights: • Diabatic divided wall column for FLNG (floating liquefied natural gas) plant. • Compact column for offshore operation. • 35% less heating duty required. • 16% lower utility necessary. • Exergy loss reduced by 12%

Bloch walls and the non-ideal bose gas spectrum

International Nuclear Information System (INIS)

Vitiello, S.A.S.

1986-05-01

The quasi-particle spectrum of non-ideal Bose gas with domain walls in the condensate is investigated. The existence of such a system is determined from solutions of Gross-Pitaevskii equation which represent many-soliton systems. The walls which make the condensate non-uniform are responsible for density and velocity fields ρ(x) and υ(x) repectively. In the laboratory, the Bogoliubov spectrum, supposed to be true for an uniform condensate at rest, is changed due to the velocity field to which the quasi-particles are submited. The spectrum in the laboratory frame is obtained by considering the Galileu invariance principle and the interaction energy between the quasi-particle and its medium. The importance in considering the last two facts is illustrated by the analyse of a constant density condensate which moves uniformly in the laboratory. The many-soliton spectrum configuration and structure function are studied by the Monte Carlo method. In an approximation that assumes the quasi-particle to be point like, the condensate can be treated as locally uniform. For each event the position x of a quasi-particle and its momentum in a frame with velocity υ(x) are determined. Thus, by a convenient Galileu transformation the energy spectrum in the laboratory an be obtained. The results show a phonon spectrum which splits in two branches in the high momenta region. In this region the lower energy branch exibiths a point of minimum. Analogies with the He II are explored. (author) [pt

Simulation of temperature-pressure profiles and wax deposition in gas-lift wells

Directory of Open Access Journals (Sweden)

Sevic Snezana

2017-01-01

Full Text Available Gas-lift is an artificial lift method in which gas is injected down the tubing- -casing annulus and enters the production tubing through the gas-lift valves to reduce the hydrostatic pressure of the formation fluid column. The gas changes pressure, temperature and fluid composition profiles throughout the production tubing string. Temperature and pressure drop along with the fluid composition changes throughout the tubing string can lead to wax, asphaltenes and inorganic salts deposition, increased emulsion stability and hydrate formation. This paper presents a new model that can sucesfully simulate temperature and pressure profiles and fluid composition changes in oil well that operates by means of gas-lift. This new model includes a pipe-in-pipe segment (production tubing inside production casing, countercurrent flow of gas-lift gas and producing fluid, heat exchange between gas-lift gas and the surrounding ambient – ground; and gas-lift gas with the fluid in the tubing. The model enables a better understanding of the multiphase fluid flow up the production tubing. Model was used to get insight into severity and locations of wax deposition. The obtained information on wax deposition can be used to plan the frequency and depth of wax removing operations. Model was developed using Aspen HYSYS software.

Extended Macroscopic Study of Dilute Gas Flow within a Microcavity

Directory of Open Access Journals (Sweden)

Mohamed Hssikou

2016-01-01

Full Text Available The behaviour of monatomic and dilute gas is studied in the slip and early transition regimes using the extended macroscopic theory. The gas is confined within a two-dimensional microcavity where the longitudinal sides are in the opposite motion with constant velocity ±Uw. The microcavity walls are kept at the uniform and reference temperature T0. Thus, the gas flow is transported only by the shear stress induced by the motion of upper and lower walls. From the macroscopic point of view, the regularized 13-moment equations of Grad, R13, are solved numerically. The macroscopic gas proprieties are studied for different values of the so-called Knudsen number (Kn, which gives the gas-rarefaction degree. The results are compared with those obtained using the classical continuum theory of Navier-Stokes and Fourier (NSF.

Thermal regime of a continental permafrost associated gas hydrate occurrence a continuous temperature profile record after drilling

Science.gov (United States)

Henninges, J.; Huenges, E.; Mallik Working Group

2003-04-01

Both the size and the distribution of natural methane hydrate occurrences, as well as the release of gaseous methane through the dissociation of methane hydrate, are affected by the subsurface pressure and temperature conditions. During a field experiment, which was carried out in the Mackenzie Delta, NWT, Canada, within the framework of the Mallik 2002 Production Research Well Program*, the variation of temperature within three 40 m spaced, 1200 m deep wells was measured deploying the Distributed Temperature Sensing (DTS) technology. An innovative experimental design for the monitoring of spatial and temporal variations of temperature along boreholes was developed and successfully applied under extreme arctic conditions. A special feature is the placement of the fibre-optic sensor cable inside the cement annulus between the casing and the wall of the borehole. Temperature profiles were recorded with a sampling interval of 0.25 m and 5 min, and temperatures can be determined with a resolution of 0.3 °C. The observed variation of temperature over time shows the decay of the thermal disturbances caused by the drilling and construction of the wells. An excellent indicator for the location of the base of the ice-bonded permafrost layer, which stands out as a result of the latent heat of the frozen pore fluid, is a sharp rise in temperature at 604 m depth during the period of equilibration. A similar effect can be detected in the depth interval between 1105 m and 1110 m, which is interpreted as an indicator for the depth to the base of the methane hydrate stability zone. Nine months after the completion of the wells the measured borehole temperatures are close to equilibrium. The mean temperature gradient rises from 9.4 K/km inside the permafrost to 25.4 K/km in the ice-free sediment layers underneath. The zone of the gas hydrate occurrences between 900 m and 1100 m shows distinct variations of the geothermal gradient, which locally rises up to 40 K/km. At the lower

Recoverying device for sodium vapor in inert gas

Energy Technology Data Exchange (ETDEWEB)

Nakagawa, Tamotsu; Nagashima, Ikuo

1992-11-06

A multi-pipe type heat exchanger for cooling an inert gas and a mist trap connected to the inert gas exit of the heat exchanger are disposed. A mist filter having bottomed pipes made of an inert gas-permeable sintered metal is disposed in the mist trap, and an inert gas discharge port is disposed at the upper side wall. With such a constitution, a high temperature inert gas containing sodium vapors can be cooled efficiently by the multi-pipe type heat exchanger capable of easy temperature control, thereby converting sodium vapors into mists, and the inert gas containing sodium mists can be flown into the mist trap. Sodium mists are collected by the mist filter and sodium mists flown down are discharged from the discharge port. With such procedures, a great amount of the inert gas containing sodium vapors can be processed continuously. (T.M.).

Titanium dioxide thin films for high temperature gas sensors

Energy Technology Data Exchange (ETDEWEB)

Seeley, Zachary Mark; Bandyopadhyay, Amit; Bose, Susmita, E-mail: sbose@wsu.ed

2010-10-29

Titanium dioxide (TiO{sub 2}) thin film gas sensors were fabricated via the sol-gel method from a starting solution of titanium isopropoxide dissolved in methoxyethanol. Spin coating was used to deposit the sol on electroded aluminum oxide (Al{sub 2}O{sub 3}) substrates forming a film 1 {mu}m thick. The influence of crystallization temperature and operating temperature on crystalline phase, grain size, electronic conduction activation energy, and gas sensing response toward carbon monoxide (CO) and methane (CH{sub 4}) was studied. Pure anatase phase was found with crystallization temperatures up to 800 {sup o}C, however, rutile began to form by 900 {sup o}C. Grain size increased with increasing calcination temperature. Activation energy was dependent on crystallite size and phase. Sensing response toward CO and CH{sub 4} was dependent on both calcination and operating temperatures. Films crystallized at 650 {sup o}C and operated at 450 {sup o}C showed the best selectivity toward CO.

Simulation for temperature changing investigation at RSG-GAS cooling system

International Nuclear Information System (INIS)

Utaja

2002-01-01

The RSG-GAS cooling system considers of primary and secondary system, is used for heat rejection from reactor core to the atmosphere. For temperature changing investigation cause by atmospherics condition changing or coolant flow rate changing, is more safe done by simulation. This paper describes the simulation for determine the RSG-GAS coolant temperature changing base on heat exchange and cooling tower characteristic. The simulation is done by computer programme running under WINDOWS 95 or higher. The temperature changing is based on heat transfer process on heat exchanger and cooling tower. The simulation will show the water tank temperature changing caused by the temperature and humidity of the atmosphere or by coolant flow rate changing. For example the humidity changing from 60% to 80% atmospherics temperature 30 oC and 32400 k Watt power will change the tank temperature from 37,97 oC to 40,03 oC

Temperature profile and producer gas composition of high temperature air gasification of oil palm fronds

International Nuclear Information System (INIS)

Guangul, F M; Sulaiman, S A; Ramli, A

2013-01-01

Environmental pollution and scarcity of reliable energy source are the current pressing global problems which need a sustainable solution. Conversion of biomass to a producer gas through gasification process is one option to alleviate the aforementioned problems. In the current research the temperature profile and composition of the producer gas obtained from the gasification of oil palm fronds by using high temperature air were investigated and compared with unheated air. By preheating the gasifying air at 500°C the process temperature were improved and as a result the concentration of combustible gases and performance of the process were improved. The volumetric percentage of CO, CH4 and H2 were improved from 22.49, 1.98, and 9.67% to 24.98, to 2.48% and 13.58%, respectively. In addition, HHV, carbon conversion efficiency and cold gas efficiency were improver from 4.88 MJ/Nm3, 83.8% and 56.1% to 5.90 MJ/Nm3, 87.3% and 62.4%, respectively.

Onsager's pancake approximation for the fluid dynamics of a gas centrifuge

International Nuclear Information System (INIS)

Wood, H.G. III; Morton, J.B.

1980-01-01

A previously unpublished theory for describing the internal flow in a gas centrifuge is presented. The theory is based on boundary layer type arguments on the side walls of the centrifuge with the additional approximation of neglecting radial diffusion of radial momentum. The effects of the top and bottom end caps are incorporated through Ekman layer solutions. The results are presented in a form amenable to numerical calculations. Some sample calculations are presented for the special case of a centrifuge with a linear temperature profile on the wall and the top and bottom of the centrifuge at the same temperature as the corresponding end of the side wall

Onsager's pancake approximation for the fluid dynamics of a gas centrifuge

International Nuclear Information System (INIS)

Wood, H.G.

1980-01-01

A previously unpublished theory for describing the internal flow in a gas centrifuge is presented. The theory is based on boundary-layer-type arguments on the side walls of the centrifuge with the additional approximation of neglecting radial diffusion of radial momentum. The effects of the top and bottom end caps are incorporated through Ekman-layer solutions. The results are presented in a form amenable to numerical calculations. Some sample calculations are presented for the special case of a centrifuge with a linear temperature profile on the wall and the top and bottom of the centrifuge at the same temperature as the corresponding end of the side wall. (author)

Plant cell wall sugars: sweeteners for a bio-based economy.

Science.gov (United States)

Van de Wouwer, Dorien; Boerjan, Wout; Vanholme, Bartel

2018-02-12

Global warming and the consequent climate change is one of the major environmental challenges we are facing today. The driving force behind the rise in temperature is our fossil-based economy, which releases massive amounts of the greenhouse gas carbon dioxide into the atmosphere. In order to reduce greenhouse gas emission, we need to scale down our dependency on fossil resources, implying that we need other sources for energy and chemicals to feed our economy. Here, plants have an important role to play; by means of photosynthesis, plants capture solar energy to split water and fix carbon derived from atmospheric carbon dioxide. A significant fraction of the fixed carbon ends up as polysaccharides in the plant cell wall. Fermentable sugars derived from cell wall polysaccharides form an ideal carbon source for the production of bio-platform molecules. However, a major limiting factor in the use of plant biomass as feedstock for the bio-based economy is the complexity of the plant cell wall and its recalcitrance towards deconstruction. To facilitate the release of fermentable sugars during downstream biomass processing, the composition and structure of the cell wall can be engineered. Different strategies to reduce cell wall recalcitrance will be described in this review. The ultimate goal is to obtain a tailor-made biomass, derived from plants with a cell wall optimized for particular industrial or agricultural applications, without affecting plant growth and development. This article is protected by copyright. All rights reserved.

The effect of different temperature profiles upon the length and crystallinity of vertically-aligned multi-walled carbon nanotubes.

Science.gov (United States)

Yun, Jongju; Lee, Cheesung; Zheng, Qing; Baik, Seunghyun

2012-08-01

We synthesized vertically-aligned multi-walled carbon nanotubes with an inner diameter of 1.6-7.5 nm and stack height of 80-28600 microm by chemical vapor deposition. The effects of synthesis conditions such as substrate position in the tube furnace, maximum temperature, temperature increasing rate and synthesis duration on the structure of nanotubes were investigated. It was found that slightly faster temperature increase rate resulted in significantly longer length, larger diameter and more defects of nanotubes. Structural parameters such as inner, outer diameters, wall thickness and defects were investigated using transmission electron microscopy and Raman spectroscopy.

Detailed disc assembly temperature prediction: comparison between CFD and simplified engineering methods

CSIR Research Space (South Africa)

Snedden, Glen C

2003-09-01

Full Text Available Institute of Aeronautics and Astronautics Inc. All rights reserved. DETAILED DISC ASSEMBLY TEMPERATURE PREDICTION: COMPARISON BETWEEN CFD AND SIMPLIFIED ENGINEERING METHODS ISABE-2005-1130 Glen Snedden, Thomas Roos and Kavendra Naidoo CSIR, Defencetek... transfer and conduction code (Gaugler, 1978) Taw Adiabatic Wall Temperature y+ Near wall Reynolds number Introduction In order to calculate life degradation of gas turbine disc assemblies, it is necessary to model the transient thermal and mechanical...

Bayesian inferences of the thermal properties of a wall using temperature and heat flux measurements

KAUST Repository

Iglesias, Marco

2017-09-20

The assessment of the thermal properties of walls is essential for accurate building energy simulations that are needed to make effective energy-saving policies. These properties are usually investigated through in situ measurements of temperature and heat flux over extended time periods. The one-dimensional heat equation with unknown Dirichlet boundary conditions is used to model the heat transfer process through the wall. In Ruggeri et al. (2017), it was assessed the uncertainty about the thermal diffusivity parameter using different synthetic data sets. In this work, we adapt this methodology to an experimental study conducted in an environmental chamber, with measurements recorded every minute from temperature probes and heat flux sensors placed on both sides of a solid brick wall over a five-day period. The observed time series are locally averaged, according to a smoothing procedure determined by the solution of a criterion function optimization problem, to fit the required set of noise model assumptions. Therefore, after preprocessing, we can reasonably assume that the temperature and the heat flux measurements have stationary Gaussian noise and we can avoid working with full covariance matrices. The results show that our technique reduces the bias error of the estimated parameters when compared to other approaches. Finally, we compute the information gain under two experimental setups to recommend how the user can efficiently determine the duration of the measurement campaign and the range of the external temperature oscillation.

Overview of the JET results with the ITER-like wall

DEFF Research Database (Denmark)

Romanelli, F.; Madsen, Jens; Naulin, Volker

2013-01-01

Following the completion in May 2011 of the shutdown for the installation of the beryllium wall and the tungsten divertor, the first set of JET campaigns have addressed the investigation of the retention properties and the development of operational scenarios with the new plasma-facing materials...... that the fuel retention rate with the new wall is substantially reduced with respect to the C wall. The re-establishment of the baseline H-mode and hybrid scenarios compatible with the new wall has required an optimization of the control of metallic impurity sources and heat loads. Stable type-I ELMy H......-mode regimes with H98,y2 close to 1 and βN ∼ 1.6 have been achieved using gas injection. ELM frequency is a key factor for the control of the metallic impurity accumulation. Pedestal temperatures tend to be lower with the new wall, leading to reduced confinement, but nitrogen seeding restores high pedestal...

Forced convection heat transfer in rectangular ducts - general case of wall resistances and peripheral conduction for ventilation cooling of nuclear waste repositories

International Nuclear Information System (INIS)

Lyczkowski, R.W.; Solbrig, C.W.; Gidaspow, D.

1982-01-01

A numerical solution for laminar flow heat transfer between a flowing gas and its containing rectangular duct has been obtained for many different boundary conditions which may arise in nuclear waste repository ventilation corridors. The problem has been solved for the cases of insulation on no walls, one wall, two walls, and three walls with various finite resistances on the remaining walls. Simplifications are made to decouple the convective heat transfer problem from the far field conduction problem, but peripheral conduction is retained. Results have been obtained for several duct aspect ratios in the thermal entrance and in the fully developed regions, including the constant temperature cases. When one wall is insulated and the other three are at constant temperature, the maximum temperature occurs in the fluid rather than on the insulated wall. This maximum moves toward the insulated wall with increasing axial distance. Nusselt numbers for the same constant flux on all four walls with peripheral conduction lie in a narrow band bounded by zero and infinite peripheral conduction cases. A dimensionsless wall conduction group of four can be considered infinite for the purpose of estimating fully developed Nusselt numbers to within an accuracy of 3%. A decrease in wall and bulk temperatures by finite wall conduction has been demonstrated for the case of a black body radiation boundary condition. Nusselt numbers for the case of constant temperature on the top and bottom walls and constant heat flux on the side walls exhibited unexpected behavior. (orig.)

Forced convection heat transfer in rectangular ducts - general case of wall resistances and peripheral conduction for ventilation cooling of nuclear waste repositories

International Nuclear Information System (INIS)

Lyczkowski, R.W.; Solbrig, C.W.; Gidaspow, D.

1980-01-01

A numerical solution for laminar flow heat transfer between a flowing gas and its containing rectangular duct has been obtained for many different boundary conditions which may arise in nuclear waste repository ventilation corridors. The problem has been solved for the cases of insulation on no walls, one wall, two walls, and three walls with various finite resistances on the remaining walls. Simplifications are made to decouple the convective heat transfer problem for the far field conduction problem, but peripheral conduction is retained. Results have been obtained for several duct aspect ratios in the thermal entrance and in the fully developed regions, including the constant temperature cases. When one wall is insulated and the other three are at constant temperature, the maximum temperature occurs in the fluid rather than on the insulated wall. This maximum moves toward the insulated wall with increasing axial distance. Nusselt numbers for the same constant flux on all four walls with peripheral conduction lie in a narrow band bounded by zero and infinite peripheral conduction cases. A dimensionless wall conduction group of four can be considered infinite for the purpose of estimating fully developed Nusselt numbers to within an accuracy of 3%. A decrease in wall and bulk temperatures by finite wall conduction has been demonstrated for the case of a black body radiation boundary condition. Nusselt numbers for the case of constant temperature on the top and bottom walls and constant heat flux on the side walls exhibited unexpected behavior

Forced convection heat transfer in rectangular ducts - general case of wall resistances and peripheral conduction for ventilation cooling of nuclear waste repositories

Energy Technology Data Exchange (ETDEWEB)

Lyczkowski, R W [Institute of Gas Technology, Chicago, IL (USA); Solbrig, C W [EG and G Idaho, Inc., Idaho Falls (USA); Gidaspow, D [Illinois Inst. of Tech., Chicago (USA). Dept. of Chemical Engineering

1982-02-01

A numerical solution for laminar flow heat transfer between a flowing gas and its containing rectangular duct has been obtained for many different boundary conditions which may arise in nuclear waste repository ventilation corridors. The problem has been solved for the cases of insulation on no walls, one wall, two walls, and three walls with various finite resistances on the remaining walls. Simplifications are made to decouple the convective heat transfer problem from the far field conduction problem, but peripheral conduction is retained. Results have been obtained for several duct aspect ratios in the thermal entrance and in the fully developed regions, including the constant temperature cases. When one wall is insulated and the other three are at constant temperature, the maximum temperature occurs in the fluid rather than on the insulated wall. This maximum moves toward the insulated wall with increasing axial distance. Nusselt numbers for the same constant flux on all four walls with peripheral conduction lie in a narrow band bounded by zero and infinite peripheral conduction cases. A dimensionsless wall conduction group of four can be considered infinite for the purpose of estimating fully developed Nusselt numbers to within an accuracy of 3%. A decrease in wall and bulk temperatures by finite wall conduction has been demonstrated for the case of a black body radiation boundary condition. Nusselt numbers for the case of constant temperature on the top and bottom walls and constant heat flux on the side walls exhibited unexpected behavior.

Rotational temperature measurement of NO gas using two-photon excitation spectrum

Science.gov (United States)

Ozaki, Tadao; Matsui, Yoshihiko; Ohsawa, Toshihiko

1981-04-01

The rotational temperature of nitric oxide gas has been measured by means of a single-beam two-photon excitation spectrum method using a pulsed continuously tunable dye laser. The nitric oxide gas was enclosed at about 40 Torr in a quartz cell which was put in an electric oven. The NO γ (0-0) band and R11+Q21 branches were used to obtain the two-photon excitation spectrum. The rotational temperatures were determined using the fact that molecules are distributed in the rotational levels according to the Boltzmann law. The temperature range was from room temperature to about 470 K. Observed temperatures were in good agreement with cell temperatures which were obtained by using a thermocouple.

A Smart Gas Sensor Insensitive to Humidity and Temperature Variations

International Nuclear Information System (INIS)

Hajmirzaheydarali, Mohammadreza; Ghafarinia, Vahid

2011-01-01

The accuracy of the quantitative sensing of volatile organic compounds by chemoresistive gas sensors suffers from the fluctuations in the background atmospheric conditions. This is caused by the drift-like terms introduced in the responses by these instabilities, which should be identified and compensated. Here, a mathematical model is presented for a specific chemoresistive gas sensor, which facilitates these identification and compensation processes. The resistive gas sensor was considered as a multi-input-single-output system. Along with the steady state value of the measured sensor resistance, the ambient humidity and temperature are the inputs to the system, while the concentration level of the target gas is the output. The parameters of the model were calculated based on the experimental database. The model was simulated by the utilization of an artificial neural network. This was connected to the sensor and could deliver the correct contamination level upon receiving the measured gas response, ambient humidity and temperature.

Analytical solutions for the temperature field in a 2D incompressible inviscid flow through a channel with walls of solid fuel

Directory of Open Access Journals (Sweden)

Sorin BERBENTE

2011-12-01

Full Text Available A gas (oxidizer flows between two parallel walls of solid fuel. A combustion is initiated: the solid fuel is vaporized and a diffusive flame occurs. The hot combustion products are submitted both to thermal diffusion and convection. Analytical solutions can be obtained both for the velocity and temperature distributions by considering an equivalent mean temperature where the density and the thermal conductivity are evaluated. The main effects of heat transfer are due to heat convection at the flame. Because the detailed mechanism of the diffusion flame is not introduced the reference chemical reaction is the combustion of premixed fuel with oxidizer in excess. In exchange the analytical solution is used to define an ideal quasi-uniform combustion that could be realized by an n adequate control. The given analytical closed solutions prove themselves flexible enough to adjust the main data of some existing experiments and to suggest new approaches to the problem.

Criteria of assessment for local wall thickness reductions in operative high-pressure gas pipelines; Beurteilungskriterien fuer lokale Wanddickenminderungen an in Betrieb befindlichen Gashochdruckleitungen

Energy Technology Data Exchange (ETDEWEB)

Hass, Georg [NetzDienste Rhein/Main GmbH, Frankfurt am Main (Germany); Hoffman, Ulrich [VNG - Verbundnetz Gas AG, Leipzig (Germany); Konarske, Juergen [RWE Westfalen-Weser-Ems Netzservice GmbH, Recklinghausen (Germany); Soppa, Thorsten [NG Netz Gas+Wasser (Germany). Bau/Betrieb Hochdrucknetz; Steiner, Michael [Open Grid Europe GmbH, Essen (Germany). Integritaet/Werkstofftechnik

2011-07-01

TUeV Nord, Salzgitter Mannesmann Forschung and DVGW investigated methods to assess local wall thickness reductions in operative high-pressure gas pipelines. Methods described in the relevant literature were reviewed with regard to the limiting criteria defined for maximum permissible wall thickness reductions. On the basis of this literature study and additional calculations, a comparative evaluation of the available methods was made. Several methods were identified that are compatible with the existing safety concept and general availability. It was found that - nearly independent of the method - burst safeties of 1.8 to 2.0 were used. The ultimate goal is the development of a German standard evaluation concept for local wall thickness reductions in high-pressure gas pipelines in order to avoid uncertainties and/or misinterpretations.

IAEA high temperature gas-cooled reactor activities

International Nuclear Information System (INIS)

Kendall, J.M.

2000-01-01

The IAEA activities on high temperature gas-cooled reactors are conducted with the review and support of the Member states, primarily through the International Working Group on Gas-Cooled Reactors (IWG-GCR). This paper summarises the results of the IAEA gas-cooled reactor project activities in recent years along with ongoing current activities through a review of Co-ordinated Research Projects (CRPs), meetings and other international efforts. A series of three recently completed CRPs have addressed the key areas of reactor physics for LEU fuel, retention of fission products and removal of post shutdown decay heat through passive heat transport mechanisms. These activities along with other completed and ongoing supporting CRPs and meetings are summarised with reference to detailed documentation of the results. (authors)

IAEA high temperature gas cooled reactor activities

International Nuclear Information System (INIS)

Kendall, J.M.

2001-01-01

IAEA activities on high temperature gas cooled reactors are conducted with the review and support of Member States, primarily through the International Working Group on Gas Cooled Reactors (IWGGCR). This paper summarises the results of the IAEA gas cooled reactor project activities in recent years along with ongoing current activities through a review of Co-ordinated Research Projects (CRPs), meetings and other international efforts. A series of three recently completed CRPs have addressed the key areas of reactor physics for LEU fuel, retention of fission products, and removal of post shutdown decay heat through passive heat transport mechanisms. These activities along with other completed and ongoing supporting CRPs and meetings are summarised with reference to detailed documentation of the results. (author)

Operational Windows for Dry-Wall and Wetted-Wall IFE Chambers

International Nuclear Information System (INIS)

Najmabadi, F.; Raffray, A.R.; Bromberg, L.

2004-01-01

The ARIES-IFE study was an integrated study of inertial fusion energy (IFE) chambers and chamber interfaces with the driver and target systems. Detailed analysis of various subsystems was performed parametrically to uncover key physics/technology uncertainties and to identify constraints imposed by each subsystem. In this paper, these constraints (e.g., target injection and tracking, thermal response of the first wall, and driver propagation and focusing) were combined to understand the trade-offs, to develop operational windows for chamber concepts, and to identify high-leverage research and development directions for IFE research. Some conclusions drawn in this paper are (a) the detailed characterization of the target yield and spectrum has a major impact on the chamber; (b) it is prudent to use a thin armor instead of a monolithic first wall for dry-wall concepts; (c) for dry-wall concepts with direct-drive targets, the most stringent constraint is imposed by target survival during the injection process; (d) for relatively low yield targets (<250 MJ), an operational window with no buffer gas may exist; (e) for dry-wall concepts with indirect-drive targets, a high buffer gas pressure would be necessary that may preclude propagation of the laser driver and require assisted pinch transport for the heavy-ion driver; and (f) generation and transport of aerosols in the chamber is the key feasibility issue for wetted-wall concepts

Experimental validation of error in temperature measurements in thin walled ductile iron castings

DEFF Research Database (Denmark)

Pedersen, Karl Martin; Tiedje, Niels Skat

2007-01-01

An experimental analysis has been performed to validate the measurement error of cooling curves measured in thin walled ductile cast iron. Specially designed thermocouples with Ø0.2 mm thermocouple wire in Ø1.6 mm ceramic tube was used for the experiments. Temperatures were measured in plates...

Composition of the C6+ Fraction of Natural Gas by Multiple Porous Layer Open Tubular Capillaries Maintained at Low Temperatures.

Science.gov (United States)

Burger, Jessica L; Lovestead, Tara M; Bruno, Thomas J

2016-03-17

As the sources of natural gas become more diverse, the trace constituents of the C 6 + fraction are of increasing interest. Analysis of fuel gas (including natural gas) for compounds with more than 6 carbon atoms (the C 6 + fraction) has historically been complex and expensive. Hence, this is a procedure that is used most often in troubleshooting rather than for day-to-day operations. The C 6 + fraction affects gas quality issues and safety considerations such as anomalies associated with odorization. Recent advances in dynamic headspace vapor collection can be applied to this analysis and provide a faster, less complex alternative for compositional determination of the C 6 + fraction of natural gas. Porous layer open tubular capillaries maintained at low temperatures (PLOT-cryo) form the basis of a dynamic headspace sampling method that was developed at NIST initially for explosives in 2009. This method has been recently advanced by the combining of multiple PLOT capillary traps into one "bundle," or wafer, resulting in a device that allows the rapid trapping of relatively large amounts of analyte. In this study, natural gas analytes were collected by flowing natural gas from the laboratory (gas out of the wall) or a prepared surrogate gas flowing through a chilled wafer. The analytes were then removed from the PLOT-cryo wafer by thermal desorption and subsequent flushing of the wafer with helium. Gas chromatography (GC) with mass spectrometry (MS) was then used to identify the analytes.

Transient fission gas release from UO2 fuel for high temperature and high burnup

International Nuclear Information System (INIS)

Szuta, M.

2001-01-01

In the present paper it is assumed that the fission gas release kinetics from an irradiated UO 2 fuel for high temperature is determined by the kinetics of grain growth. A well founded assumption that Vitanza curve describes the change of uranium dioxide re-crystallization temperature and the experimental results referring to the limiting grain size presented in the literature are used to modify the grain growth model. Algorithms of fission gas release due to re-crystallization of uranium dioxide grains are worked out. The defect trap model of fission gas behaviour described in the earlier papers is supplemented with the algorithms. Calculations of fission gas release in function of time, temperature, burn-up and initial grain sizes are obtained. Computation of transient fission gas release in the paper is limited to the case where steady state of irradiation to accumulate a desired burn-up is performed below the temperature of re-crystallization then the subsequent step temperature increase follows. There are considered two kinds of step temperature increase for different burn-up: the final temperature of the step increase is below and above the re-crystallization temperature. Calculations show that bursts of fission gas are predicted in both kinds. The release rate of gas liberated for the final temperature above the re-crystallization temperature is much higher than for final temperature below the re-crystallization temperature. The time required for the burst to subside is longer due to grain growth than due to diffusion of bubbles and knock-out release. The theoretical results explain qualitatively the experimental data but some of them need to be verified since this sort of experimental data are not found in the available literature. (author)

Basin-Wide Temperature Constraints On Gas Hydrate Stability In The Gulf Of Mexico

Science.gov (United States)

MacDonald, I. R.; Reagan, M. T.; Guinasso, N. L.; Garcia-Pineda, O. G.

2012-12-01

Gas hydrate deposits commonly occur at the seafloor-water interface on marine margins. They are especially prevalent in the Gulf of Mexico where they are associated with natural oil seeps. The stability of these deposits is potentially challenged by fluctuations in bottom water temperature, on an annual time-scale, and under the long-term influence of climate change. We mapped the locations of natural oil seeps where shallow gas hydrate deposits are known to occur across the entire Gulf of Mexico basin based on a comprehensive review of synthetic aperture radar (SAR) data (~200 images). We prepared a bottom water temperature map based on the archive of CTD casts from the Gulf (~6000 records). Comparing the distribution of gas hydrate deposits with predicted bottom water temperature, we find that a broad area of the upper slope lies above the theoretical stability horizon for structure 1 gas hydrate, while all sites where gas hydrate deposits occur are within the stability horizon for structure 2 gas hydrate. This is consistent with analytical results that structure 2 gas hydrates predominate on the upper slope (Klapp et al., 2010), where bottom water temperatures fluctuate over a 7 to 10 C range (approx. 600 m depth), while pure structure 1 hydrates are found at greater depths (approx. 3000 m). Where higher hydrocarbon gases are available, formation of structure 2 gas hydrate should significantly increase the resistance of shallow gas hydrate deposits to destabilizing effects variable or increasing bottom water temperature. Klapp, S.A., Bohrmann, G., Kuhs, W.F., Murshed, M.M., Pape, T., Klein, H., Techmer, K.S., Heeschen, K.U., and Abegg, F., 2010, Microstructures of structure I and II gas hydrates from the Gulf of Mexico: Marine and Petroleum Geology, v. 27, p. 116-125.Bottom temperature and pressure for Gulf of Mexico gas hydrate outcrops and stability horizons for sI and sII hydrate.

Background gas density and beam losses in NIO1 beam source

Energy Technology Data Exchange (ETDEWEB)

Sartori, E., E-mail: emanuele.sartori@igi.cnr.it; Veltri, P.; Serianni, G. [Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), C.so Stati Uniti 4, 35127 Padova (Italy); Cavenago, M. [INFN-LNL, v.le dell’Università 2, I-35020 Legnaro (PD) (Italy)

2016-02-15

NIO1 (Negative Ion Optimization 1) is a versatile ion source designed to study the physics of production and acceleration of H- beams up to 60 keV. In ion sources, the gas is steadily injected in the plasma source to sustain the discharge, while high vacuum is maintained by a dedicated pumping system located in the vessel. In this paper, the three dimensional gas flow in NIO1 is studied in the molecular flow regime by the Avocado code. The analysis of the gas density profile along the accelerator considers the influence of effective gas temperature in the source, of the gas temperature accommodation by collisions at walls, and of the gas particle mass. The calculated source and vessel pressures are compared with experimental measurements in NIO1 during steady gas injection.

Domain walls and perturbation theory in high-temperature gauge theory: SU(2) in 2+1 dimensions

International Nuclear Information System (INIS)

Korthals Altes, C.; Michels, A.; Teper, M.; Stephanov, M.

1997-01-01

We study the detailed properties of Z 2 domain walls in the deconfined high-temperature phase of the d=2+1 SU(2) gauge theory. These walls are studied both by computer simulations of the lattice theory and by one-loop perturbative calculations. The latter are carried out both in the continuum and on the lattice. We find that leading order perturbation theory reproduces the detailed properties of these domain walls remarkably accurately even at temperatures where the effective dimensionless expansion parameter g 2 /T is close to unity. The quantities studied include the surface tension, the action density profiles, roughening, and the electric screening mass. It is only for the last quantity that we find an exception to the precocious success of perturbation theory. All this shows that, despite the presence of infrared divergences at higher orders, high-T perturbation theory can be an accurate calculational tool. copyright 1997 The American Physical Society

Batch-processed carbon nanotube wall as pressure and flow sensor

International Nuclear Information System (INIS)

Choi, Jungwook; Kim, Jongbaeg

2010-01-01

A pressure and flow sensor based on the electrothermal-thermistor effect of a batch-processed carbon nanotube wall (CNT wall) is presented. The negative temperature coefficient of resistance (TCR) of CNTs and the temperature dependent tunneling rate through the CNT/silicon junction enable vacuum pressure and flow velocity sensing because the heat transfer rate between CNTs and the surrounding gas molecules differs depending on pressure and flow rate. The CNT walls are synthesized by thermal chemical vapor deposition (CVD) on an array of microelectrodes fabricated on a silicon-on-insulator (SOI) wafer. The CNTs are self-assembled between the microelectrodes and substrate across the thickness of a buried oxide layer during the synthesis process, and the simple batch fabrication results in high throughput and yield. A wide pressure range, down to 3 x 10 -3 from 10 5 Pa, and a nitrogen flow velocity range between 1 and 52.4 mm s -1 , are sensed. Further experimental characterizations of the bias voltage dependent response of the sensor as a vacuum pressure gauge are presented.

Infrared temperature and gas measurements at the Haderslev power and heat plan[Denmark]; Infraroede temperatur- og gasmaelinger Haderslev Kraftvarmevaerk

Energy Technology Data Exchange (ETDEWEB)

Clausen, Soennik

2007-04-15

Report describe results from a two week measurement campaign at Haderslev Kraftvarmevaerk in 2006 as a part of PSO-project 5727 'On-line optimization of waste incinerators'. Non-contact gas temperature and gas composition was measured simultaneously with a FTIR spectrometer coupled to a water-cooled fiber-optic probe. Gas temperature and H{sub 2}O, CO{sub 2}, CO, C{sub x}H{sub y} and HCl concentrations was extracted from measured spectra of emitted thermal radiation from gas slab over a 25 cm path. Measurements where performed in different positions to obtain a overview of flow behavior and conditions during stable operation and during a step in operation conditions, e.g. changing combustion air flows. Furthermore, surface temperature of grate was monitored with a thermal camera and a cross stack reference measurement on hot outlet gas was performed with a FTIR spectrometer. (au)

In-duct removal of mercury from coal-fired power plant flue gas by activated carbon: assessment of entrained flow versus wall surface contributions

Energy Technology Data Exchange (ETDEWEB)

Scala, F.; Chirone, R.; Lancia, A. [CNR, Naples (Italy). Institute for Research on Combustion

2008-12-15

In-duct mercury capture efficiency by activated carbon from coal-combustion flue gas was investigated. To this end, elemental mercury capture experiments were conducted at 100 C in a purposely designed 65-mm ID labscale pyrex apparatus operated as an entrained flow reactor. Gas residence times were varied between 0.7 and 2.0 s. Commercial-powdered activated carbon was continuously injected in the reactor and both mercury concentration and carbon elutriation rate were followed at the outlet. Transient mercury concentration profiles at the outlet showed that steady-state conditions were reached in a time interval of 15-20 min, much longer than the gas residence time in the reactor. Results indicate that the influence of the walls is non-negligible in determining the residence time of fine carbon particles in the adsorption zone, because of surface deposition and/or the establishment of a fluid-dynamic boundary layer near the walls. Total mercury capture efficiencies of 20-50% were obtained with carbon injection rates in the range 0.07-0.25 g/min. However, only a fraction of this capture was attributable to free-flowing carbon particles, a significant contribution coming from activated carbon staying near the reactor walls. Entrained bed experiments at lab-scale conditions are probably not properly representative of full-scale conditions, where the influence of wall interactions is lower. Moreover, previously reported entrained flow lab-scale mercury capture data should be reconsidered by taking into account the influence of particle-wall interactions.

Design and development of gas turbine high temperature reactor 300 (GTHTR300)

International Nuclear Information System (INIS)

Kunitomi, Kazuhiko; Katanishi, Shoji; Takada, Shoji; Takizuka, Takakazu; Yan, Xing; Kosugiyama, Shinichi

2003-01-01

JAERI (Japan Atomic Energy Research Institute) started design and development of the high temperature gas cooled reactor with a gas turbine electric generation system, GTHTR300, in April 2001. Design originalities of the GTHTR300 are a horizontally mounted highly efficient gas turbine system and an ultimately simplified safety system such as no containment building and no active emergency core cooling. These design originalities are proposed based on design and operational experiences in conventional gas turbine systems and Japan's first high temperature gas cooled reactor (HTTR: High Temperature Engineering Test Reactor) so that many R and Ds are not required for the development. Except these original design features, devised core design, fuel design and plant design are adopted to meet design requirements and attain a target cost. This paper describes the unique design features focusing on the safety design, reactor core design and gas turbine system design together with a preliminary result of the safety evaluation carried out for a typical severe event. This study is entrusted from Ministry of Education, Culture, Sports, Science and Technology of Japan. (author)

Experimental Study of Natural Gas Temperature Effects on the Flame Luminosity and No Emission

Directory of Open Access Journals (Sweden)

S. M. Javadi

2012-06-01

Full Text Available The flame radiation enhancement in gas-fired furnaces significantly improves the thermal efficiency without significantly affecting the NOx emissions. In this paper, the effects of inlet natural gas preheating on the flame luminosity, overall boiler efficiency, and NO emission in a 120 kW boiler have been investigated experimentally. Flame radiation is measured by use of laboratory pyranometer with photovoltaic sensor. A Testo350XL gas analyzer is also used for measuring the temperature and combustion species. The fuel is preheated from the room temperature to 350°C. The experimental measurements show that the preheating of natural gas up to about 240°C has no considerable effect on the flame luminosity. The results show that increasing the inlet gas temperature from 240°C, abruptly increases the flame luminosity. This luminosity increase enhances the boiler efficiency and also causes significant reduction in flame temperature and NO emission. The results show that increasing the inlet gas temperature from 240°C to 300°C increases the flame luminous radiation by 60% and boiler efficiency by 20%; while the maximum flame temperature and the boiler NO emission show a 10% and 8% decrease respectively.

Diagnostic techniques for measuring temperature transients and stress transients in the first wall of an ICF reactor

International Nuclear Information System (INIS)

Melamed, N.T.; Taylor, L.H.

1983-01-01

The primary challenge in the design of an Inertial Confinement Fusion (ICF) power reactor is to make the first wall survive the frequent explosions of the pellets. Westinghouse has proposed a dry wall design consisting of steel tubes coated with tantalum. This report describes the design of a test chamber and two diagnostic procedures for experimentally determining the reliability of the Westinghouse design. The test chamber simulates the x-ray and ion pulse irradiation of the wall due to a pellet explosion. The diagnostics consist of remote temperature sensing and surface deformation measurements. The chamber and diagnostics can also be used to test other first-wall designs

Gravitational collapse of a magnetized fermion gas with finite temperature

Energy Technology Data Exchange (ETDEWEB)

Delgado Gaspar, I. [Instituto de Geofisica y Astronomia (IGA), La Habana (Cuba); Perez Martinez, A. [Instituto de Cibernetica, Matematica y Fisica (ICIMAF), La Habana (Cuba); Sussman, Roberto A. [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico (ICN-UNAM), Mexico (Mexico); Ulacia Rey, A. [Instituto de Cibernetica, Matematica y Fisica (ICIMAF), La Habana (Cuba); Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico (ICN-UNAM), Mexico (Mexico)

2013-07-15

We examine the dynamics of a self-gravitating magnetized fermion gas at finite temperature near the collapsing singularity of a Bianchi-I spacetime. Considering a general set of appropriate and physically motivated initial conditions, we transform Einstein-Maxwell field equations into a complete and self-consistent dynamical system amenable for numerical work. The resulting numerical solutions reveal the gas collapsing into both, isotropic (''point-like'') and anisotropic (''cigar-like''), singularities, depending on the initial intensity of the magnetic field. We provide a thorough study of the near collapse behavior and interplay of all relevant state and kinematic variables: temperature, expansion scalar, shear scalar, magnetic field, magnetization, and energy density. A significant qualitative difference in the behavior of the gas emerges in the temperature range T/m{sub f} {proportional_to} 10{sup -6} and T/m{sub f} {proportional_to} 10{sup -3}. (orig.)

Contribution to high-temperature chromatography and high-temperature-gas-chromatography-mass spectrometry of lipids

International Nuclear Information System (INIS)

Aichholz, R.

1998-04-01

This thesis describes the use of high temperature gas chromatography for the investigation of unusual triacylglycerols, cyanolipids and bees waxes. The used glass capillary columns were pretreated and coated with tailor made synthesized high temperature stable polysiloxane phases. The selective separation properties of the individual columns were tested with a synthetic lipid mixture. Suitable derivatization procedures for the gaschromatographic analyses of neutral lipids, containing multiple bonds as well as hydroxy-, epoxy-, and carboxyl groups, were developed and optimized. Therefore conjugated olefinic-, conjugated olefinic-acetylenic-, hydroxy-, epoxy-, and conjugated olefinic keto triacylglycerols in miscellaneous plant seed oils as well as hydroxy monoesters, diesters and hydroxy diesters in bees waxes could be analysed directly with high temperature gas chromatography for the first time. In order to elucidate the structures of separated lipid compounds, high temperature gas chromatography was coupled to mass spectrometry and tandem mass spectrometry, respectively. Comparable analytical systems are hitherto not commercial available. Therefore instrumental prerequisites for a comprehensive and detailed analysis of seed oils and bees waxes were established. In GC/MS commonly two ionization methods are used, electron impact ionization and chemical ionization. For the analysis of lipids the first is of limited use only. Due to intensive fragmentation only weak molecular ions are observed. In contrast, the chemical ionization yields in better results. Dominant quasi molecular ions enable an unambiguous determination of the molecular weight. Moreover, characteristic fragment ions provide important indications of certain structural features of the examined compounds. Nevertheless, in some cases the chromatographic resolution was insufficient in order to separate all compounds present in natural lipid mixtures. Owing to the selected detection with mass spectrometry

On the sensitivity of a helicopter combustor wall temperature to convective and radiative thermal loads

International Nuclear Information System (INIS)

Berger, S.; Richard, S.; Duchaine, F.; Staffelbach, G.; Gicquel, L.Y.M.

2016-01-01

Highlights: • Coupling of LES, DOM and conduction is applied to an industrial combustor. • Thermal sensitivity of the combustor to convection and radiation is investigated. • CHT based on LES is feasible in an industrial context with acceptable CPU costs. • Radiation heat fluxes are of the same order of magnitude that the convective ones. • CHT with radiation are globally in good agreement with thermocolor test. - Abstract: The design of aeronautical engines is subject to many constraints that cover performance gain as well as increasingly sensitive environmental issues. These often contradicting objectives are currently being answered through an increase in the local and global temperature in the hot stages of the engine. As a result, hot spots could appear causing a premature aging of the combustion chamber. Today, the characterization of wall temperatures is performed experimentally by complex thermocolor tests in advanced phases of the design process. To limit such expensive experiments and integrate the knowledge of the thermal environment earlier in the design process, efforts are currently performed to provide high fidelity numerical tools able to predict the combustion chamber wall temperature including the main physical phenomena: combustion, convection and mixing of hot products and cold flows, radiative transfers as well as conduction in the solid parts. In this paper, partitioned coupling approaches based on a Large Eddy Simulation (LES) solver, a Discrete Ordinate Method radiation solver and an unsteady conduction code are used to investigate the sensitivity of an industrial combustor thermal environment to convection and radiation. Four computations including a reference adiabatic fluid only simulation, Conjugate Heat Transfer, Radiation-Fluid Thermal Interaction and fully coupled simulations are performed and compared with thermocolor experimental data. From the authors knowledge, such comparative study with LES has never been published. It

High temperature gas cleaning for pressurized gasification. Final report

Energy Technology Data Exchange (ETDEWEB)

Alden, H.; Hagstroem, P.; Hallgren, A.; Waldheim, L. [TPS Termiska Processer AB, Nykoeping (Sweden)

2000-04-01

The purpose of the project was to build an apparatus to study pressurized, high temperature gas cleaning of raw gasification gas generated from biomass. A flexible and easy to operate pressurized apparatus was designed and installed for the investigations in high temperature gas cleaning by means of thermal, catalytic or chemical procedures. A semi continuos fuel feeding concept, at a maximum rate of 700 g/h, allowed a very constant formation of a gas product at 700 deg C. The gas product was subsequently introduced into a fixed bed secondary reactor where the actual gas cleanup or reformation was fulfilled. The installation work was divided into four work periods and apart from a few delays the work was carried out according to the time plan. During the first work period (January - June 1994) the technical design, drawings etc. of the reactor and additional parts were completed. All material for the construction was ordered and the installation work was started. The second work period (July - December 1994) was dedicated to the construction and the installation of the different components. Initial tests with the electrical heating elements, control system and gas supply were assigned to the third work period (January - June 1995). After the commissioning and the resulting modifications, initial pyrolysis and tar decomposition experiments were performed. During the fourth and final work period, (June - December 1995) encouraging results from first tests allowed the experimental part of the project work to commence, however in a slightly reduced program. The experimental part of the project work comparatively studied tar decomposition as a function of the process conditions as well as of the choice of catalyst. Two different catalysts, dolomite and a commercial Ni-based catalyst, were evaluated in the unit. Their tar cracking ability in the pressure interval 1 - 20 bar and at cracker bed temperatures between 800 - 900 deg C was compared. Long term tests to study

Photon antibunching in single-walled carbon nanotubes at telecommunication wavelengths and room temperature

Energy Technology Data Exchange (ETDEWEB)

Endo, Takumi, E-mail: endou@az.appi.keio.ac.jp; Ishi-Hayase, Junko; Maki, Hideyuki, E-mail: maki@appi.keio.ac.jp [Department of Applied Physics and Physico-Informatics, Keio University, Yokohama 223-8522 (Japan)

2015-03-16

We investigated the photoluminescence of individual air-suspended single-walled carbon nanotubes (SWNTs) from 6 to 300 K. Time-resolved and antibunching measurements over the telecommunication wavelength range were performed using a superconducting single-photon detector. We detected moderate temperature independent antibunching behavior over the whole temperature range studied. To investigate the exciton dynamics, which is responsible for the antibunching behavior, we measured excitation-power and temperature dependence of the photoluminescence spectra and lifetime decay curves. These measurements suggested an exciton confinement effect that is likely caused by high-dielectric amorphous carbon surrounding the SWNTs. These results indicate that SWNTs are good candidates for light sources in quantum communication technologies operating in the telecommunication wavelength range and at room temperature.

A condensation experiment in the accumulated conditions of noncondensable gas in a vertical tube

International Nuclear Information System (INIS)

Lee, Kwon Yeong; Kim, Moo Hwan

2005-01-01

accumulated noncondensable gas in the vertical tube. The experimental facility consisted of steam generation part, steam flow rate control part, steam-noncondensable gas mixing part, test section with a condensing tube submerged in a water pool, and venting and draining part. The heat flux and heat transfer coefficient were estimated from two temperature differences between inner and outer wall temperature, and between inner wall and mixture bulk temperature. It was estimated that the system uncertainty could be mainly originated from the uncertainty of inner wall temperature. So the method using heater wire was developed to correct the depth of thermocouples inserted to measure the inner wall temperatures. The local condensation heat transfer coefficients inside the vertical tube were measured in the presence of accumulated nitrogen. The heat transfer coefficients decreased as the nitrogen volumetric fraction inside the condenser tube increased. The average heat flux increased as the inlet temperature and the inlet mixture Reynolds number increased. It could be roughly estimated the distribution of nitrogen inside the vertical tube from the local condensation heat transfer coefficients. (authors)

Deuterium to helium plasma-wall change-over experiments in the JET MkII-gas box divertor

International Nuclear Information System (INIS)

Hillis, D.L.; Loarer, T.; Bucalossi, J.; Pospieszczyk, A.; Fundamenski, W.; Matthews, G.; Meigs, A.; Morgan, P.; Phillips, V.; Pitts, R.; Stamp, M.; Hellermann, M. von

2003-01-01

The deuterium and helium dynamics in the plasma and subdivertor regions of JET are compared during a sequence of similar ohmic and ICRH pulses where 100% He gas is injected into the JET vacuum vessel, whose graphite walls were previously saturated with deuterium. After the first six He fueled change-over discharges, only He plasma operation was performed. Following this investigation, the situation is reversed and the change-over from an initially saturated He wall is investigated when only D 2 plasma fuelling is used. The He concentration is measured in the subdivertor with a species selective Penning gauge. Comparison of the time dependence of the divertor concentrations with those at the edge and strike point shows significant differences during the first six discharges. This difference along with a global He particle balance is used to assess the status of the wall saturation over the initial 6-7 He change-over discharges

Severe water ingress accident analysis for a Modular High Temperature Gas Cooled Reactor

International Nuclear Information System (INIS)

Zhang Zuoyi; Scherer, Winfried

1997-01-01

This paper analyzes the severe water ingress accidents in the SIEMENS 200MW Modular High Temperature Gas Cooled Reactor (HTR-Module) under the assumption of no active safety protection systems in order to find the safety margin of the current HTR-Module design. A water, steam and helium multi-phase cavity model is originally developed and implemented in the DSNP simulation system. The developed DSNP system is used to simulate the primary circuit of HTR-Module power plant. The comparisons of the models with the TINTE calculations validate the current simulation. After analyzing the effects of blower separation on water droplets, the wall heat storage, etc., it is found that the maximum H 2 O density increase rate in the reactor core is smaller than 0.3 kg/(m 3 s). The liquid water vaporization in the steam generator and H 2 O transport from the steam generator to the reactor core reduces the impulse of the H 2 O in the reactor core. The nuclear reactivity increase caused by the water ingress leads to a fast power excursion, which, however, is inherently counterbalanced by negative feedback effects. Concerning the integrity of the fuel elements, the safety relevant temperature limit of 1600degC was not reached in any case. (author)

Bose-Einstein condensation of photons in a 'white-wall' photon box

International Nuclear Information System (INIS)

Klaers, Jan; Schmitt, Julian; Vewinger, Frank; Weitz, Martin

2011-01-01

Bose-Einstein condensation, the macroscopic ground state occupation of a system of bosonic particles below a critical temperature, has been observed in cold atomic gases and solid-state physics quasiparticles. In contrast, photons do not show this phase transition usually, because in Planck's blackbody radiation the particle number is not conserved and at low temperature the photons disappear in the walls of the system. Here we report on the realization of a photon Bose-Einstein condensate in a dye-filled optical microcavity, which acts as a 'white-wall' photon box. The cavity mirrors provide a trapping potential and a non-vanishing effective photon mass, making the system formally equivalent to a two-dimensional gas of trapped massive bosons. Thermalization of the photon gas is reached in a number conserving way by multiple scattering off the dye molecules. Signatures for a BEC upon increased photon density are: a spectral distribution that shows Bose-Einstein distributed photon energies with a macroscopically populated peak on top of a broad thermal wing, the observed threshold of the phase transition showing the predicted absolute value and scaling with resonator geometry, and condensation appearing at the trap centre even for a spatially displaced pump spot.

Bose-Einstein condensation of photons in a 'white-wall' photon box

Science.gov (United States)

Klärs, Jan; Schmitt, Julian; Vewinger, Frank; Weitz, Martin

2011-01-01

Bose-Einstein condensation, the macroscopic ground state occupation of a system of bosonic particles below a critical temperature, has been observed in cold atomic gases and solid-state physics quasiparticles. In contrast, photons do not show this phase transition usually, because in Planck's blackbody radiation the particle number is not conserved and at low temperature the photons disappear in the walls of the system. Here we report on the realization of a photon Bose-Einstein condensate in a dye-filled optical microcavity, which acts as a "white-wall" photon box. The cavity mirrors provide a trapping potential and a non-vanishing effective photon mass, making the system formally equivalent to a two-dimensional gas of trapped massive bosons. Thermalization of the photon gas is reached in a number conserving way by multiple scattering off the dye molecules. Signatures for a BEC upon increased photon density are: a spectral distribution that shows Bose-Einstein distributed photon energies with a macroscopically populated peak on top of a broad thermal wing, the observed threshold of the phase transition showing the predicted absolute value and scaling with resonator geometry, and condensation appearing at the trap centre even for a spatially displaced pump spot.

High-temperature materials and structural ceramics

International Nuclear Information System (INIS)

1990-01-01

This report gives a survey of research work in the area of high-temperature materials and structural ceramics of the KFA (Juelich Nuclear Research Center). The following topics are treated: (1) For energy facilities: ODS materials for gas turbine blades and heat exchangers; assessment of the remaining life of main steam pipes, material characterization and material stress limits for First-Wall components; metallic and graphitic materials for high-temperature reactors. (2) For process engineering plants: composites for reformer tubes and cracking tubes; ceramic/ceramic joints and metal/ceramic and metal/metal joints; Composites and alloys for rolling bearing and sliding systems up to application temperatures of 1000deg C; high-temperature corrosion of metal and ceramic material; porous ceramic high-temperature filters and moulding coat-mix techniques; electrically conducting ceramic material (superconductors, fuel cells, solid electrolytes); high-temperature light sources (high-temperature chemistry); oil vapor engines with caramic components; ODS materials for components in diesel engines and vehicle gas turbines. (MM) [de

Plasmonic nanocomposite thin film enabled fiber optic sensors for simultaneous gas and temperature sensing at extreme temperatures.

Science.gov (United States)

Ohodnicki, Paul R; Buric, Michael P; Brown, Thomas D; Matranga, Christopher; Wang, Congjun; Baltrus, John; Andio, Mark

2013-10-07

Embedded sensors capable of operation in extreme environments including high temperatures, high pressures, and highly reducing, oxidizing and/or corrosive environments can make a significant impact on enhanced efficiencies and reduced greenhouse gas emissions of current and future fossil-based power generation systems. Relevant technologies can also be leveraged in a wide range of other applications with similar needs including nuclear power generation, industrial process monitoring and control, and aviation/aerospace. Here we describe a novel approach to embedded sensing under extreme temperature conditions by integration of Au-nanoparticle based plasmonic nanocomposite thin films with optical fibers in an evanescent wave absorption spectroscopy configuration. Such sensors can potentially enable simultaneous temperature and gas sensing at temperatures approaching 900-1000 °C in a manner compatible with embedded and distributed sensing approaches. The approach is demonstrated using the Au/SiO2 system deposited on silica-based optical fibers. Stability of optical fibers under relevant high temperature conditions and interactions with changing ambient gas atmospheres is an area requiring additional investigation and development but the simplicity of the sensor design makes it potentially cost-effective and may offer a potential for widespread deployment.

High temperature, high pressure gas loop - the Component Flow Test Loop (CFTL)

International Nuclear Information System (INIS)

Gat, U.; Sanders, J.P.; Young, H.C.

1984-01-01

The high-pressure, high-temperature, gas-circulating Component Flow Test Loop located at Oak Ridge National Laboratory was designed and constructed utilizing Section III of the ASME Boiler and Pressure Vessel Code. The quality assurance program for operating and testing is also based on applicable ASME standards. Power to a total of 5 MW is available to the test section, and an air-cooled heat exchanger rated at 4.4 MW serves as heat sink. The three gas-bearing, completely enclosed gas circulators provide a maximum flow of 0.47 m 3 /s at pressures to 10.7 MPa. The control system allows for fast transients in pressure, power, temperature, and flow; it also supports prolonged unattended steady-state operation. The data acquisition system can access and process 10,000 data points per second. High-temperature gas-cooled reactor components are being tested

Global particle balance and wall recycling properties of long duration discharges on TRIAM-1M

International Nuclear Information System (INIS)

Sakamoto, M.; Yuno, M.; Itoh, S.

2003-01-01

The longest tokamak discharge with the duration of 11406 s (3 h 10 min) was achieved. The global particle balance has been investigated. In the longest discharge, the global balance between the particle absorption and release of the wall was achieved around t∼30 min and then the fueling was automatically stopped. After that the plasma density was maintained by the recycling flux alone until the end of the discharge. The maximum wall inventory is about 3.6 x 10 20 H at t ∼ 30 min but it is finally released from the wall at the end of the discharge. The global balance seems to be caused by the increase in the hydrogen release from the main chamber resulting from its temperature rise. Moreover, it has been observed a large difference between properties of wall recycling in the continuous gas feed case (i.e. static condition) and the additional gas puff case (i.e. dynamic condition). In the static condition, the effective particle confinement time increases almost linearly to about 10 s during the one-minute discharge. In the dynamic condition, the decay time of the electron density just after the gas puff, i.e. the effective particle confinement time, is 0.2 to 0.3 s during the one-minute discharge. The large difference was also reproduced in the longest discharge. It is considered that the enhanced wall pumping is caused by the increase in fluxes of the diffused ions and charge exchange neutrals due to the additional gas puff. (author)

Effect of temperature and α-irradiation on gas permeability for ...

Indian Academy of Sciences (India)

Unknown

polymer membranes that help separate gas. In addition to the chemical composition, the transport properties are related to the main characteristics of copolymers like the glass transition temperature, crystallinity and crosslink- ing ratio. Gas diffusion through polymers is related to the activation energy (Pesiri et al 2003).

High temperature gas dynamics an introduction for physicists and engineers

CERN Document Server

Bose, Tarit K

2014-01-01

High Temperature Gas Dynamics is a primer for scientists, engineers, and students who would like to have a basic understanding of the physics and the behavior of high-temperature gases. It is a valuable tool for astrophysicists as well. The first chapters treat the basic principles of quantum and statistical mechanics and how to derive thermophysical properties from them. Special topics are included that are rarely found in other textbooks, such as the thermophysical and transport properties of multi-temperature gases and a novel method to compute radiative transfer. Furthermore, collision processes between different particles are discussed. Separate chapters deal with the production of high-temperature gases and with electrical emission in plasmas, as well as related diagnostic techniques.This new edition adds over 100 pages and includes the following updates: several sections on radiative properties of high temperature gases and various radiation models, a section on shocks in magneto-gas-dynamics, a sectio...

The real gas behaviour of helium as a cooling medium for high-temperature reactors

International Nuclear Information System (INIS)

Hewing, G.

1977-01-01

The article describes the influence of the real gas behaviour on the variables of state for the helium gas and the effects on the design of high-temperature reactor plants. After explaining the basic equations for describing variables and changes of state of the real gas, the real and ideal gas behaviour is analysed. Finally, the influence of the real gas behaviour on the design of high-temperature reactors in one- and two-cycle plants is investigated. (orig.) [de

Influence of the gas mixture radio on the correlations between the excimer XeCl emission and the sealed gas temperature in dielectric barrier discharge lamps

CERN Document Server

Xu Jin Zhou; Ren Zhao Xing

2002-01-01

For dielectric barrier discharge lamps filled with various gas mixture ratios, the correlations between the excimer XeCl emission and the sealed gas temperature have been founded, and a qualitative explication is presented. For gas mixture with chlorine larger than 3%, the emission intensity increases with the sealed gas temperature, while with chlorine about 2%, the emission intensity decreases with the increasing in the gas temperature, and could be improved by cooling water. However, if chlorine is less than 1.5%, the discharge appears to be a mixture mode with filaments distributed in a diffused glow-like discharge, and the UV emission is independent on the gas temperature

Fuel arrangement for high temperature gas cooled reactor

International Nuclear Information System (INIS)

Tobin, J.M.

1978-01-01

Disclosed is a fuel arrangement for a high temperature gas cooled reactor including fuel assemblies with separate directly cooled fissile and fertile fuel elements removably inserted in an elongated moderator block also having a passageway for control elements

A method for calculating the gas volume proportions and inhalation temperature of inert gas mixtures allowing reaching normothermic or hypothermic target body temperature in the awake rat

Directory of Open Access Journals (Sweden)

Jacques H Abraini

2017-01-01

Full Text Available The noble gases xenon (Xe and helium (He are known to possess neuroprotective properties. Xe is considered the golden standard neuroprotective gas. However, Xe has a higher molecular weight and lower thermal conductivity and specific heat than those of nitrogen, the main diluent of oxygen (O2 in air, conditions that could impair or at least reduce the intrinsic neuroprotective properties of Xe by increasing the critical care patient's respiratory workload and body temperature. In contrast, He has a lower molecular weight and higher thermal conductivity and specific heat than those of nitrogen, but is unfortunately far less potent than Xe at providing neuroprotection. Therefore, combining Xe with He could allow obtaining, depending on the gas inhalation temperature and composition, gas mixtures with neutral or hypothermic properties, the latter being advantageous in term of neuroprotection. However, calculating the thermal properties of a mixture, whatever the substances – gases, metals, rubbers, etc. – is not trivial. To answer this question, we provide a graphical method to assess the volume proportions of Xe, He and O2 that a gas mixture should contain, and the inhalation temperature to which it should be administered to allow a clinician to maintain the patient at a target body temperature.

Modular high-temperature gas-cooled reactor

International Nuclear Information System (INIS)

Shepherd, L.R.

1988-01-01

The high financial risk involved in building large nuclear power reactors has been a major factor in halting investment in new plant and in bringing further technical development to a standstill. Increased public concern about the safety of nuclear plant, particularly after Chernobyl, has contributed to this stagnation. Financial and technical risk could be reduced considerably by going to small modular units, which would make it possible to build up power station capacity in small steps. Such modular plant, based on the helium-cooled high temperature reactor (HTR), offers remarkable advantages in terms of inherent safety characteristics, partly because of the relatively small size of the individual modules but more on account of the enormous thermal capacity and high temperature margins of the graphitic reactor assemblies. Assessments indicate that, in the USA, the cost of power from the modular systems would be less than that from conventional single reactor plant, up to about 600 MW(e), and only marginally greater above that level, a margin that should be offset by the shorter time required in bringing the modular units on line to earn revenue. The modular HTR would be particularly appropriate in the UK, because of the considerable British industrial background in gas-cooled reactors, and could be a suitable replacement for Magnox. The modular reactor would be particularly suited to combined heat and power schemes and would offer great potential for the eventual development of gas turbine power conversion and the production of high-temperature process heat. (author)

A Comparison of Thermal Models for Temperature Profiles in Gas-Lift Wells

Directory of Open Access Journals (Sweden)

Langfeng Mu

2018-02-01

Full Text Available Gas lift is a simple, reliable artificial lift method which is frequently used in offshore oil field developments. In order to enhance the efficiency of production by gas lift, it is vital to exactly predict the distribution of temperature-field for fluid within the wellbore. A new mechanistic model is developed for computing flowing fluid temperature profiles in both conduits simultaneously for a continuous-flow gas-lift operation. This model assumes steady heat transfer in the formation, as well as steady heat transfer in the conduits. A micro-units discrete from the wellbore, whose heat transfer process is analyzed and whose heat transfer equation is set up according to the law of conservation of energy. A simplified algebraic solution to our model is conducted to analyze the temperature profile. Sensitivity analysis was conducted with the new model. The results indicate that mass flow rate of oil and the tubing overall heat transfer coefficient are the main factors that influence the temperature distribution inside the tubing and that the mass flow rate of oil is the main factor affecting temperature distribution in the annulus. Finally, the new model was tested in three various wells and compared with other models. The results showed that the new model is more accurate and provides significant references for temperature prediction in gas lift well.

Role of plasma enhanced atomic layer deposition reactor wall conditions on radical and ion substrate fluxes

Energy Technology Data Exchange (ETDEWEB)

Sowa, Mark J., E-mail: msowa@ultratech.com [Ultratech/Cambridge NanoTech, 130 Turner Street, Building 2, Waltham, Massachusetts 02453 (United States)

2014-01-15

Chamber wall conditions, such as wall temperature and film deposits, have long been known to influence plasma source performance on thin film processing equipment. Plasma physical characteristics depend on conductive/insulating properties of chamber walls. Radical fluxes depend on plasma characteristics as well as wall recombination rates, which can be wall material and temperature dependent. Variations in substrate delivery of plasma generated species (radicals, ions, etc.) impact the resulting etch or deposition process resulting in process drift. Plasma enhanced atomic layer deposition is known to depend strongly on substrate radical flux, but film properties can be influenced by other plasma generated phenomena, such as ion bombardment. In this paper, the chamber wall conditions on a plasma enhanced atomic layer deposition process are investigated. The downstream oxygen radical and ion fluxes from an inductively coupled plasma source are indirectly monitored in temperature controlled (25–190 °C) stainless steel and quartz reactors over a range of oxygen flow rates. Etch rates of a photoresist coated quartz crystal microbalance are used to study the oxygen radical flux dependence on reactor characteristics. Plasma density estimates from Langmuir probe ion saturation current measurements are used to study the ion flux dependence on reactor characteristics. Reactor temperature was not found to impact radical and ion fluxes substantially. Radical and ion fluxes were higher for quartz walls compared to stainless steel walls over all oxygen flow rates considered. The radical flux to ion flux ratio is likely to be a critical parameter for the deposition of consistent film properties. Reactor wall material, gas flow rate/pressure, and distance from the plasma source all impact the radical to ion flux ratio. These results indicate maintaining chamber wall conditions will be important for delivering consistent results from plasma enhanced atomic layer deposition

X-ray and pressure conditions on the first wall of a particle beam inertial confinement reactor

International Nuclear Information System (INIS)

Magelssen, G.R.

1979-01-01

Because of the presence of a chamber gas in a particle beam reactor cavity, nonneutron target debris created from thermonuclear burn will be modified or stopped before it reaches the first reactor wall. The resulting modified spectra and pulse lengths of the debris need to be calculated to determine first wall effects. Further, the cavity overpressure created by the momentum and energy exchange between the debris and gas must also be calculated to determine its effect. The purpose of this paper is to present results of the debris-background gas problem obtained with a one fluid, two temperature plasma hydrodynamic computer code model which includes multifrequency radiation transport. Spherical symmetry, ideal gas equation of state, and LTE for each radiation frequency group were assumed. The transport of debris ions was not included and all the debris energy was assumed to be in radiation. The calculated x-ray spectra and pulse lengths and the background overpressure are presented

Axisymmetric wave propagation in gas shear flow confined by a rigid-walled pipeline

International Nuclear Information System (INIS)

Chen Yong; Huang Yi-Yong; Chen Xiao-Qian; Bai Yu-Zhu; Tan Xiao-Dong

2015-01-01

The axisymmetric acoustic wave propagating in a perfect gas with a shear pipeline flow confined by a circular rigid wall is investigated. The governing equations of non-isentropic and isentropic acoustic assumptions are mathematically deduced while the constraint of Zwikker and Kosten is relaxed. An iterative method based on the Fourier–Bessel theory is proposed to semi-analytically solve the proposed models. A comparison of numerical results with literature contributions validates the present contribution. Meanwhile, the features of some high-order transverse modes, which cannot be analyzed based on the Zwikker and Kosten theory, are analyzed (paper)

Nuclear power for coexistence with nature, high temperature gas-cooled reactors

International Nuclear Information System (INIS)

Kaneko, Yoshihiko

1996-01-01

Until this century, it is sufficient to aim at the winner of competition in human society to obtain resources, and to entrust waste to natural cleaning action. However, the expansion of social activities has been too fast, and the scale has become too large, consequently, in the next century, the expansion of social activities will be caught by the structure of trilemma that is subjected to the strong restraint and selection from the problems of finite energy and resources and environment preservation. In 21st century, the problems change to those between mankind and nature. Energy supply and population increase, envrionment preservation and human activities, and the matters that human wisdom should bear regarding energy technology are discussed. In Japan, the construction of the high temperature engineering test reactor (HTTR) is in progress. The design of high temperature gas-cooled reactors and their features on the safety are explained. The capability of reducing CO 2 release of high temperature gas-cooled reactors is reported. In future, it is expected that the time of introducing high temperature gas-cooled reactors will come. (K.I.)

Energy efficient residential house wall system

International Nuclear Information System (INIS)

Aldawi, Fayez; Date, Abhijit; Alam, Firoz; Khan, Iftekhar; Alghamdi, Mohammed

2013-01-01

The energy consumption and greenhouse gas emission by the residential housing sector are considered to be one of the largest in economically developed countries. The larger energy consumption and greenhouse gas emission not only put additional pressure on finite fossil fuel resources but also cause global warming and climate change. Additionally, the residential housing sector will be consuming more energy as the house demand and average house floor area are progressively increasing. With currently used residential house wall systems, it is hard to reduce energy consumption for ongoing house space heating and cooling. A smart house wall envelope with optimal thermal masses and insulation materials is vital for reducing our increasing energy consumption. The major aim of this study is to investigate thermal performance and energy saving potential of a new house wall system for variable climate conditions. The thermal performance modelling was carried out using commercially developed software AccuRate ® . The findings indicate that a notable energy savings can be accomplished if a smart house wall system is used. -- Highlights: • Smart house wall system. • Thermal performance modelling and star energy rating. • Energy savings and greenhouse gas reduction

Temperature measurement during solidification of thin wall ductile cast iron. Part 2: Numerical simulations

DEFF Research Database (Denmark)

Pedersen, Karl Martin; Tiedje, Niels Skat

2008-01-01

Temperature measurements in castings are carried out with thermocouples (TC’s), which are inserted in the melt. The TC influence solidification of the casting, especially in thin wall castings where the heat content of the melt is small compared to the cooling power of the TC. A numerical analysi...

Transient temperature and stress distributions in the pressure vessel's wall of a nuclear reactor

International Nuclear Information System (INIS)

Silva, G.A. da

1979-01-01

In order to calculate the temperature distribution in a reactor vessel wall which is under the effect of gamma radiation originated in the reactor core, a numerical solution is proposed. This problem may arise from a reactor cooling pump failure .The thermal stresses are also calculated. (Author) [pt

Mechanical Property and Its Comparison of Superalloys for High Temperature Gas Cooled Reactor

International Nuclear Information System (INIS)

Kim, Woo Gon; Kim, D. W.; Ryu, W. S.; Han, C. H.; Yoon, J. H.; Chang, J.

2005-01-01

Since structural materials for high temperature gas cooled reactor are used during long period in nuclear environment up to 1000 .deg. C, it is important to have good properties at elevated temperature such as mechanical properties (tensile, creep, fatigue, creep-fatigue), microstructural stability, interaction between metal and gas, friction and wear, hydrogen and tritium permeation, irradiation behavior, corrosion by impurity in He. Thus, in order to select excellent materials for the high temperature gas cooled reactor, it is necessary to understand the material properties and to gather the data for them. In this report, the items related to material properties which are needed for designing the high temperature gas cooled reactor were presented. Mechanical properties; tensile, creep, and fatigue etc. were investigated for Haynes 230, Hastelloy-X, In 617 and Alloy 800H, which can be used as the major structural components, such as intermediate heat exchanger (IHX), hot duct and piping and internals. Effect of He and irradiation on these structural materials was investigated. Also, mechanical properties; physical properties, tensile properties, creep and creep crack growth rate were compared for them, respectively. These results of this report can be used as important data to select superior materials for high temperature gas reactor

Plasma-wall interactions

International Nuclear Information System (INIS)

Behrisch, Rainer

1978-01-01

The plasma wall interactions for two extreme cases, the 'vacuum model' and the 'cold gas blanket' are outlined. As a first step for understanding the plasma wall interactions the elementary interaction processes at the first wall are identified. These are energetic ion and neutral particle trapping and release, ion and neutral backscattering, ion sputtering, desorption by ions, photons and electrons and evaporation. These processes have only recently been started to be investigated in the parameter range of interest for fusion research. The few measured data and their extrapolation into regions not yet investigated are reviewed

In-situ study of the gas-phase composition and temperature of an intermediate-temperature solid oxide fuel cell anode surface fed by reformate natural gas

Science.gov (United States)

Santoni, F.; Silva Mosqueda, D. M.; Pumiglia, D.; Viceconti, E.; Conti, B.; Boigues Muñoz, C.; Bosio, B.; Ulgiati, S.; McPhail, S. J.

2017-12-01

An innovative experimental setup is used for in-depth and in-operando characterization of solid oxide fuel cell anodic processes. This work focuses on the heterogeneous reactions taking place on a 121 cm2 anode-supported cell (ASC) running with a H2, CH4, CO2, CO and steam gas mixture as a fuel, using an operating temperature of 923 K. The results have been obtained by analyzing the gas composition and temperature profiles along the anode surface in different conditions: open circuit voltage (OCV) and under two different current densities, 165 mA cm-2 and 330 mA cm-2, corresponding to 27% and 54% of fuel utilization, respectively. The gas composition and temperature analysis results are consistent, allowing to monitor the evolution of the principal chemical and electrochemical reactions along the anode surface. A possible competition between CO2 and H2O in methane internal reforming is shown under OCV condition and low current density values, leading to two different types of methane reforming: Steam Reforming and Dry Reforming. Under a current load of 40 A, the dominance of exothermic reactions leads to a more marked increase of temperature in the portion of the cell close to the inlet revealing that current density is not uniform along the anode surface.

Temperature Evolution of a 1 MA Triple-Nozzle Gas-Puff Z-Pinch

Science.gov (United States)

de Grouchy, Philip; Banasek, Jacob; Engelbrecht, Joey; Qi, Niansheng; Atoyan, Levon; Byvank, Tom; Cahill, Adam; Moore, Hannah; Potter, William; Ransohoff, Lauren; Hammer, David; Kusse, Bruce; Laboratory of Plasma Studies Team

2015-11-01

Mitigation of the Rayleigh-Taylor instability (RTI) plays a critical role in optimizing x-ray output at high-energy ~ 13 keV using the triple-nozzle Krypton gas-puff at Sandia National Laboratory. RTI mitigation by gas-puff density profiling using a triple-nozzle gas-puff valve has recently been recently demonstrated on the COBRA 1MA z-pinch at Cornell University. In support of this work we investigate the role of shell cooling in the growth of RTI during gas-puff implosions. Temperature measurements within the imploding plasma shell are recorded using a 527 nm, 10 GW Thomson scattering diagnostic for Neon, Argon and Krypton puffs. The mass-density profile is held constant at 22 microgram per centimeter for all three puffs and the temperature evolution of the imploding material is recorded. In the case of Argon puffs we find that the shell ion and electron effective temperatures remain in equilibrium at around 1keV for the majority of the implosion phase. In contrast scattered spectra from Krypton are dominated by of order 10 keV effective ion temperatures. Supported by the NNSA Stewardship Sciences Academic Programs.

LiWall Fusion - The New Concept of Magnetic Fusion

International Nuclear Information System (INIS)

Zakharov, L.E.

2011-01-01

Utilization of the outstanding abilities of a liquid lithium layer in pumping hydrogen isotopes leads to a new approach to magnetic fusion, called the LiWall Fusion. It relies on innovative plasma regimes with low edge density and high temperature. The approach combines fueling the plasma by neutral injection beams with the best possible elimination of outside neutral gas sources, which cools down the plasma edge. Prevention of cooling the plasma edge suppresses the dominant, temperature gradient related turbulence in the core. Such an approach is much more suitable for controlled fusion than the present practice, relying on high heating power for compensating essentially unlimited turbulent energy losses.

Coal fly ash utilization: Low temperature sintering of wall tiles

International Nuclear Information System (INIS)

Chandra, Navin; Sharma, Priya; Pashkov, G.L.; Voskresenskaya, E.N.; Amritphale, S.S.; Baghel, Narendra S.

2008-01-01

We present here a study of the sintering of fly ash and its mixture with low alkali pyrophyllite in the presence of sodium hexa meta phosphate (SHMP), a complex activator of sintering, for the purpose of wall tile manufacturing. The sintering of fly ash with SHMP in the temperature range 925-1050 deg. C produces tiles with low impact strength; however, the incremental addition of low alkali pyrophyllite improves impact strength. The impact strength of composites with ≥40% (w/w) pyrophyllite in the fly ash-pyrophyllite mix satisfies the acceptable limit (19.6 J/m) set by the Indian Standards Institute for wall tiles. Increasing the pyrophyllite content results in an increase in the apparent density of tiles, while shrinkage and water absorption decrease. The strength of fly ash tiles is attributed to the formation of a silicophosphate phase; in pyrophyllite rich tiles, it is attributed to the formation of a tridymite-structured T-AlPO 4 phase. Scanning electron micrographs show that the reinforcing rod shaped T-AlPO 4 crystals become more prominent as the pyrophyllite content increases in the sintered tiles

Analysis of condensation on a horizontal cylinder with unknown wall temperature and comparison with the Nusselt model of film condensation

Science.gov (United States)

Bahrami, Parviz A.

1996-01-01

Theoretical analysis and numerical computations are performed to set forth a new model of film condensation on a horizontal cylinder. The model is more general than the well-known Nusselt model of film condensation and is designed to encompass all essential features of the Nusselt model. It is shown that a single parameter, constructed explicitly and without specification of the cylinder wall temperature, determines the degree of departure from the Nusselt model, which assumes a known and uniform wall temperature. It is also known that the Nusselt model is reached for very small, as well as very large, values of this parameter. In both limiting cases the cylinder wall temperature assumes a uniform distribution and the Nusselt model is approached. The maximum deviations between the two models is rather small for cases which are representative of cylinder dimensions, materials and conditions encountered in practice.

Heat transfer and thermodynamic performance of convective–radiative cooling double layer walls with temperature-dependent thermal conductivity and internal heat generation

International Nuclear Information System (INIS)

Torabi, Mohsen; Zhang, Kaili

2015-01-01

Highlights: • First and second laws of thermodynamics have been investigated in a composite wall. • Convective–radiative heat transfer is assumed on both surfaces. • Optimum interface location is calculated to minimize the total entropy generation rate. • Thermal conductivities ratio has great effects on the temperature and entropy generation. - Abstract: Composite geometries have numerous applications in industry and scientific researches. This work investigates the temperature distribution, and local and total entropy generation rates within two-layer composite walls using conjugate convection and radiation boundary conditions. Thermal conductivities of the materials of walls are assumed temperature-dependent. Temperature-dependent internal heat generations are also incorporated into the modeling. The differential transformation method (DTM) is used as an analytical technique to tackle the highly nonlinear system of ordinary differential equations. Thereafter, the local and total entropy generation rates are calculated using the DTM formulated temperature distribution. An exact analytical solution, for the temperature-independent model without radiation effect, is also derived. The correctness and accuracy of the DTM solution are checked against the exact solution. After verification, effects of thermophysical parameters such as location of the interface, convection–conduction parameters, radiation–conduction parameters, and internal heat generations, on the temperature distribution, and both local and total entropy generation rates are examined. To deliver the minimum total entropy generation rate, optimum values for some parameters are also found. Since composite walls are widely used in many fields, the abovementioned investigation is a beneficial tool for many engineering industries and scientific fields to minimize the entropy generation, which is the exergy destruction, of the system

Calculation of gas temperature at the outlet of the combustion chamber and in the air-gas channel of a gas-turbine unit by data of acceptance tests in accordance with ISO

Science.gov (United States)

Kostyuk, A. G.; Karpunin, A. P.

2016-01-01

This article describes a high accuracy method enabling performance of the calculation of real values of the initial temperature of a gas turbine unit (GTU), i.e., the gas temperature at the outlet of the combustion chamber, in a situation where manufacturers do not disclose this information. The features of the definition of the initial temperature of the GTU according to ISO standards were analyzed. It is noted that the true temperatures for high-temperature GTUs is significantly higher than values determined according to ISO standards. A computational procedure for the determination of gas temperatures in the air-gas channel of the gas turbine and cooling air consumptions over blade rims is proposed. As starting equations, the heat balance equation and the flow mixing equation for the combustion chamber are assumed. Results of acceptance GTU tests according to ISO standards and statistical dependencies of required cooling air consumptions on the gas temperature and the blade metal are also used for calculations. An example of the calculation is given for one of the units. Using a developed computer program, the temperatures in the air-gas channel of certain GTUs are calculated, taking into account their design features. These calculations are performed on the previously published procedure for the detailed calculation of the cooled gas turbine subject to additional losses arising because of the presence of the cooling system. The accuracy of calculations by the computer program is confirmed by conducting verification calculations for the GTU of the Mitsubishi Comp. and comparing results with published data of the company. Calculation data for temperatures were compared with the experimental data and the characteristics of the GTU, and the error of the proposed method is estimated.

Forced convection heat transfer in rectangular ducts - general case of wall resistances and peripheral conduction for ventilation cooling of nuclear waste repositories [ heat transfer and nuclear disposal

Energy Technology Data Exchange (ETDEWEB)

Lyczkowski, R. W.; Solbrig, C. W.; Gidaspow, D.

1980-01-01

A numerical solution for laminar flow heat transfer between a flowing gas and its containing rectangular duct has been obtained for many different boundary conditions which may arise in nuclear waste repository ventilation corridors. The problem has been solved for the cases of insulation on no walls, one wall, two walls, and three walls with various finite resistances on the remaining walls. Simplifications are made to decouple the convective heat transfer problem for the far field conduction problem, but peripheral conduction is retained. Results have been obtained for several duct aspect ratios in the thermal entrance and in the fully developed regions, including the constant temperature cases. When one wall is insulated and the other three are at constant temperature, the maximum temperature occurs in the fluid rather than on the insulated wall. This maximum moves toward the insulated wall with increasing axial distance. Nusselt numbers for the same constant flux on all four walls with peripheral conduction lie in a narrow band bounded by zero and infinite peripheral conduction cases. A dimensionless wall conduction group of four can be considered infinite for the purpose of estimating fully developed Nusselt numbers to within an accuracy of 3%. A decrease in wall and bulk temperatures by finite wall conduction has been demonstrated for the case of a black body radiation boundary condition. Nusselt numbers for the case of constant temperature on the top and bottom walls and constant heat flux on the side walls exhibited unexpected behavior.

Effect of pairwise additivity on finite-temperature behavior of classical ideal gas

Science.gov (United States)

Shekaari, Ashkan; Jafari, Mahmoud

2018-05-01

Finite-temperature molecular dynamics simulations have been applied to inquire into the effect of pairwise additivity on the behavior of classical ideal gas within the temperature range of T = 250-4000 K via applying a variety of pair potentials and then examining the temperature dependence of a number of thermodynamical properties. Examining the compressibility factor reveals the most deviation from ideal-gas behavior for the Lennard-Jones system mainly due to the presence of both the attractive and repulsive terms. The systems with either attractive or repulsive intermolecular potentials are found to present no resemblance to real gases, but the most similarity to the ideal one as temperature rises.

Gas anti-solvent precipitation assisted salt leaching for generation of micro- and nano-porous wall in bio-polymeric 3D scaffolds

Energy Technology Data Exchange (ETDEWEB)

Flaibani, Marina; Elvassore, Nicola, E-mail: nicola.elvassore@unipd.it

2012-08-01

The mass transport through biocompatible and biodegradable polymeric 3D porous scaffolds may be depleted by non-porous impermeable internal walls. As consequence the concentration of metabolites and growth factors within the scaffold may be heterogeneous leading to different cell fate depending on spatial cell location, and in some cases it may compromise cell survival. In this work, we fabricated polymeric scaffolds with micro- and nano-scale porosity by developing a new technique that couples two conventional scaffold production methods: solvent casting-salt leaching and gas antisolvent precipitation. 10-15 w/w solutions of a hyaluronic benzyl esters (HYAFF11) and poly-(lactic acid) (PLA) were used to fill packed beds of 0.177-0.425 mm NaCl crystals. The polymer precipitation in micro and nano-porous structures between the salt crystals was induced by high-pressure gas, then its flushing extracted the residual solvent. The salt was removed by water-wash. Morphological analysis by scanning electron microscopy showed a uniform porosity ({approx} 70%) and a high interconnectivity between porous. The polymeric walls were porous themselves counting for 30% of the total porosity. This wall porosity did not lead to a remarkable change in compressive modulus, deformation, and rupture pressure. Scaffold biocompatibility was tested with murine muscle cell line C2C12 for 4 and 7 days. Viability analysis and histology showed that micro- and nano-porous scaffolds are biocompatible and suitable for 3D cell culture promoting cell adhesion on the polymeric wall and allowing their proliferation in layers. Micro- and nano-scale porosities enhance cell migration and growth in the inner part of the scaffold. - Highlights: Black-Right-Pointing-Pointer Gas anti-solvent precipitation and salt leaching for scaffold fabrication. Black-Right-Pointing-Pointer Hyaluronic benzyl esters (HYAFF11) and poly-(lactic acid) (PLA) sponges. Black-Right-Pointing-Pointer Gas anti-solvent precipitation

Gas anti-solvent precipitation assisted salt leaching for generation of micro- and nano-porous wall in bio-polymeric 3D scaffolds

International Nuclear Information System (INIS)

Flaibani, Marina; Elvassore, Nicola

2012-01-01

The mass transport through biocompatible and biodegradable polymeric 3D porous scaffolds may be depleted by non-porous impermeable internal walls. As consequence the concentration of metabolites and growth factors within the scaffold may be heterogeneous leading to different cell fate depending on spatial cell location, and in some cases it may compromise cell survival. In this work, we fabricated polymeric scaffolds with micro- and nano-scale porosity by developing a new technique that couples two conventional scaffold production methods: solvent casting-salt leaching and gas antisolvent precipitation. 10–15 w/w solutions of a hyaluronic benzyl esters (HYAFF11) and poly-(lactic acid) (PLA) were used to fill packed beds of 0.177–0.425 mm NaCl crystals. The polymer precipitation in micro and nano-porous structures between the salt crystals was induced by high-pressure gas, then its flushing extracted the residual solvent. The salt was removed by water-wash. Morphological analysis by scanning electron microscopy showed a uniform porosity (∼ 70%) and a high interconnectivity between porous. The polymeric walls were porous themselves counting for 30% of the total porosity. This wall porosity did not lead to a remarkable change in compressive modulus, deformation, and rupture pressure. Scaffold biocompatibility was tested with murine muscle cell line C2C12 for 4 and 7 days. Viability analysis and histology showed that micro- and nano-porous scaffolds are biocompatible and suitable for 3D cell culture promoting cell adhesion on the polymeric wall and allowing their proliferation in layers. Micro- and nano-scale porosities enhance cell migration and growth in the inner part of the scaffold. - Highlights: ► Gas anti-solvent precipitation and salt leaching for scaffold fabrication. ► Hyaluronic benzyl esters (HYAFF11) and poly-(lactic acid) (PLA) sponges. ► Gas anti-solvent precipitation induces nano-porous structures. ► Scaffolds are biocompatible and

High temperature and high pressure gas cell for quantitative spectroscopic measurements

International Nuclear Information System (INIS)

Christiansen, Caspar; Stolberg-Rohr, Thomine; Fateev, Alexander; Clausen, Sønnik

2016-01-01

A high temperature and high pressure gas cell (HTPGC) has been manufactured for quantitative spectroscopic measurements in the pressure range 1–200 bar and temperature range 300–1300 K. In the present work the cell was employed at up to 100 bar and 1000 K, and measured absorption coefficients of a CO_2–N_2 mixture at 100 bar and 1000 K are revealed for the first time, exceeding the high temperature and pressure combinations previously reported. This paper discusses the design considerations involved in the construction of the cell and presents validation measurements compared against simulated spectra, as well as published experimental data. - Highlights: • A ceramic gas cell designed for gas measurements up to 1300 K and 200 bar. • The first recorded absorption spectrum of CO_2 at 1000 K and 101 bar is presented. • Voigt profiles might suffice in the modeling of radiation from CO_2 in combustion.

Mean free path of nucleons in a Fermi gas at finite temperature

International Nuclear Information System (INIS)

Collins, M.T.; Griffin, J.J.

1980-01-01

The mean free path of a nucleon in a nuclear Fermi gas at finite temperature is calculated by utilizing the free nucleon-nucleon cross section modified to suppress final states excluded by the Pauli principle. The results agree with an earlier zero-temperature calculation but yield substantially smaller values than a previous finite-temperature analysis. The Fermi gas mean free paths are some two to four times shorter than those implied by phenomenological imaginary optical potentials, suggesting that the present Fermi gas model fails to adequately describe the physical processes determining the mean free path. Even so, the present results, taken as lower bounds on te mean free path, require temperatures of some 4.5 MeV before the mean free path of bound nucleons becomes as short as the nuclear diameter. It follows that very high excitation energies are prerequisite to any short mean free path assumption in nuclear heavy-ion collisions. (orig.)

Carbon capture from natural gas using multi-walled CNTs based mixed matrix membranes.

Science.gov (United States)

Hussain, Abid; Farrukh, Sarah; Hussain, Arshad; Ayoub, Muhammad

2017-12-05

Most of the polymers and their blends, utilized in carbon capture membranes, are costly, but cellulose acetate (CA) being inexpensive is a lucrative choice. In this research, pure and mixed matrix membranes (MMMs) have been fabricated to capture carbon from natural gas. Polyethylene glycol (PEG) has been utilized in the fabrication of membranes to modify the chain flexibility of polymers. Multi-walled carbon nanotubes (MWCNTs) provide mechanical strength, thermal stability, an extra free path for CO 2 molecules and augment CO 2 /CH 4 selectivity. Membranes of pure CA, CA/PEG blend of different PEG concentrations (5%, 10%, 15%) and CA/PEG/MWCNTs blend of 10% PEG with different MWCNTs concentrations (5%, 10%, 15%) were prepared in acetone using solution casting techniques. Fabricated membranes were characterized using SEM, TGA and tensile testing. Permeation results revealed remarkable improvement in CO 2 /CH 4 selectivity. In single gas experiments, CO 2 /CH 4 selectivity is enhanced 8 times for pure membranes containing 10% PEG and 14 times for MMMs containing 10% MWCNTs. In mix gas experiments, the CO 2 /CH 4 selectivity is increased 13 times for 10% PEG and 18 times for MMMs with 10% MWCNTs. Fabricated MMMs have a tensile strength of 13 MPa and are more thermally stable than CA membranes.

Effective enhancement of gas separation performance in mixed matrix membranes using core/shell structured multi-walled carbon nanotube/graphene oxide nanoribbons

Science.gov (United States)

Xue, Qingzhong; Pan, Xinglong; Li, Xiaofang; Zhang, Jianqiang; Guo, Qikai

2017-02-01

Novel core/shell structured multi-walled carbon nanotube/graphene oxide nanoribbons (MWCNT@GONRs) nanohybrids were successfully prepared using a modified chemical longitudinal unzipping method. Subsequently, the MWCNT@GONRs nanohybrids were used as fillers to enhance the gas separation performance of polyimide based mixed matrix membranes (MMMs). It is found that MMMs concurrently exhibited higher gas selectivity and higher gas permeability compared to pristine polyimide. The high gas selectivity could be attributed to the GONRs shell, which provided a selective barrier and large gas adsorbed area, while the high gas permeability resulted from the hollow structured MWCNTs core with smooth internal surface, which acted as a rapid transport channel. MWCNT@GONRs could be promising candidates to improve gas separation performance of MMMs due to the unique microstructures, ease of synthesis and low filling loading.

Influence of in-plane field on vertical Bloch line in the walls of the second kind of dumbbell domains at various temperatures

International Nuclear Information System (INIS)

Xu, J.P.; Liu, S.P.; Guo, G.X.; Zhen, C.M.; Tang, G.D.; Sun, H.Y.; Nie, X.F.

2004-01-01

The stability of vertical Bloch lines (VBLs) in the second kind of dumbbell domain (IIDs) walls in liquid phase epitaxy garnet bubble films subjected to an in-plane field at various temperatures is studied experimentally. It is found that there exists a critical in-plane field range depending on temperature, in which vertical Bloch lines (VBLs) in the second kind of IIDs walls are unstable, i.e., [Hip(1)(T),Hip(2)(T)]. Here, Hip(1)(T) is the initial critical in-plane field at which VBLs in the walls of IIDs annihilate; while Hip(2)(T) is the lowest in-plane field at which all VBLs in the walls of IIDs have annihilated completely. Also, the critical in-plane field range [Hip(1)(T),Hip(2)(T)],Hip(1)(T) and Hip(2)(T) all decrease with the temperature increasing. Hip(1)(T) and Hip(2)(T) reach zero at T0' and T0, respectively

Temperature dependence of gas sensing behaviour of TiO2 doped PANI composite thin films

Science.gov (United States)

Srivastava, Subodh; Sharma, S. S.; Sharma, Preetam; Sharma, Vinay; Rajura, Rajveer Singh; Singh, M.; Vijay, Y. K.

2014-04-01

In the present work we have reported the effect of temperature on the gas sensing properties of TiO2 doped PANI composite thin film based chemiresistor type gas sensors for hydrogen gas sensing application. PANI and TiO2 doped PANI composite were synthesized by in situ chemical oxidative polymerization of aniline at low temperature. The electrical properties of these composite thin films were characterized by I-V measurements as function of temperature. The I-V measurement revealed that conductivity of composite thin films increased as the temperature increased. The changes in resistance of the composite thin film sensor were utilized for detection of hydrogen gas. It was observed that at room temperature TiO2 doped PANI composite sensor shows higher response value and showed unstable behavior as the temperature increased. The surface morphology of these composite thin films has also been characterized by scanning electron microscopy (SEM) measurement.

Effect of Temperature Shock and Inventory Surprises on Natural Gas and Heating Oil Futures Returns

Science.gov (United States)

Hu, John Wei-Shan; Lin, Chien-Yu

2014-01-01

The aim of this paper is to examine the impact of temperature shock on both near-month and far-month natural gas and heating oil futures returns by extending the weather and storage models of the previous study. Several notable findings from the empirical studies are presented. First, the expected temperature shock significantly and positively affects both the near-month and far-month natural gas and heating oil futures returns. Next, significant temperature shock has effect on both the conditional mean and volatility of natural gas and heating oil prices. The results indicate that expected inventory surprises significantly and negatively affects the far-month natural gas futures returns. Moreover, volatility of natural gas futures returns is higher on Thursdays and that of near-month heating oil futures returns is higher on Wednesdays than other days. Finally, it is found that storage announcement for natural gas significantly affects near-month and far-month natural gas futures returns. Furthermore, both natural gas and heating oil futures returns are affected more by the weighted average temperature reported by multiple weather reporting stations than that reported by a single weather reporting station. PMID:25133233

Spatiotemporal study of gas heating mechanisms in a radio-frequency electrothermal plasma micro-thruster

Directory of Open Access Journals (Sweden)

Amelia eGreig

2015-10-01

Full Text Available A spatiotemporal study of neutral gas temperature during the first 100 s of operation for a radio-frequency electrothermal plasma micro-thruster operating on nitrogen at 60 W and 1.5 Torr is performed to identify the heating mechanisms involved. Neutral gas temperature is estimated from rovibrational band fitting of the nitrogen second positive system. A set of baffles are used to restrict the optical image and separate the heating mechanisms occurring in the central bulk discharge region and near the thruster walls.For each spatial region there are three distinct gas heating mechanisms being fast heating from ion-neutral collisions with timescales of tens of milliseconds, intermediate heating with timescales of 10 s from ion bombardment on the inner thruster tube surface creating wall heating, and slow heating with timescales of 100 s from gradual warming of the entire thruster housing. The results are discussed in relation to optimising the thermal properties of future thruster designs.

Characterisation of the interaction between liquid film and flue gas flow at walls and internals in FGD scrubbers; Beschreibung der gegenseitigen Beeinflussung von Fluessigkeitsschicht und Rauchgasstroemung an Waenden und internen Einbauten in REA-Waeschern

Energy Technology Data Exchange (ETDEWEB)

Arnold, Mario [Technische Univ. Dortmund (Germany). Lehrstuhl Mechanische Verfahrenstechnik; Fahlenkamp, Hans

2012-07-01

The VGB Research Project 'Characterisation of the interaction between liquid film and flue gas flow at walls and internals in FGD scrubbers' covers the droplet wall interaction in flue gas scrubbers. In the context of optimised FGD design, especially in fulfilling the increasing requirements on the conventional flue gas treatment by the CCS design, a better understanding of the flow behaviour near the wall is crucial. Within the framework of the research project an experimental setup is designed, built up and run. (orig.)

Precise measurements of neutral gas temperature using Fiber Bragg Grating sensor in Argon capacitively coupled plasmas

Science.gov (United States)

Han, Daoman; Liu, Zigeng; Liu, Yongxin; Peng, Wei; Wang, Younian

2016-09-01

Neutral gas temperature was measured using Fiber Bragg Grating sensor (FBGs) in capacitively coupled argon plasmas. Thermometry is based on the thermal equilibrium between the sensor and neutral gases, which is found to become faster with increasing pressure. It is also observed that the neutral gas temperature is higher than the room temperature by 10 120 °depending on the experiental conditions, and gas temperature shows significant non-uniformity in space. In addition, radial profiles of neutral temperature at different pressures, resemble these of ion density, obtained by a floating double probe. Specifically, at low pressure, neutral gas temperature and ion density peak at the center of the reactor, while the peak appears at the edge of the electrode at higher pressure. The neutral gas heating is mainly caused by the elastic collisions of Ar + with neutral gas atoms in the sheath region after Ar + gaining a certain energy. This work was supported by the National Natural Science Foundation of China (NSFC) (Grants No. 11335004, 11405018, and 61137005).

A High-Sensitivity Gas Sensor Toward Methanol Using ZnO Microrods: Effect of Operating Temperature

Science.gov (United States)

Sinha, M.; Mahapatra, R.; Mondal, B.; Ghosh, R.

2017-04-01

In the present work, zinc oxide (ZnO) microrods with the average diameter of 350 nm have been synthesized on fluorine doped tin oxide (FTO) substrate using a hydrothermal reaction process at a low temperature of 90°C. The methanol gas sensing behaviour of as-synthesized ZnO microrods have been studied at different operating temperatures (100-300°C). The gas sensing results show that the ZnO microrods exhibit excellent sensitivity, selectivity, and stability toward methanol gas at 300°C. The as-grown ZnO microrods sensor also shows the good sensitivity for methanol even at a low operating temperature of 100°C. The ultra-high sensitivity of 4.41 × 104% [gas sensitivity, S g = ( I g - I a)/ I a × 100%] and 5.11 × 102% to 100 ppm methanol gas at a temperature of 300°C and 100°C, respectively, has been observed. A fast response time of 200 ms and 270 ms as well as a recovery time of 120 ms and 1330 ms to methanol gas have also been found at an operating temperature of 300°C and 100°C, respectively. The response and recovery time decreases with increasing operation temperature of the sensor.

A design method to isothermalize the core of high-temperature gas-cooled reactors

International Nuclear Information System (INIS)

Takano, M.; Sawa, K.

1987-01-01

A practical design method is developed to isothermalize the core of block-type high-temperature gas-cooled reactors (HTGRs). Isothermalization plays an important role in increasing the design margin on fuel temperature. In this method, the fuel enrichment and the size and boron content of the burnable poison rod are determined over the core blockwise so that the axially exponential and radially flat power distribution are kept from the beginning to the end of core life. The method enables conventional HTGRs to raise the outlet gas temperature without increasing the maximum fuel temperature

Temperature impact on SO2 removal efficiency by ammonia gas scrubbing

International Nuclear Information System (INIS)

He Boshu; Zheng Xianyu; Wen Yan; Tong Huiling; Chen Meiqian; Chen Changhe

2003-01-01

Emissions reduction in industrial processes, i.e. clean production, is an essential requirement for sustainable development. Fossil fuel combustion is the main emission source for gas pollutants, such as NO X , SO 2 and CO 2 , and coal is now a primary energy source used worldwide with coal combustion being the greatest atmospheric pollution source in China. This paper analyzes flue gas cleaning by ammonia scrubbing (FGCAS) for power plants to remove gaseous pollutants, such as NO X , SO 2 and CO 2 , and presents the conceptual zero emission design for power plants. The byproducts from the FGCAS process can be used in agriculture or for gas recovery. Experimental results presented for SO 2 removal from the simulated flue gas in a continuous flow experiment, which was similar to an actual flue gas system, showed that the effectiveness of the ammonia injection or scrubbing depends on the temperature. The FGCAS process can effectively remove SO 2 , but the process temperature should be below 60 deg. C or above 80 deg. C for SO 2 reduction by NH 3 scrubbing

Identification of microscopic domain wall motion from temperature dependence of nonlinear dielectric response.

Czech Academy of Sciences Publication Activity Database

Mokrý, Pavel; Sluka, T.

2017-01-01

Roč. 110, č. 16 (2017), č. článku 162906. ISSN 0003-6951 R&D Projects: GA ČR(CZ) GA14-32228S Institutional support: RVO:61389021 Keywords : microscopic domain wall * electric fields * temperature dependence Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering OBOR OECD: Electrical and electronic engineering Impact factor: 3.411, year: 2016 http://dx.doi.org/10.1063/1.4981874

Analytical study of solids-gas two phase flow

International Nuclear Information System (INIS)

Hosaka, Minoru

1977-01-01

Fundamental studies were made on the hydrodynamics of solids-gas two-phase suspension flow, in which very small solid particles are mixed in a gas flow to enhance the heat transfer characteristics of gas cooled high temperature reactors. Especially, the pressure drop due to friction and the density distribution of solid particles are theoretically analyzed. The friction pressure drop of two-phase flow was analyzed based on the analytical result of the single-phase friction pressure drop. The calculated values of solid/gas friction factor as a function of solid/gas mass loading are compared with experimental results. Comparisons are made for Various combinations of Reynolds number and particle size. As for the particle density distribution, some factors affecting the non-uniformity of distribution were considered. The minimum of energy dispersion was obtained with the variational principle. The suspension density of particles was obtained as a function of relative distance from wall and was compared with experimental results. It is concluded that the distribution is much affected by the particle size and that the smaller particles are apt to gather near the wall. (Aoki, K.)

Anisotropic ordering in a two-temperature lattice gas

DEFF Research Database (Denmark)

Szolnoki, Attila; Szabó, György; Mouritsen, Ole G.

1997-01-01

We consider a two-dimensional lattice gas model with repulsive nearest- and next-nearest-neighbor interactions that evolves in time according to anisotropic Kawasaki dynamics. The hopping of particles along the principal directions is governed by two heat baths at different temperatures T-x and T...

The Validity of 21 cm Spin Temperature as a Kinetic Temperature Indicator in Atomic and Molecular Gas

Energy Technology Data Exchange (ETDEWEB)

Shaw, Gargi [Dept. of Physics, UM-DAE Centre for Excellence in Basic Sciences, University of Mumbai, Mumbai 400098 (India); Ferland, G. J. [Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506 (United States); Hubeny, I., E-mail: gargishaw@gmail.com, E-mail: gary@uky.edu, E-mail: hubeny@as.arizona.edu [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States)

2017-07-10

The gas kinetic temperature ( T {sub K} ) of various interstellar environments is often inferred from observations that can deduce level populations of atoms, ions, or molecules using spectral line observations; H i 21 cm is perhaps the most widely used, and has a long history. Usually the H i 21 cm line is assumed to be in thermal equilibrium and the populations are given by the Boltzmann distribution. A variety of processes, many involving Ly α , can affect the 21 cm line. Here we show how this is treated in the spectral simulation code Cloudy, and present numerical simulations of environments where this temperature indicator is used, with a detailed treatment of the physical processes that determine level populations within H{sup 0}. We discuss situations where this temperature indicator traces T {sub K}, cases where it fails, as well as the effects of Ly α pumping on the 21 cm spin temperature. We also show that the Ly α excitation temperature rarely traces the gas kinetic temperature.

Gas target with thin wall

International Nuclear Information System (INIS)

Korenchenko, A.S.; Korenchenko, S.M.; Kravchuk, N.P.; Filippov, A.I.; Fursov, A.P.

1992-01-01

The technology of targets manufacture with thin wall diameter 100 mm and lengthwise 700 mm from composition kevlar + epoxy resin is described. The test's results on pressure and vacuum are reported. The created targets are supposed to be used on the installation ARES for an investigation of muons and pions interactions with light nuclei and rare pions decay 'on flying'. 5 refs.; 2 figs.; 2 tabs

Plutonium-burn high temperature gas-cooled reactor for 3E+3S

International Nuclear Information System (INIS)

Okamoto, Koji

2015-01-01

The Nuclear Energy Development in Japan is facing a very difficult conditions after Fukushima-Daiichi NPP Accident. Nuclear Energy has strong advantages on 3E, i.e., Energy security, Economical efficiency and Environment. However, people does not believe the Safety 'S' of Nuclear Energy, now. The disadvantage of 'S' overrides the advantages of '3E'. In Nuclear Energy, 'S' is expanded into 3S, i.e., Safety, Security and Safeguards. Especially, the management of Plutonium inventory in Spent Fuel generated by the NPP operation is very important in the viewpoints of non-proliferation. The high-temperature gas cooled reactor (HTGR) is the solution of these disadvantages of '3S' in Nuclear Energy. The fuel of HTGR is composed by 1 mm spherical fuel particle, i.e., TRISO made by fuel, graphite and silicon-carbide. The silicon-carbide can confine the fission products in any conditions of fuel life cycle, i.e., during operation, accidents and disposal for 1 million years. The confinement of the radioactive materials can be confirmed by the TRISO. The HTGR core has strong negative feedback for temperature. So, the fission automatically stopped at the accidental conditions, such as loss of flow and LOCA. Also, the residual heat can be cooled by the radiation heat transfer to reactor vessel wall. The HTGR system usually has passive vessel wall cooling system. When the passive cooling system had been failed, the heat can be transferred to the land by heat conductions, and fuel does not reach the SiC broken temperature. The fission chain reaction has been stopped automatically by negative feedback, i.e., physics. The residual heat had been cooled automatically by radiation. The radioactive materials had been confined automatically by silicon-carbide. The HTGR is superior for 'S' safety. Plutonium can be burned by the HTGR. In the viewpoints of non-proliferation, the fuel should be made by YSZ-PuO 2 , stabilized buffer

Thermal Stress FE Analysis of Large-scale Gas Holder Under Sunshine Temperature Field

Science.gov (United States)

Li, Jingyu; Yang, Ranxia; Wang, Hehui

2018-03-01

The temperature field and thermal stress of Man type gas holder is simulated by using the theory of sunshine temperature field based on ASHRAE clear-sky model and the finite element method. The distribution of surface temperature and thermal stress of gas holder under the given sunshine condition is obtained. The results show that the thermal stress caused by sunshine can be identified as one of the important factors for the failure of local cracked oil leakage which happens on the sunny side before on the shady side. Therefore, it is of great importance to consider the sunshine thermal load in the stress analysis, design and operation of large-scale steel structures such as the gas holder.

Deposition Time and Thermal Cycles of Fabricating Thin-wall Steel Parts by Double Electrode GMAW Based Additive Manufacturing

Directory of Open Access Journals (Sweden)

Yang Dongqing

2017-01-01

Full Text Available The deposition time for fabricating the thin-wall part as well as the peak temperature of the substrate during the process was analyzed in the double electrode gas metal arc welding (DE-GMAW based additive manufacturing (AM. The total deposition time and the interlayer idle time of the manufacturing process decreased with the increasing of the bypass current under the same interlayer temperature and the same deposition rate. The thermal cycling curves illustrated that the peak temperature of the substrate was lower in the DE-GMAW base AM under the same conditions. When depositing the thin-wall parts, the DE-GMAW based AM can reduce the heat input to the substrate and improve the fabrication efficiency, compared with the GMAW based AM.

Experimental Evaluation of Cermet Turbine Stator Blades for Use at Elevated Gas Temperatures

Science.gov (United States)

Chiarito, Patrick T.; Johnston, James R.

1959-01-01

The suitability of cermets for turbine stator blades of a modified turbojet engine was determined at an average turbine-inlet-gas temperature of 2000 F. Such an increase in temperature would yield a premium in thrust from a service engine. Because the cermet blades require no cooling, all the available compressor bleed air could be used to cool a turbine made from conventional ductile alloys. Cermet blades were first run in 100-hour endurance tests at normal gas temperatures in order to evaluate two methods for mounting them. The elevated gas-temperature test was then run using the method of support considered best for high-temperature operation. After 52 hours at 2000 F, one of the group of four cermet blades fractured probably because of end loads resulting from thermal distortion of the spacer band of the nozzle diaphragm. Improved design of a service engine would preclude this cause of premature failure.

Forced convection of liquid hydrogen - Part 2 (continued) - case of large temperature differences between the fluid and the wall (rectangular channel)

International Nuclear Information System (INIS)

Perroud, P.; Rebiere, J.

1965-01-01

Liquid hydrogen flows in a canal of rectangular cross section of 1 x 6 mm ; only one of the larger side is heated (length 190 mm) in order to simulate the cooling of a missile nozzle. The liquid is admitted subcooled at 25 deg. K in average and under a pressure of 8 bars. Mass velocity from 8.9 to 102 g/cm 2 .s, heat flux from 18 to 296.6 W/cm 2 and wall temperature reaching 800 deg. K. Two correlations of local heat transfer coefficients are presented, one for the region in two-phase flow and the other for the region in homogeneous gas-phase which are compared with the formula previously established for a cylindrical canal. An analysis of pressure drop is also given. Gross experimental results are separately published. (authors) [fr

STRUCTURAL SOLUTIONS AND SPECIAL FEATURES OF THE THERMAL PROTECTION ANALYSIS OF EXTERIOR WALLS OF BUILDINGS MADE OF AUTOCLAVED GAS-CONCRETE BLOCKS

Directory of Open Access Journals (Sweden)

Bedov Anatolij Ivanovich

2012-10-01

Full Text Available Relevant structural solutions, physical and mechanical characteristics, coefficients of thermal conductivity for exterior masonry walls made of autoclaved gas-concrete blocks are provided in the article. If a single-layer wall is under consideration, an autoclaved gas-concrete block is capable of performing the two principal functions of a shell structure, including the function of thermal protection and the bearing function. The functions are performed simultaneously. Therefore, the application of the above masonry material means the design development and erection of exterior walls of residential buildings noteworthy for their thermal efficiency. In the event of frameless structures, the height of the residential building in question may be up to 5 stories, while the use of a monolithic or a ready-made frame makes it possible to build high-rise buildings, and the number of stories is not limited in this case. If the average block density is equal to 400…500 kilograms per cubic meter, the designed wall thickness is to be equal to 400 mm. Its thermal resistance may be lower than the one set in the event of the per-element design of the thermal protection (Rreq = 3.41 м2 C/Watt, in Ufa, although it will meet the requirements of the applicable regulations if per-unit power consumption rate is considered.

Corrosion of high temperature alloys in the primary circuit helium of high temperature gas cooled reactors. Pt. 2

International Nuclear Information System (INIS)

Quadakkers, W.J.

1985-01-01

The reactive impurities H 2 O, CO, H 2 and CH 4 which are present in the primary coolant helium of high temperature gas-cooled reactors can cause scale formation, internal oxidation and carburization or decarburization of the high temperature structural alloys. In Part 1 of this contribution a theoretical model was presented, which allows the explanation and prediction of the observed corrosion effects. The model is based on a classical stability diagram for chromium, modified to account for deviations from equilibrium conditions caused by kinetic factors. In this paper it is shown how a stability diagram for a commercial alloy can be constructed and how this can be used to correlate the corrosion results with the main experimental parameters, temperature, gas and alloy composition. Using the theoretical model and the presented experimental results, conditions are derived under which a protective chromia based surface scale will be formed which prevents a rapid transfer of carbon between alloy and gas atmosphere. It is shown that this protective surface oxide can only be formed if the carbon monoxide pressure in the gas exceeds a critical value. Psub(CO), which depends on temperature and alloy composition. Additions of methane only have a limited effect provided that the methane/water ratio is not near to, or greater than, a critical value of around 100/1. The influence of minor alloying additions of strong oxide forming elements, commonly present in high temperature alloys, on the protective properties of the chromia surface scales and the kinetics of carbon transfer is illustrated. (orig.) [de

Global gas balance and influence of atomic hydrogen irradiation on the wall inventory in steady-state operation of QUEST tokamak

Science.gov (United States)

Kuzmin, A.; Zushi, H.; Takagi, I.; Sharma, S. K.; Rusinov, A.; Inoue, Y.; Hirooka, Y.; Zhou, H.; Kobayashi, M.; Sakamoto, M.; Hanada, K.; Yoshida, N.; Nakamura, K.; Fujisawa, A.; Matsuoka, K.; Idei, H.; Nagashima, Y.; Hasegawa, M.; Onchi, T.; Banerjee, S.; Mishra, K.

2015-08-01

Hydrogen wall pumping is studied in steady state tokamak operation (SSTO) of QUEST with all metal plasma facing materials PFMs at 100 °C. The duration of SSTO is up to 820 s in fully non-inductive plasma. Global gas balance analysis shows that wall pumping at the apparent (retention-release) rate of 1-6 × 1018 H/s is dominant and 70-80% of injected H2 can be retained in PFMs. However, immediately after plasma termination the H2 release rate enhances to ∼1019 H/s. In order to understand a true retention process the direct measurement of retention flux has been carried out by permeation probes. The comparison between the evaluated wall retention and results from global analysis is discussed.

Temperature-programmed technique accompanied with high-throughput methodology for rapidly searching the optimal operating temperature of MOX gas sensors.

Science.gov (United States)

Zhang, Guozhu; Xie, Changsheng; Zhang, Shunping; Zhao, Jianwei; Lei, Tao; Zeng, Dawen

2014-09-08

A combinatorial high-throughput temperature-programmed method to obtain the optimal operating temperature (OOT) of gas sensor materials is demonstrated here for the first time. A material library consisting of SnO2, ZnO, WO3, and In2O3 sensor films was fabricated by screen printing. Temperature-dependent conductivity curves were obtained by scanning this gas sensor library from 300 to 700 K in different atmospheres (dry air, formaldehyde, carbon monoxide, nitrogen dioxide, toluene and ammonia), giving the OOT of each sensor formulation as a function of the carrier and analyte gases. A comparative study of the temperature-programmed method and a conventional method showed good agreement in measured OOT.

Low temperature techniques for natural gas purification and LNG production: An energy and exergy analysis

International Nuclear Information System (INIS)

Baccanelli, Margaret; Langé, Stefano; Rocco, Matteo V.; Pellegrini, Laura A.; Colombo, Emanuela

2016-01-01

Highlights: • Low-temperature processes for of high CO_2 content natural gas have been modelled. • Energy and exergy analyses have been performed. • The Dual Pressure distillation scheme has the best thermodynamic performances. • There is a synergy between cryogenic natural gas purification and LNG production. - Abstract: Due to the rapid increase of the World’s primary energy demand of the last decades, low-temperature processes for the purification of natural gas streams with high carbon dioxide content has gained interest, since they allow to make profitable exploitation of low-quality gas reserves. Low temperature purification processes allow the direct production of a methane stream at high purity and at low-temperature, suitable conditions for the direct synergistic integration with natural gas cryogenic liquefaction processes, while CO_2 is obtained in liquid phase and under pressure. In this way, it can be pumped for transportation, avoiding significant compression costs as for classical CO_2 capture units (where carbon dioxide is discharged in gas phase and at atmospheric pressure), and further uses such as Enhanced Oil Recovery (EOR) or underground storage. In this paper, the three most common natural gas low-temperature purification techniques have been modelled and their performances have been evaluated through energy and exergy analyses. Specifically, the dual pressure low-temperature distillation process, the anti-sublimation process and a hybrid configuration have been considered. It is found that the dual pressure low-temperature distillation scheme reach the highest thermodynamic performances, resulting in the best values of exergy efficiency and equivalent methane requirements with respect to the other configurations. This is mainly due to the distributed temperature profile along a distillation column, resulting in a less irreversible heat exchanging process.

The effects of inlet temperature and turbulence characteristics on the flow development inside a gas turbine exhaust diffuser

Science.gov (United States)

Bomela, Christian Loangola

The overall industrial gas turbine efficiency is known to be influenced by the pressure recovery in the exhaust system. The design and, subsequently, the performance of an industrial gas turbine exhaust diffuser largely depend on its inflow conditions dictated by the turbine last stage exit flow state and the restraints of the diffuser internal geometry. Recent advances in Computational Fluid Dynamics (CFD) tools and the availability of computer hardware at an affordable cost made the virtual tool a very attractive one for the analysis of fluid flow through devices like a diffuser. In this backdrop, CFD analyses of a typical industrial gas turbine hybrid exhaust diffuser, consisting of an annular diffuser followed by a conical portion, have been carried out with the purpose of improving the performance of these thermal devices using an open-source CFD code "OpenFOAM". The first phase in the research involved the validation of the CFD approach using OpenFOAM by comparing CFD results against published benchmark experimental data. The numerical results closely captured the flow reversal and the separated boundary layer at the shroud wall where a steep velocity gradient has been observed. The standard k --epsilon turbulence model slightly over-predicted the mean velocity profile in the casing boundary layer while slightly under-predicted it in the reversed flow region. A reliable prediction of flow characteristics in this region is very important as the presence of the annular diffuser inclined wall has the most dominant effect on the downstream flow development. The core flow region and the presence of the hub wall have only a minor influence as reported by earlier experimental studies. Additional simulations were carried out in the second phase to test the veracity of other turbulence models; these include RNG k--epsilon, the SST k--o, and the Spalart-Allmaras turbulence models. It was found that a high resolution case with 47.5 million cells using the SST k

Po2 temperature blood factor for blood gas apparatus.

Science.gov (United States)

Teisseire, B P; Hérigault, R A; Teisseire, L J; Laurent, D N

1984-01-01

PO2 temperature formulae supplied by manufacturers on automatic blood gas apparatus, PO2 corr. = PO2 37 degrees C X 10F X delta T were studied and compared to the experimental determination of the delta log PO2/delta T ratio (Hérigault et al. [10]). Acid-base status at 37 degrees C appeared to have a measurable influence on the PO2 temperature factor; alkalosis increased the delta log PO2/delta T ratio, and the contrary was found for acidosis in comparison with normal acid-base status at 37 degrees C. For the same PO2, measured at 37 degrees C, all the proposed formulae of commercial blood gas automatic apparatus did not give the same temperature corrected PO2. The observed difference between the corrected PO2 may be important and greater than the precision of the initial measurement. To correct the measured PO2 for temperature, a relationship between delta log PO2/delta T and PO2 is proposed, between PO2 zero and PO2 180 mmHg, which takes into account measured pH and PO2 values at 37 degrees C:delta log PO2/delta T = [(-0.35 pH + 0.658) X 10(-4) X PO2] + 0.035.

Over all separation factors for stable isotopes by gas centrifuge

International Nuclear Information System (INIS)

Chuntong Ying; Nie Yuguang; Zeng Shi; Shang Xiuyong; Wood, Houston G.

1999-01-01

The separation factor for the elements with molar wight differences, γ 0 , is an important characteristic parameter for separation of varied isotopes. Besides the dependence on construction parameters of the gas centrifuge it depends on many variables. Some of them are operation conditions, such as feeding flow rate F, pressure at wall p w , temperature T 0 and distribution temperature on the wall and others. Separation factor γ 0 depends on physical properties, such as molar weight M, viscosity μ, product of ρD, where ρ is density of working media and D is its diffusion coefficient. It was taken four examples: UF 6 , WF 6 , OsO 4 and Xe [ru

Stability of test environments for performance evaluation of materials for the modular high-temperature gas-cooled reactor

International Nuclear Information System (INIS)

Edgemon, G.L.; Wilson, D.F.; Bell, G.E.C.

1993-01-01

Stability of the primary helium-based coolant test gas for use in performance ests of materials for the Modular High-Temperature Gas-Cooled Reactor (MHTGR) was determined. Results of tests of the initial gas chemistry from General Atomics (GA) at elevated temperatures, and the associated results predicted by the SOLGASMIX trademark modelling package are presented. Results indicated that for this gas composition and at flow rates obtainable in the test loop, 466 ± 24C is the highest temperature that can be maintained without significantly altering the specified gas chemistry. Four additional gas chemistries were modelled using SOLGASMIX trademark

Investigation of ambient temperature on the performance of GE-F5 gas turbine

International Nuclear Information System (INIS)

Ghazikhani, M.; Taffazoli, D.; Manshori, N.

2002-01-01

The role of ambient temperature in determining the performance of GE-F5 gas turbine is analysed by investigating the Shirvan gas turbine power plant 10 MW , 15 MW and 20 MW power output. These parameters have been brought as a function of ambient temperature. The results show when ambient temperature increases 1 deg C, The compressor pressure decreases about 20 k Pa, compressor outlet temperature increases about 1.13 deg C and exhaust temperature increases about 2.5 deg C. It is revealed that variations are due to decreasing the efficiency of compressor and less due to mass flow rate of air reduction as ambient temperature increases at constant power output. The results shows cycle efficiency reduces 3% with increasing 50 of ambient temperature, also the m increases as ambient temperature increase for constant turbine work. These are also because of reducing the compressor efficiency as ambient temperature increases

Thermodynamic control-oriented modeling of cycle-to-cycle exhaust gas temperature in an HCCI engine

International Nuclear Information System (INIS)

Dehghani Firoozabadi, M.; Shahbakhti, M.; Koch, C.R.; Jazayeri, S.A.

2013-01-01

Highlights: • First thermodynamic model in the literature to predict exhaust temperature in HCCI engines. • The model can be used for integrated control of HCCI combustion and exhaust temperature. • The model is experimentally validated at over 300 steady state and transient conditions. • Results show a good agreement between predicted and measured exhaust temperatures. • Sensitivity of exhaust gas temperature to variation of engine variables is shown. - Abstract: Model-based control of Homogenous Charge Compression Ignition (HCCI) engine exhaust temperature is a viable solution to optimize efficiency of both engine and the exhaust aftertreatment system. Low exhaust temperature in HCCI engines can limit the abatement of hydrocarbon (HC) and carbon monoxide (CO) emissions in an exhaust aftertreatment system. A physical–empirical model is described for control of exhaust temperature in HCCI engines. This model captures cycle-to-cycle dynamics affecting exhaust temperature and is based on thermodynamic relations and semi-empirical correlations. It incorporates intake and exhaust gas flow dynamics, residual gas mixing, and fuel burn rate and is validated with experimental data from a single cylinder engine at over 300 steady state and transient conditions. The validation results indicate a good agreement between predicted and measured exhaust gas temperature

Connection Temperatures during the Mokrsko Fire Test

Directory of Open Access Journals (Sweden)

J. Chlouba

2009-01-01

Full Text Available The Mokrsko fire test focused on the overall behaviour of the structure, which cannot be observed on the separate elements, and also on the temperature of connections with improved fire resistance. During the test, measurements were made of the temperature of the gas and of the elements, the overall and relative deformations, gas pressure, humidity, the radiation of the compartment to structural element and the external steel column, transport of the moisture through the walls, and also the climatic conditions. The results of the test show the differences between the behaviour of the element and the behaviour of the structure exposed to high temperatures during a fire. The collapse of the composite slab was reached. The results of the numerical simulations using the SAFIR program compared well with the measured temperature values in the structure and also in the connections. 

Heat transfer by liquids in suspension in a turbulent gas stream (1960)

International Nuclear Information System (INIS)

Grison, E.; Commissariat a l'Energie Atomique, Saclay

1960-01-01

The introduction of a small volume of liquid into a turbulent gas stream used as cooling agent improves considerably the heat transfer coefficient of the gas. When the turbulent regime is established, one observes in a cylindrical tube two types of flow whether the liquid wets or does not wet the wall. In the first case, one gets on the wall an annular liquid film and droplets in suspension are in the gas stream. In the second case, a fog of droplets is formed without any liquid film on the wall. Experiments were performed with the following mixtures: water-hydrogen, water-nitrogen, ethanol-nitrogen (wetting liquids) introduced into a stainless steel tube of 4 mm ID, electrically heated on 320 mm of length. We varied the gas flow rate (Reynolds until 50000), the rate of the liquid flow rate to gas flow rate (until 15), the pressure (until 10 kg/cm 2 ), the temperature (until the boiling point) and the heat flux (until 250 W/cm 2 ). Two types of burnout were observed. A formula of correlation of the burnout heat flux is given. Making use of the analogy between mass transfer and heat transfer, a dimensionless formula of correlation of the local heat transfer coefficients is established. (author) [fr

Miniaturized Planar Room Temperature Ionic Liquid Electrochemical Gas Sensor for Rapid Multiple Gas Pollutants Monitoring.

Science.gov (United States)

Wan, Hao; Yin, Heyu; Lin, Lu; Zeng, Xiangqun; Mason, Andrew J

2018-02-01

The growing impact of airborne pollutants and explosive gases on human health and occupational safety has escalated the demand of sensors to monitor hazardous gases. This paper presents a new miniaturized planar electrochemical gas sensor for rapid measurement of multiple gaseous hazards. The gas sensor features a porous polytetrafluoroethylene substrate that enables fast gas diffusion and room temperature ionic liquid as the electrolyte. Metal sputtering was utilized for platinum electrodes fabrication to enhance adhesion between the electrodes and the substrate. Together with carefully selected electrochemical methods, the miniaturized gas sensor is capable of measuring multiple gases including oxygen, methane, ozone and sulfur dioxide that are important to human health and safety. Compared to its manually-assembled Clark-cell predecessor, this sensor provides better sensitivity, linearity and repeatability, as validated for oxygen monitoring. With solid performance, fast response and miniaturized size, this sensor is promising for deployment in wearable devices for real-time point-of-exposure gas pollutant monitoring.

The effect of carrier gas flow rate and source cell temperature on low pressure organic vapor phase deposition simulation by direct simulation Monte Carlo method

Science.gov (United States)

Wada, Takao; Ueda, Noriaki

2013-01-01

The process of low pressure organic vapor phase deposition (LP-OVPD) controls the growth of amorphous organic thin films, where the source gases (Alq3 molecule, etc.) are introduced into a hot wall reactor via an injection barrel using an inert carrier gas (N2 molecule). It is possible to control well the following substrate properties such as dopant concentration, deposition rate, and thickness uniformity of the thin film. In this paper, we present LP-OVPD simulation results using direct simulation Monte Carlo-Neutrals (Particle-PLUS neutral module) which is commercial software adopting direct simulation Monte Carlo method. By estimating properly the evaporation rate with experimental vaporization enthalpies, the calculated deposition rates on the substrate agree well with the experimental results that depend on carrier gas flow rate and source cell temperature. PMID:23674843

The effect of carrier gas flow rate and source cell temperature on low pressure organic vapor phase deposition simulation by direct simulation Monte Carlo method

Science.gov (United States)

Wada, Takao; Ueda, Noriaki

2013-04-01

The process of low pressure organic vapor phase deposition (LP-OVPD) controls the growth of amorphous organic thin films, where the source gases (Alq3 molecule, etc.) are introduced into a hot wall reactor via an injection barrel using an inert carrier gas (N2 molecule). It is possible to control well the following substrate properties such as dopant concentration, deposition rate, and thickness uniformity of the thin film. In this paper, we present LP-OVPD simulation results using direct simulation Monte Carlo-Neutrals (Particle-PLUS neutral module) which is commercial software adopting direct simulation Monte Carlo method. By estimating properly the evaporation rate with experimental vaporization enthalpies, the calculated deposition rates on the substrate agree well with the experimental results that depend on carrier gas flow rate and source cell temperature.

Design activity of IHI on the experimental multipurpose high temperature gas-cooled reactor

International Nuclear Information System (INIS)

1978-01-01

With conspicuous interest and attention paid by iron and steel manufacturing industries, the development of the multipurpose high temperature gas-cooled reactor, namely the process heat reactor has been energetically discussed in Japan. The experimental multipurpose high temperature gas-cooled reactor, planned by JAERI (the Japan Atomic Energy Research Institute), is now at the end of the adjustment design stage and about to enter the system synthesizing design stage. The design of the JAERI reactor as a pilot plant for process heat reactors that make possible the direct use of the heat, produced in the reactor, for other industrial uses was started in 1969, and has undergone several revisions up to now. The criticality of the JAERI reactor is expected to be realized before 1985 according to the presently published program. IHI has engaged in the developing work of HTGR (high temperature gas-cooled reactor) including VHTR (very high temperature gas-cooled reactor) for over seven years, producing several achievements. IHI has also participated in the JAERI project since 1973 with some other companies concerned in this field. The design activity of IHI in the development of the JAERI reactor is briefly presented in this paper. (auth.)

Analysis of Heat Transfer and Pressure Drop for a Gas Flowing Through a set of Multiple Parallel Flat Plates at High Temperatures

Science.gov (United States)

Einstein, Thomas H.

1961-01-01

Equations were derived representing heat transfer and pressure drop for a gas flowing in the passages of a heater composed of a series of parallel flat plates. The plates generated heat which was transferred to the flowing gas by convection. The relatively high temperature level of this system necessitated the consideration of heat transfer between the plates by radiation. The equations were solved on an IBM 704 computer, and results were obtained for hydrogen as the working fluid for a series of cases with a gas inlet temperature of 200 R, an exit temperature of 5000 0 R, and exit Mach numbers ranging from 0.2 to O.8. The length of the heater composed of the plates ranged from 2 to 4 feet, and the spacing between the plates was varied from 0.003 to 0.01 foot. Most of the results were for a five- plate heater, but results are also given for nine plates to show the effect of increasing the number of plates. The heat generation was assumed to be identical for each plate but was varied along the length of the plates. The axial variation of power used to obtain the results presented is the so-called "2/3-cosine variation." The boundaries surrounding the set of plates, and parallel to it, were assumed adiabatic, so that all the power generated in the plates went into heating the gas. The results are presented in plots of maximum plate and maximum adiabatic wall temperatures as functions of parameters proportional to f(L/D), for the case of both laminar and turbulent flow. Here f is the Fanning friction factor and (L/D) is the length to equivalent diameter ratio of the passages in the heater. The pressure drop through the heater is presented as a function of these same parameters, the exit Mach number, and the pressure at the exit of the heater.

Numerical simulation of heat fluxes in a two-temperature plasma at shock tube walls

International Nuclear Information System (INIS)

Kuznetsov, E A; Poniaev, S A

2015-01-01

Numerical simulation of a two-temperature three-component Xenon plasma flow is presented. A solver based on the OpenFOAM CFD software package is developed. The heat flux at the shock tube end wall is calculated and compared with experimental data. It is shown that the heat flux due to electrons can be as high as 14% of the total heat flux. (paper)

Numerical simulation of heat fluxes in a two-temperature plasma at shock tube walls

Science.gov (United States)

Kuznetsov, E. A.; Poniaev, S. A.

2015-12-01

Numerical simulation of a two-temperature three-component Xenon plasma flow is presented. A solver based on the OpenFOAM CFD software package is developed. The heat flux at the shock tube end wall is calculated and compared with experimental data. It is shown that the heat flux due to electrons can be as high as 14% of the total heat flux.

Disentangling the role of athermal walls on the Knudsen paradox in molecular and granular gases

Science.gov (United States)

Gupta, Ronak; Alam, Meheboob

2018-01-01

The nature of particle-wall interactions is shown to have a profound impact on the well-known "Knudsen paradox" [or the "Knudsen minimum" effect, which refers to the decrease of the mass-flow rate of a gas with increasing Knudsen number Kn, reaching a minimum at Kn˜O (1 ) and increasing logarithmically with Kn as Kn→∞ ] in the acceleration-driven Poiseuille flow of rarefied gases. The nonmonotonic variation of the flow rate with Kn occurs even in a granular or dissipative gas in contact with thermal walls. The latter result is in contradiction with recent work [Alam et al., J. Fluid Mech. 782, 99 (2015), 10.1017/jfm.2015.523] that revealed the absence of the Knudsen minimum in granular Poiseuille flow for which the flow rate was found to decrease at large values of Kn. The above conundrum is resolved by distinguishing between "thermal" and "athermal" walls, and it is shown that, for both molecular and granular gases, the momentum transfer to athermal walls is much different than that to thermal walls which is directly responsible for the anomalous flow-rate variation with Kn in the rarefied regime. In the continuum limit of Kn→0 , the athermal walls are shown to be closely related to "no-flux" ("adiabatic") walls for which the Knudsen minimum does not exist either. A possible characterization of athermal walls in terms of (1) an effective specularity coefficient for the slip velocity and (2) a flux-type boundary condition for granular temperature is suggested based on simulation results.

On local thermal equilibrium and potential gradient vs current characteristic in wall-stabilized argon plasma arc at 0.1 atm pressure

International Nuclear Information System (INIS)

Shindo, Haruo; Imazu, Shingo; Inaba, Tsuginori.

1979-01-01

In wall-stabilized arc which is a very useful means for determining the transport characteristics of high temperature gases, it is the premise that the inside of arc column is in complete local thermal equilibrium (LTE). In general, the higher the gas pressure, the easier the establishment of LTE, accordingly the experimental investigations on the characteristics of arc discharge as well as the transport characteristics so far were limited to the region of relatively high pressure. However, the authors have found that the theoretical potential vs. current characteristic obtained by the transport characteristic was greatly different from the actually measured one in low pressure region, as the fundamental characteristic of wall-stabilized argon plasma arc below atmospheric pressure. This time, they have clarified this discrepancy at 0.1 atm using the plasma parameters obtained through the spectroscopic measurements. The spectroscopic measurements have been performed through the side observation window at the position 5.5 cm away from the cathode, when arc was ignited vertically at the electrodes distant by 11 cm. Arc radius was 0.5 cm. Electron density and temperature, gas temperature and the excitation density of argon neutral atoms have been experimentally measured. The investigations showed that, in the region of low arc current, where the ratio of current to arc radius is less than 200 A/cm, the fall of gas temperature affected greatly on the decrease of axial electric field of arc column. The non-equilibrium between electron temperature and gas temperature decreased with the increase of arc current, and it was concluded that LTE has been formed at the center portion of arc column above I/R = 300 A/cm. (Wakatsuki, Y.)

Dynamic wall demonstration project

Energy Technology Data Exchange (ETDEWEB)

Nakatsui, L.; Mayhew, W.

1990-12-01

The dynamic wall concept is a ventilation strategy that can be applied to a single family dwelling. With suitable construction, outside air can be admitted through the exterior walls of the house to the interior space to function as ventilation air. The construction and performance monitoring of a demonstration house built to test the dynamic wall concept in Sherwood Park, Alberta, is described. The project had the objectives of demonstrating and assessing the construction methods; determining the cost-effectiveness of the concept in Alberta; analyzing the operation of the dynamic wall system; and determining how other components and systems in the house interact with the dynamic wall. The exterior wall construction consisted of vinyl siding, spun-bonded polyolefin-backed (SBPO) rigid fiberglass sheathing, 38 mm by 89 mm framing, fiberglass batt insulation and 12.7 mm drywall. The mechanical system was designed to operate in the dynamic (negative pressure) mode, however flexibility was provided to allow operation in the static (balanced pressure) mode to permit monitoring of the walls as if they were in a conventional house. The house was monitored by an extensive computerized monitoring system. Dynamic wall operation was dependent on pressure and temperature differentials between indoor and outdoor as well as wind speed and direction. The degree of heat gain was found to be ca 74% of the indoor-outdoor temperature differential. Temperature of incoming dynamic air was significantly affected by solar radiation and measurement of indoor air pollutants found no significant levels. 4 refs., 34 figs., 11 tabs.

Fundamental conceptual design of the experimental multi-purpose high-temperature gas-cooled reactor

International Nuclear Information System (INIS)

Shimokawa, Junichi; Yasuno, Takehiko; Yasukawa, Shigeru; Mitake, Susumu; Miyamoto, Yoshiaki

1975-06-01

The fundamental conceptual design of the experimental multi-purpose very high-temperature gas-cooled reactor (experimental VHTR of thermal output 50 MW with reactor outlet-gas temperature 1,000 0 C) has been carried out to provide the operation modes of the system consisting of the reactor and the heat-utilization system, including characteristics and performance of the components and safety of the plant system. For the heat-utilization system of the plant, heat distribution, temperature condition, cooling system constitution, and the containment facility are specified. For the operation of plant, testing capability of the reactor and controlability of the system are taken into consideration. Detail design is made of the fuel element, reactor core, reactivity control and pressure vessel, and also the heat exchanger, steam reformer, steam generator, helium circulator, helium-gas turbine, and helium-gas purification, fuel handling, and engineered safety systems. Emphasis is placed on providing the increase of the reactor outlet-gas temperature. Fuel element design is directed to the prismatic graphite blocks of hexagonal cross-section accommodating the hollow or tubular fuel pins sheathed in graphite sleeve. The reactor core is composed of 73 fuel columns in 7 stages, concerning the reference design MK-II. Orificing is made in the upper portion of core; one orifice for every 7 fuel columns. Average core power density is 2.5 watts/cm 3 . Fuel temperature is kept below 1,300 0 C in rated power. The main components, i.e. pressure vessel, reformer, gas turbine and intermediate heat exchanger are designed in detail; the IHX is of a double-shell and helically-wound tube coils, the reformer is of a byonet tube type, and the turbine-compressor unit is of an axial flow type (turbine in 6 stages and compressor in 16 stages). (auth.)

[Investigation on the gas temperature of a plasma jet at atmospheric pressure by emission spectrum].

Science.gov (United States)

Li, Xue-chen; Yuan, Ning; Jia, Peng-ying; Niu, Dong-ying

2010-11-01

A plasma jet of a dielectric barrier discharge in coaxial electrode was used to produce plasma plume in atmospheric pressure argon. Spatially and temporally resolved measurement was carried out by photomultiplier tubes. The light emission signals both from the dielectric barrier discharge and from the plasma plume were analyzed. Furthermore, emission spectrum from the plasma plume was collected by high-resolution optical spectrometer. The emission spectra of OH (A 2sigma + --> X2 II, 307.7-308.9 nm) and the first negative band of N2+ (B2 sigma u+ --> X2 IIg+, 390-391.6 nm) were used to estimate the rotational temperature of the plasma plume by fitting the experimental spectra to the simulated spectra. The rotational temperature obtained is about 443 K by fitting the emission spectrum from the OH, and that from the first negative band of N2+ is about 450 K. The rotational temperatures obtained by the two method are consistent within 5% error band. The gas temperature of the plasma plume at atmospheric pressure was obtained because rotational temperature equals to gas temperature approximately in gas discharge at atmospheric pressure. Results show that gas temperature increases with increasing the applied voltage.

THE EFFECT OF THE WINDOW-TO-WALL RATIO ON COOLING ENERGY USAGE AND COMFORT TEMPERATURE

Directory of Open Access Journals (Sweden)

Aris Budhiyanto

2017-12-01

Full Text Available This study presents an investigation of the effect of building envelope, especially glass facade buildings on cooling energy usage and thermal comfort. An office building was modeled with various window-to-wall ratio (WWR using panasap glass with SC=0.58 in order to analyze the effect of the WWR addition on cooling energy usage and comfort temperature. The result suggested that the average increase of the cooling energy usage is about 5.67% per 10% WWR addition, and of the operative temperature ranges from 0.350C to 0.560C per 10% WWR addition. Moreover, the building with above 20% WWR doesn’t provide comfort temperature.

Two methods to measure granular gas temperature

Science.gov (United States)

Chastaing, J.-Y.; Géminard, J.-C.; Naert, A.

2017-07-01

Grains are vibrated so as to achieve a granular gas, here regarded as an archetype of a dissipative non equilibrium steady state (NESS). We report on two distinct and concordant experimental measures of the system effective temperature. To do so, a blade fastened to the shaft of a small DC-motor, immersed in the grains, behaves as a driven 1D Brownian rotator, which is used as both actuator and sensor simultaneously. On the one hand, the Gallavotti-Cohen fluctuation theorem, which involves a measure of the asymmetry of the energy exchanges between the rotator and the NESS reservoir, provides a first effective temperature. On the other hand, the fluctuation-dissipation theorem, which involves the relation between the spontaneous fluctuations and the response to a weak perturbation, defines a second, independent, effective temperature. Both methods, even though they are based on drastically different ideas, give nicely concordant results.

Global gas balance and influence of atomic hydrogen irradiation on the wall inventory in steady-state operation of QUEST tokamak

Energy Technology Data Exchange (ETDEWEB)

Kuzmin, A., E-mail: kuzmin@triam.kyushu-u.ac.jp [RIAM, Kyushu University, 6-1 Kasugakoen, Kasuga, Fukuoka 816-8580 (Japan); Zushi, H. [RIAM, Kyushu University, 6-1 Kasugakoen, Kasuga, Fukuoka 816-8580 (Japan); Takagi, I. [Graduate School of Engineering, Kyoto University (Japan); Sharma, S.K. [Institute for Plasma Research, Ahmadabad, Gujrat (India); Rusinov, A. [RIAM, Kyushu University, 6-1 Kasugakoen, Kasuga, Fukuoka 816-8580 (Japan); Inoue, Y. [IGSES, Kyushu University, 6-1 Kasugakoen, Kasuga, Fukuoka 816-8580 (Japan); Hirooka, Y. [National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292 (Japan); Zhou, H. [Graduate School for Advanced Studies, 322-6 Oroshi, Toki, Gifu 509-5292 (Japan); Kobayashi, M. [National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292 (Japan); Sakamoto, M. [Plasma Research Center, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan); Hanada, K.; Yoshida, N.; Nakamura, K.; Fujisawa, A.; Matsuoka, K.; Idei, H.; Nagashima, Y.; Hasegawa, M.; Onchi, T. [RIAM, Kyushu University, 6-1 Kasugakoen, Kasuga, Fukuoka 816-8580 (Japan); Banerjee, S. [IGSES, Kyushu University, 6-1 Kasugakoen, Kasuga, Fukuoka 816-8580 (Japan); and others

2015-08-15

Hydrogen wall pumping is studied in steady state tokamak operation (SSTO) of QUEST with all metal plasma facing materials PFMs at 100 °C. The duration of SSTO is up to 820 s in fully non-inductive plasma. Global gas balance analysis shows that wall pumping at the apparent (retention–release) rate of 1–6 × 10{sup 18} H/s is dominant and 70–80% of injected H{sub 2} can be retained in PFMs. However, immediately after plasma termination the H{sub 2} release rate enhances to ∼10{sup 19} H/s. In order to understand a true retention process the direct measurement of retention flux has been carried out by permeation probes. The comparison between the evaluated wall retention and results from global analysis is discussed.

Global gas balance and influence of atomic hydrogen irradiation on the wall inventory in steady-state operation of QUEST tokamak

International Nuclear Information System (INIS)

Kuzmin, A.; Zushi, H.; Takagi, I.; Sharma, S.K.; Rusinov, A.; Inoue, Y.; Hirooka, Y.; Zhou, H.; Kobayashi, M.; Sakamoto, M.; Hanada, K.; Yoshida, N.; Nakamura, K.; Fujisawa, A.; Matsuoka, K.; Idei, H.; Nagashima, Y.; Hasegawa, M.; Onchi, T.; Banerjee, S.

2015-01-01

Hydrogen wall pumping is studied in steady state tokamak operation (SSTO) of QUEST with all metal plasma facing materials PFMs at 100 °C. The duration of SSTO is up to 820 s in fully non-inductive plasma. Global gas balance analysis shows that wall pumping at the apparent (retention–release) rate of 1–6 × 10 18 H/s is dominant and 70–80% of injected H 2 can be retained in PFMs. However, immediately after plasma termination the H 2 release rate enhances to ∼10 19 H/s. In order to understand a true retention process the direct measurement of retention flux has been carried out by permeation probes. The comparison between the evaluated wall retention and results from global analysis is discussed

Long wavelength infrared radiation thermometry for non-contact temperature measurements in gas turbines

Science.gov (United States)

Manara, J.; Zipf, M.; Stark, T.; Arduini, M.; Ebert, H.-P.; Tutschke, A.; Hallam, A.; Hanspal, J.; Langley, M.; Hodge, D.; Hartmann, J.

2017-01-01

The objective of the EU project "Sensors Towards Advanced Monitoring and Control of Gas Turbine Engines (acronym STARGATE)" is the development of a suite of advanced sensors, instrumentation and related systems in order to contribute to the developing of the next generation of green and efficient gas turbine engines. One work package of the project deals with the design and development of a long wavelength infrared (LWIR) radiation thermometer for the non-contact measurement of the surface temperature of thermal barrier coatings (TBCs) during the operation of gas turbine engines. For opaque surfaces (e.g. metals or superalloys) radiation thermometers which are sensitive in the near or short wavelength infrared are used as state-of-the-art method for non-contact temperature measurements. But this is not suitable for oxide ceramic based TBCs (e.g. partially yttria stabilized zirconia) as oxide ceramics are semi-transparent in the near and short wavelength infrared spectral region. Fortunately the applied ceramic materials are non-transparent in the long wavelength infrared and additionally exhibit a high emittance in this wavelength region. Therefore, a LWIR pyrometer can be used for non-contact temperature measurements of the surfaces of TBCs as such pyrometers overcome the described limitation of existing techniques. For performing non-contact temperature measurements in gas turbines one has to know the infrared-optical properties of the applied TBCs as well as of the hot combustion gas in order to properly analyse the measurement data. For reaching a low uncertainty on the one hand the emittance of the TBC should be high (>0.9) in order to reduce reflections from the hot surrounding and on the other hand the absorbance of the hot combustion gas should be low (<0.1) in order to decrease the influence of the gas on the measured signal. This paper presents the results of the work performed by the authors with focus on the implementation of the LWIR pyrometer and the

Study of the MWPC gas gain behaviour as a function of the gas pressure and temperature

CERN Document Server

Pinci, D

2005-01-01

The Muon System of the LHCb experiment is composed of five detection stations (M1-M5) equipped with 1368 Multi-Wire Proportional Chambers (MWPC) and 24 Triple-GEM detectors. The Multi Wire Proportional Chamber (MWPC) performances (detection efficiency, time resolution, pad-cluster size and ageing properties) are heavily dependent on the gas gain. The chamber gain depends on the gas density and therefore on the gas temperature and pressure. The impact of the environmental parameters on the MWPC gain has been studied in detail. The results, togheter with a simple method proposed to account for the gain variations, are reported in this note. The absolute gas gain at the testing voltage of 2750 V was also measured to be (1.2 +- 0.1)*10^5.

Ambient temperature effects on gas turbine power plant: A case study in Iran

International Nuclear Information System (INIS)

Gorji, M.; Fouladi, F.

2007-01-01

Actual thermal efficiency, electric-power output, fuel-air ratio and specific fuel consumption (SFC) vary according to the ambient conditions. The amount of these variations greatly affects those parameters as well as the plant incomes. In this paper the effect of ambient temperature as a seasonal variation on a gas power plant has been numerically studied. For this purpose, the gas turbine model and different climate seasonal variations of Ray in Iran are considered in this study. For the model, by using average monthly temperature data of the region, the different effective parameters were compared to those in standard design conditions. The results show that ambient temperature increase will decrease thermal efficiency, electric-power out put and fuel-air ratio of the gas turbine plant whereas increases the specific fuel consumption

Laser absorption spectroscopy of water vapor confined in nanoporous alumina: wall collision line broadening and gas diffusion dynamics.

Science.gov (United States)

Svensson, Tomas; Lewander, Märta; Svanberg, Sune

2010-08-02

We demonstrate high-resolution tunable diode laser absorption spectroscopy (TDLAS) of water vapor confined in nanoporous alumina. Strong multiple light scattering results in long photon pathlengths (1 m through a 6 mm sample). We report on strong line broadening due to frequent wall collisions (gas-surface interactions). For the water vapor line at 935.685 nm, the HWHM of confined molecules are about 4.3 GHz as compared to 2.9 GHz for free molecules (atmospheric pressure). Gas diffusion is also investigated, and in contrast to molecular oxygen (that moves rapidly in and out of the alumina), the exchange of water vapor is found very slow.

Facility Configuration Study of the High Temperature Gas-Cooled Reactor Component Test Facility

Energy Technology Data Exchange (ETDEWEB)

S. L. Austad; L. E. Guillen; D. S. Ferguson; B. L. Blakely; D. M. Pace; D. Lopez; J. D. Zolynski; B. L. Cowley; V. J. Balls; E.A. Harvego, P.E.; C.W. McKnight, P.E.; R.S. Stewart; B.D. Christensen

2008-04-01

A test facility, referred to as the High Temperature Gas-Cooled Reactor Component Test Facility or CTF, will be sited at Idaho National Laboratory for the purposes of supporting development of high temperature gas thermal-hydraulic technologies (helium, helium-Nitrogen, CO2, etc.) as applied in heat transport and heat transfer applications in High Temperature Gas-Cooled Reactors. Such applications include, but are not limited to: primary coolant; secondary coolant; intermediate, secondary, and tertiary heat transfer; and demonstration of processes requiring high temperatures such as hydrogen production. The facility will initially support completion of the Next Generation Nuclear Plant. It will secondarily be open for use by the full range of suppliers, end-users, facilitators, government laboratories, and others in the domestic and international community supporting the development and application of High Temperature Gas-Cooled Reactor technology. This pre-conceptual facility configuration study, which forms the basis for a cost estimate to support CTF scoping and planning, accomplishes the following objectives: • Identifies pre-conceptual design requirements • Develops test loop equipment schematics and layout • Identifies space allocations for each of the facility functions, as required • Develops a pre-conceptual site layout including transportation, parking and support structures, and railway systems • Identifies pre-conceptual utility and support system needs • Establishes pre-conceptual electrical one-line drawings and schedule for development of power needs.

Facility Configuration Study of the High Temperature Gas-Cooled Reactor Component Test Facility

International Nuclear Information System (INIS)

S. L. Austad; L. E. Guillen; D. S. Ferguson; B. L. Blakely; D. M. Pace; D. Lopez; J. D. Zolynski; B. L. Cowley; V. J. Balls; E.A. Harvego, P.E.; C.W. McKnight, P.E.; R.S. Stewart; B.D. Christensen

2008-01-01

A test facility, referred to as the High Temperature Gas-Cooled Reactor Component Test Facility or CTF, will be sited at Idaho National Laboratory for the purposes of supporting development of high temperature gas thermal-hydraulic technologies (helium, helium-Nitrogen, CO2, etc.) as applied in heat transport and heat transfer applications in High Temperature Gas-Cooled Reactors. Such applications include, but are not limited to: primary coolant; secondary coolant; intermediate, secondary, and tertiary heat transfer; and demonstration of processes requiring high temperatures such as hydrogen production. The facility will initially support completion of the Next Generation Nuclear Plant. It will secondarily be open for use by the full range of suppliers, end-users, facilitators, government laboratories, and others in the domestic and international community supporting the development and application of High Temperature Gas-Cooled Reactor technology. This pre-conceptual facility configuration study, which forms the basis for a cost estimate to support CTF scoping and planning, accomplishes the following objectives: (1) Identifies pre-conceptual design requirements; (2) Develops test loop equipment schematics and layout; (3) Identifies space allocations for each of the facility functions, as required; (4) Develops a pre-conceptual site layout including transportation, parking and support structures, and railway systems; (5) Identifies pre-conceptual utility and support system needs; and (6) Establishes pre-conceptual electrical one-line drawings and schedule for development of power needs

Treatment of low-temperature tar-gas mixtures

Energy Technology Data Exchange (ETDEWEB)

Schick, F

1928-07-04

Process for the treating and conversion of low-temperature tar-vapor and gas mixtures in the presence of metals or metal oxides as well as bodies of large surface, without previous condensation of the liquid material to be treated, characterized by the treatment taking place with a mixture of desulfurizing metals and metal oxides which, if necessary, are precipitated on carriers and large surface nonmetal cracking catalysts, such as active carbon and silica gel.

Overview of experimental preparation for the ITER-Like Wall at JET

Energy Technology Data Exchange (ETDEWEB)

Brezinsek, S., E-mail: s.brezinsek@fz-juelich.de [Institut fuer Energieforschung-Plasmaphysik, Forschungszentrum Juelich, Association EURATOM-FZJ, 52425 Juelich (Germany); Culham Centre for Fusion Energy, Abingdon, Oxon OX14 3DB (United Kingdom); Fundamenski, W. [Culham Centre for Fusion Energy, Abingdon, Oxon OX14 3DB (United Kingdom); Eich, T. [Association EURATOM-Max-Planck-Institut fuer Plasmaphysik, D-85748 Garching (Germany); Coad, J.P.; Giroud, C.; Huber, A. [Culham Centre for Fusion Energy, Abingdon, Oxon OX14 3DB (United Kingdom); Jachmich, S. [LPP-ERM/KMS, Association EURATOM-Belgian State (Belgium); Joffrin, E. [Culham Centre for Fusion Energy, Abingdon, Oxon OX14 3DB (United Kingdom); Krieger, K.; McCormick, K. [Association EURATOM-Max-Planck-Institut fuer Plasmaphysik, D-85748 Garching (Germany); Lehnen, M. [Culham Centre for Fusion Energy, Abingdon, Oxon OX14 3DB (United Kingdom); Loarer, T. [Association EURATOM-CEA, CEA Cadarache, 13108 Saint Paul lez Durance (France); Luna, E. de la [Laboratorio Nacional de Fusion, Asociacion EURATOM/CIEMAT, 28040 Madrid (Spain); Maddison, G.; Matthews, G.F.; Mertens, Ph. [Culham Centre for Fusion Energy, Abingdon, Oxon OX14 3DB (United Kingdom); Nunes, I. [Instituto de Plasmas e Fusao Nuclear, Associaccao EURATOM-IST, Lisboa (Portugal); Philipps, V.; Riccardo, V. [Culham Centre for Fusion Energy, Abingdon, Oxon OX14 3DB (United Kingdom); Rubel, M. [Alfven Laboratory, Royal Institute of Technology, Association EURATOM-VR, Stockholm (Sweden)

2011-08-01

Experiments in JET with carbon-based plasma-facing components have been carried out in preparation of the ITER-Like Wall with beryllium main chamber and full tungsten divertor. The preparatory work was twofold: (i) development of techniques, which ensure safe operation with the new wall and (ii) provision of reference plasmas, which allow a comparison of operation with carbon and metallic wall. (i) Compatibility with the W divertor with respect to energy loads could be achieved in N{sub 2} seeded plasmas at high densities and low temperatures, finally approaching partial detachment, with only moderate confinement reduction of 10%. Strike-point sweeping increases the operational space further by re-distributing the load over several components. (ii) Be and C migration to the divertor has been documented with spectroscopy and QMBs under different plasma conditions providing a database which will allow a comparison of the material transport to remote areas with metallic walls. Fuel retention rates of 1.0-2.0 x 10{sup 21} D s{sup -1} were obtained as references in accompanied gas balance studies.

Effects of Gas-Wall Partitioning in Teflon Tubing, Instrumentation and Other Materials on Time-Resolved Measurements of Gas-Phase Organic Compounds

Science.gov (United States)

Pagonis, D.; Deming, B.; Krechmer, J. E.; De Gouw, J. A.; Jimenez, J. L.; Ziemann, P. J.

2017-12-01

Recently it has been shown that gas-phase organic compounds partition to and from the walls of Teflon environmental chambers. This process is fast, reversible, and can be modeled as absorptive partitioning. Here these studies were extended to investigate gas-wall partitioning inside Teflon tubing by introducing step function changes in the concentration of compounds being sampled and measuring the delay in the response of a proton transfer reaction-mass spectrometer (PTR-MS). We find that these delays are significant for compounds with a saturation vapor concentration (c*) below 106 μg m-3, and that the Teflon tubing and the PTR-MS both contribute to the delays. Tubing delays range from minutes to hours under common sampling conditions and can be accurately predicted by a simple chromatography model across a range of tubing lengths and diameters, flow rates, compound functional groups, and c*. This method also allows one to determine the volatility-dependent response function of an instrument, which can be convolved with the output of the tubing model to correct for delays in instrument response time for these "sticky" compounds. This correction is expected to be of particular interest to researchers utilizing and developing chemical ionization mass spectrometry (CIMS) techniques, since many of the multifunctional organic compounds detected by CIMS show significant tubing and instrument delays. These results also enable better design of sampling systems, in particular when fast instrument response is needed, such as for rapid transients, aircraft, or eddy covariance measurements. Additional results presented here extend this method to quantify the relative sorptive capacities for other commonly used tubing materials, including PFA, FEP, PTFE, PEEK, glass, copper, stainless steel, and passivated steel.

High-Temperature Monitoring of Refractory Wall Recession Using Frequency-Modulated Continuous-wave (FM-CW) Radar Techniques

International Nuclear Information System (INIS)

Varghese, B.; DeConick, C.; Cartee, G.; Zoughi, R.; Velez, M.; Moore, R.

2005-01-01

Furnaces are among the most crucial components in the glass and metallurgical industry. Nowadays, furnaces are being operated at higher temperatures and for longer periods of time thus increasing the rate of wear on the furnace refractory lining. Consequently, there is a great need for a nondestructive tool that can accurately measure refractory wall thickness at high temperatures. In this paper the utility of a frequency-modulated continuous-wave (FM-CW) radar is investigated for this purpose

Temperature Gradient Effect on Gas Discrimination Power of a Metal-Oxide Thin-Film Sensor Microarray

Directory of Open Access Journals (Sweden)

Joachim Goschnick

2004-05-01

Full Text Available Abstract: The paper presents results concerning the effect of spatial inhomogeneous operating temperature on the gas discrimination power of a gas-sensor microarray, with the latter based on a thin SnO2 film employed in the KAMINA electronic nose. Three different temperature distributions over the substrate are discussed: a nearly homogeneous one and two temperature gradients, equal to approx. 3.3 oC/mm and 6.7 oC/mm, applied across the sensor elements (segments of the array. The gas discrimination power of the microarray is judged by using the Mahalanobis distance in the LDA (Linear Discrimination Analysis coordinate system between the data clusters obtained by the response of the microarray to four target vapors: ethanol, acetone, propanol and ammonia. It is shown that the application of a temperature gradient increases the gas discrimination power of the microarray by up to 35 %.

Temperature and species measurement in a quenching boundary layer on a flat-flame burner

Energy Technology Data Exchange (ETDEWEB)

Fuyuto, Takayuki; Fujikawa, Taketoshi; Akihama, Kazuhiro [Toyota Central Research and Development Labs., Inc., Nagakute, Aichi (Japan); Kronemayer, Helmut [University of Duisburg-Essen, IVG, Institute for Combustion and Gasdynamics, Duisburg (Germany); BASF SE, Ludwigshafen (Germany); Lewerich, Burkhard; Dreier, Thomas; Schulz, Christof [University of Duisburg-Essen, IVG, Institute for Combustion and Gasdynamics, Duisburg (Germany); Bruebach, Jan [Technical University Darmstadt, EKT, Institute for Energy and Powerplant Technology, Darmstadt (Germany)

2010-10-15

A detailed understanding of transport phenomena and reactions in near-wall boundary layers of combustion chambers is essential for further reducing pollutant emissions and improving thermal efficiencies of internal combustion engines. In a model experiment, the potential of laser-induced fluorescence (LIF) was investigated for measurements inside the boundary layer connected to flame-wall interaction at atmospheric pressure. Temperature and species distributions were measured in the quenching boundary layer formed close to a cooled metal surface located parallel to the flow of a premixed methane/air flat flame. Multi-line NO-LIF thermometry provided gas-phase temperature distributions. In addition, flame species OH, CH{sub 2}O and CO were monitored by single-photon (OH, CH{sub 2}O) and two-photon (CO) excitation LIF, respectively. The temperature dependence of the OH-LIF signal intensities was corrected for using the measured gas-phase temperature distributions. The spatial line-pair resolution of the imaging system was 22 {mu}m determined by imaging microscopic line pairs printed on a resolution target. The experimental results show the expected flame quenching behavior in the boundary layer and they reveal the potential and limitations of the applied diagnostics techniques. Limitations in spatial resolution are attributed to refraction of fluorescence radiation propagating through steep temperature gradients in the boundary layer. For the present experimental arrangements, the applied diagnostics techniques are applicable as close to the wall as 200 {mu}m with measurement precision then exceeding the 15-25% limit for species detection, with estimates of double this value for the case of H{sub 2}CO due to the unknown effect of the Boltzmann fraction corrections not included in the data evaluation process. Temperature measurements are believed to be accurate within 50 K in the near-wall zone, which amounts to roughly 10% at the lower temperatures encountered in

Comparison of microstructural and mechanical properties of joints developed by high temperature brazing, GTAW and laser welding methods on AISI 316 L stainless steel for specific applications in nuclear components

International Nuclear Information System (INIS)

Venkatesu, Sadu; Saxena, Rajesh; Ravi Kumar, R.; Chaurasia, P.K; Murugan, S.; Venugopal, S.

2016-01-01

Fabrication of instrumented irradiation capsule for evaluating the irradiation performance of fuel and structural materials in a nuclear reactor requires development of thin wall joints capable of withstanding high temperature and/or internal pressure. Thin wall joints for high temperature (∼550℃) applications can be made by laser beam welding (LBW), gas tungsten Arc welding (GTAW) and High Temperature Brazing (HLT) method

Numerical simulation on vacuum solution heat treatment and gas quenching process of a low rhenium-containing Ni-based single crystal turbine blade

Directory of Open Access Journals (Sweden)

Zhe-xin Xu

2016-11-01

Full Text Available Numerical heat-transfer and turbulent flow model for an industrial high-pressure gas quenching vacuum furnace was established to simulate the heating, holding and gas fan quenching of a low rhenium-bearing Ni-based single crystal turbine blade. The mesh of simplified furnace model was built using finite volume method and the boundary conditions were set up according to the practical process. Simulation results show that the turbine blade geometry and the mutual shielding among blades have significant influence on the uniformity of the temperature distribution. The temperature distribution at sharp corner, thin wall and corner part is higher than that at thick wall part of blade during heating, and the isotherms show a toroidal line to the center of thick wall. The temperature of sheltered units is lower than that of the remaining part of blade. When there is no shelteration among multiple blades, the temperature distribution for all blades is almost identical. The fluid velocity field, temperature field and cooling curves of the single and multiple turbine blades during gas fan quenching were also simulated. Modeling results indicate that the loading tray, free outlet and the location of turbine blades have important influences on the flow field. The high-speed gas flows out from the nozzle is divided by loading tray, and the free outlet enhanced the two vortex flow at the end of the furnace door. The closer the blade is to the exhaust outlet and the nozzle, the greater the flow velocity is and the more adequate the flow is. The blade geometry has an effect on the cooling for single blade and multiple blades during gas fan quenching, and the effects in double layers differs from that in single layer. For single blade, the cooing rate at thin-walled part is lower than that at thick-walled part, the cooling rate at sharp corner is greater than that at tenon and blade platform, and the temperature at regions close to the internal position is

Surface-Anchored Poly(4-vinylpyridine)–Single-Walled Carbon Nanotube–Metal Composites for Gas Detection

KAUST Repository

Yoon, Bora

2016-08-05

A platform for chemiresistive gas detectors based upon single-walled carbon nanotube (SWCNT) dispersions stabilized by poly(4-vinylpyridine) (P4VP) covalently immobilized onto a glass substrate was developed. To fabricate these devices, a glass substrate with gold electrodes is treated with 3-bromopropyltrichlorosilane. The resulting alkyl bromide coating presents groups that can react with the P4VP to covalently bond (anchor) the polymer–SWCNT composite to the substrate. Residual pyridyl groups in P4VP not consumed in this quaternization reaction are available to coordinate metal nanoparticles or ions chosen to confer selectivity and sensitivity to target gas analytes. Generation of P4VP coordinated to silver nanoparticles produces an enhanced response to ammonia gas. The incorporation of soft Lewis acidic Pd2+ cations by binding PdCl2 to P4VP yields a selective and highly sensitive device that changes resistance upon exposure to vapors of thioethers. The latter materials have utility for odorized fuel leak detection, microbial activity, and breath diagnostics. A third demonstration makes use of permanganate incorporation to produce devices with large responses to vapors of volatile organic compounds that are susceptible to oxidation.

Exhaust Gas Temperature Measurements in Diagnostics of Turbocharged Marine Internal Combustion Engines Part I Standard Measurements

Directory of Open Access Journals (Sweden)

Korczewski Zbigniew

2015-01-01

Full Text Available The article discusses the problem of diagnostic informativeness of exhaust gas temperature measurements in turbocharged marine internal combustion engines. Theoretical principles of the process of exhaust gas flow in turbocharger inlet channels are analysed in its dynamic and energetic aspects. Diagnostic parameters are defined which enable to formulate general evaluation of technical condition of the engine based on standard online measurements of the exhaust gas temperature. A proposal is made to extend the parametric methods of diagnosing workspaces in turbocharged marine engines by analysing time-histories of enthalpy changes of the exhaust gas flowing to the turbocompressor turbine. Such a time-history can be worked out based on dynamic measurements of the exhaust gas temperature, performed using a specially designed sheathed thermocouple.

Effects of gas–wall partitioning in Teflon tubing and instrumentation on time-resolved measurements of gas-phase organic compounds

Directory of Open Access Journals (Sweden)

D. Pagonis

2017-12-01

Full Text Available Recent studies have demonstrated that organic compounds can partition from the gas phase to the walls in Teflon environmental chambers and that the process can be modeled as absorptive partitioning. Here these studies were extended to investigate gas–wall partitioning of organic compounds in Teflon tubing and inside a proton-transfer-reaction mass spectrometer (PTR-MS used to monitor compound concentrations. Rapid partitioning of C8–C14 2-ketones and C11–C16 1-alkenes was observed for compounds with saturation concentrations (c∗ in the range of 3 × 104 to 1 × 107 µg m−3, causing delays in instrument response to step-function changes in the concentration of compounds being measured. These delays vary proportionally with tubing length and diameter and inversely with flow rate and c∗. The gas–wall partitioning process that occurs in tubing is similar to what occurs in a gas chromatography column, and the measured delay times (analogous to retention times were accurately described using a linear chromatography model where the walls were treated as an equivalent absorbing mass that is consistent with values determined for Teflon environmental chambers. The effect of PTR-MS surfaces on delay times was also quantified and incorporated into the model. The model predicts delays of an hour or more for semivolatile compounds measured under commonly employed conditions. These results and the model can enable better quantitative design of sampling systems, in particular when fast response is needed, such as for rapid transients, aircraft, or eddy covariance measurements. They may also allow estimation of c∗ values for unidentified organic compounds detected by mass spectrometry and could be employed to introduce differences in time series of compounds for use with factor analysis methods. Best practices are suggested for sampling organic compounds through Teflon tubing.

Formation of Sclerotic Hydrate Deposits in a Pipe for Extraction of a Gas from a Dome Separator

Science.gov (United States)

Urazov, R. R.; Chiglinstev, I. A.; Nasyrov, A. A.

2017-09-01

The theory of formation of hydrate deposits on the walls of a pipe for extraction of a gas from a dome separator designed for the accident-related collection of hydrocarbons on the ocean floor is considered. A mathematical model has been constructed for definition of a steady movement of a gas in such a pipe with gas-hydrate deposition under the conditions of changes in the velocity, temperature, pressure, and moisture content of the gas flow.