High Pressure Side Research Articles

Radiation of X-Rays in Low-Pressure Gas Using LiNbO<sub>3</sub> Single Crystal

The gas pressure and the types of ambient gas dependence of X-ray intensity were investigated for LiNbO3 single crystals polarized in the c-axis direction at pressures of approximately 1 to 30 Pa. The integrated X-ray intensity showed a local maximum value at the pressure Pmax. Pmax moved to the high-pressure side in the ambient with a large first ionization energy. Pmax was proportional to the Boltzmann factor using the first ionization energy of each ambient gas molecule. The X-ray intensity was approximated using the quadratic function, which was convex upward for the pressure. It was found that one of the causes of the decrease in X-ray intensity on the pressure side higher than Pmax was the adsorption of positive ions on the crystal electric surface.

Short-Pulse High-Power Microwave Surface Flashover at 3 GHz

High-power microwave (HPM)-induced surface flashover is investigated in order to gain a better understanding of this phenomenon and reduce the limitations it imposes on transmitted power levels. This paper builds on previous testing using a magnetron producing 5 MW for 4 mus at 2.85 GHz. Both the previous and current experimental setups are designed to produce a flashover on the high-pressure side of a transmission window without the influence of a triple point. The limitations of the previous experiment included a maximum power of 5 MW and a pulse rise time of 50 ns. The current HPM source is an experimental virtual cathode oscillator (vircator), the output of which has been extensively characterized. The vircator is capable of producing 50-MW peak for 100 ns with an adjustable frequency from 3 to 5 GHz and a rise time of < 4 ns. The dominant modes of the vircator and magnetron are the circular TE11 and rectangular TE10 modes, respectively, with the major electric field component in both setups normal to the direction of propagation, yielding comparable field geometries at the transmission window. The experimental setup permits the study of factors, including gas pressure, composition, temperature, and air speed. Diagnostic equipment allows the analysis of power levels and flashover luminosity with subnanosecond resolution. Additional experimental results, including a detailed analysis of the flashover delay times under various conditions, are compared with data from literature and previous testing. A trend of increasing delay time with pressure is clearly observable, and Eeff/p versus p * r data fall within what has been previously observed in literature primarily for HPM volume breakdown.

Global phase diagram for magnetism and lattice distortion of iron-pnictide materials

We study the global phase diagram of magnetic orders and lattice structure in the Fe-pnictide materials at zero temperature within one unified theory, tuned by both doping and pressure. On the low doping and high pressure side of the phase diagram, there is one single transition, which is described by a $z=2$ mean field theory with very weak run-away flows; on the high doping and low pressure side the transition is expected to split to two transitions, with one O(3) spin density wave transition followed by a z = 3 quantum Ising transition at larger doping. The fluctuation of the strain field fluctuation of the lattice will not affect the spin density wave transition, but will likely drive the Ising nematic transition more mean field like through a linear coupling, as observed experimentally in BaFe_2-xCo_xAs_2.

A simplified ion exchange bead-based KOH electrodialytic generator for capillary ion chromatography

A simple potassium hydroxide electrodialytic generator (EDG) with singe membrane configuration is described. In this setup, one cation exchange resin (CER) bead is used to fabricate the EDG in place of the common membrane sheet. The device is implemented simply in a commercial stainless steel (SS) Tee which serves as both the EDG cartridge and the cathodic electrode. The present EDG has much lower internal volume (∼0.16 (L), which is well suited with capillary ion chromatography system. The device has been tested up pressures to 3200 psi and could be directly deployed on the high-pressure side of the pump. The electrolysis gas can be effectively removed by a segment of PTFE tubing. In the tested range of 0–100 mM, the KOH concentration is generated linearly with the applied current being near-Faradaic efficiency. The device permits both isocratic and gradient operation with good reproducibility, as demonstrated by the analysis of anions.

Counterclockwise exhumation of a hot orogen: The Paleoproterozoic ultrahigh-temperature granulites in the North China Craton

Regional metamorphic belts provide important constraints on the plate tectonic architecture of orogens. We report here a detailed petrologic examination of the sapphirine-bearing ultra-high temperature (UHT) granulites from the Jining Complex within the Khondalite Belt of the North China Craton (NCC). These granulites carry diagnostic UHT assemblages and their microstructures provide robust evidence to trace the prograde, peak and retrograde metamorphic evolution. The P–T conditions of the granulites estimated from X Mg Grt(Mg/Fe + Mg) − X Mg Spr isopleth calculations indicate temperature above 970 °C and pressures close to 7 kbar. We present phase diagrams based on thermodynamic computations to evaluate the mineral assemblages and microstructures and trace the metamorphic trajectory of the rocks. The evolution from Spl–Qtz–Ilm–Crd–Grt–Sil to Spr–Qtz–Crd–Opx–Ilm marks the prograde stage. The Spl–Qtz assemblage appears on the low-pressure side of the P–T space with Spr–Qtz stable at the high-pressure side, possibly representing an increase in pressure corresponding to compression. The spectacular development of sapphirine rims around spinel enclosed in quartz supports this inference. An evaluation of the key UHT assemblages based on model proportion calculation suggests a counterclockwise P–T path. With few exceptions, granulite-facies rocks developed along collisional metamorphic zones have generally been characterized by clockwise exhumation trajectories. Recent evaluation of the P–T paths of metamorphic rocks developed within collisional orogens indicates that in many cases the exhumation trajectories follow the model subduction geotherm, in accordance with a tectonic model in which the metamorphic rocks are subducted and exhumed along a plate boundary. The timing of UHT metamorphism in the NCC ( c. 1.92 Ga) coincides with the assembly of the NCC within the Paleoproterozoic Columbia supercontinent, a process that would have involved subduction of passive margins sediments and closure of the intervening ocean. Thus, the counterclockwise P–T path obtained in this study correlates well with a tectonic model involving subduction and final collisional suturing, with the UHT granulites representing the core of the hot or ultra-hot orogen developed during Columbia amalgamation.

Assessment of blends of CO 2 with butane and isobutane as working fluids for heat pump applications

In the present study, blends R744/R600 and R744/R600a are being proposed as working fluids in heat pumps for medium and high temperature heating applications. COP based performances have been evaluated for zeotropic mixtures of both working fluid pairs for various compositions and compared against that of pure working fluids. Effect of internal heat exchanger on blend based system performance is also presented and finally heat transfer issues in evaporation and condensation are discussed. Results show that due to gliding temperature during evaporation and condensation, the zeotropic blends, instead of pure counterparts, can be employed very effectively in heat pumps for variable temperature or simultaneous cooling and heating applications (e.g., dairy plants) at conventional high side pressure. The blend R744/R600a can be the best alternative refrigerant to R114 for high temperature heating due to superior COP (more than twice) over R600 and R600a and eliminating the requirement of extremely high side pressure of R744 systems.

Thermodynamic and Raman spectroscopic studies on hydrogen+tetra- n-butyl ammonium fluoride semi-clathrate hydrates

Thermodynamic stability and hydrogen occupancy on the hydrogen+tetra- n-butyl ammonium fluoride semi-clathrate hydrate have been investigated by means of phase equilibrium (pressure–temperature) measurements and Raman spectroscopic analyses for two mole fractions, 0.018 and 0.034 (stoichiometric for the cubic structure) of tetra- n-butyl ammonium fluoride aqueous solutions. In the case of higher concentration (0.034), the stability boundary curve of hydrogen+tetra- n-butyl ammonium fluoride semi-clathrate hydrate locates at about 23 K higher temperature than that of hydrogen+tetrahydrofuran mixed gas hydrate. The storage capacity of hydrogen in the cubic structure for the hydrogen+tetra- n-butyl ammonium fluoride semi-clathrate hydrate is smaller than that of hydrogen+tetrahydrofuran mixed gas hydrate. In the case of hydrate prepared from the lower concentration (0.018) of aqueous solution, the Raman spectra and phase behavior reveal that the cubic structure of semi-clathrate hydrate is changed to a different one at about 9 MPa and 299.2 K. The new structure can entrap larger amount of hydrogen than the cubic one. The stability boundary curve of hydrogen+tetra- n-butyl ammonium fluoride semi-clathrate hydrate obtained in the aqueous solution of lower mole fraction (0.018) is shifted to slightly low-temperature or high-pressure side from that of higher mole fraction (0.034).

214 管路・伝熱管の肉厚変化の診断技術に関する研究 : 第1報:直管路を水が流れる場合(セッション6 同定)

Major items of equipment of process plants are piping and heat exchangers. Their typical troubles with aging are mainly caused by scale adhesion and erosion-corrosion. The former decreases flow rate, pressure and heat transfer performance, the latter breaks piping and heat exchanger tubes. Therefore, the purpose of this study is to derive the diagnostic method of pipe thickness which is more effective than the monitoring pressure. In this paper, the diagnostic method of pipe thickness in water line is developed experimentally. It is based on the phase of the transfer function of low-side pressure to high-side pressure in the test section. The experimental results show that this diagnostic method is superior to monitoring pressure on detecting a changing pipe thickness.

Thermodynamic stability of hydrogen [formula omitted] tetra- n-butyl ammonium bromide mixed gas hydrate in nonstoichiometric aqueous solutions

Phase equilibrium (pressure–temperature) relations of the hydrogen + tetra- n-butyl ammonium bromide mixed gas hydrate system have been measured for various concentrations of tetra- n-butyl ammonium bromide aqueous solutions. The three-phase equilibrium curves obtained in the present study are shifted to the low-temperature or high-pressure side from that of the stoichiometric tetra- n-butyl ammonium bromide solution. Each three-phase equilibrium curve of hydrogen + tetra- n-butyl ammonium bromide mixed gas hydrate converges at the atmospheric equilibrium point of the pure tetra- n-butyl ammonium bromide hydrate for the mother aqueous solution of same mole fraction. The hydrate-cage occupancy of hydrogen in the hydrogen + tetra- n-butyl ammonium bromide mixed gas hydrate is in variable in a range of tetra- n-butyl ammonium bromide mole fraction from 0.006 to 0.070 in the aqueous solution. Hydrogen is entrapped only in the small cages of tetra- n-butyl ammonium bromide hydrates.

Clathrate Dissociation Conditions for Methane + Tetra-n-butyl Ammonium Bromide (TBAB) + Water

Hydrate equilibrium data of the CH4 + tetra-n-butyl ammonium bromide (TBAB) + water have been measured by using the isothermal pressure search method for four components of TBAB aqueous solutions. The three-phase equilibrium lines obtained in the present study are shifted to the low-temperature or high-pressure side from that of the stoichiometric TBAB solution. Moreover, methane uptake into semi-clathrates is confirmed by a shift in the clathrate regions when methane is present. The experiments are carried out in the pressure range of (0.5 to 11) MPa and in the temperature range of (281.15 to 295.15) K.

Experimental validation of a prototype ejector designed to reduce throttling losses encountered in transcritical R744 system operation

This study presents experimental results obtained from a transcritical R744 system using a refrigerant ejector. The results were compared to that of a conventional system with an expansion valve. For the test conditions considered, the cooling capacity and COP simultaneously improved by up to 8% and 7%, respectively. Experiments were analyzed to quantitatively assess the effects on system performance as a result of changes in basic ejector dimensions such as motive nozzle and diffuser sizing. Small angles of 5° yielded best results for the static pressure recovery of the high-speed two-phase flow entering the diffuser. Experiments confirmed that like in a conventional transcritical R744 system with expansion valve, the high-side pressure control integrated into the ejector could be used to maximize the system performance. Numerical simulation results helped identifying this basic trend. Due to difficulties in the ejector throat pressure measurements, a more practical performance metric was introduced in order to quantify overall ejector efficiencies. According to this definition, the prototype ejector was able to recover up to 14.5% of the throttling losses.

Improved rotor profiling based on the arbitrary sealing line for twin-screw compressors

A design method for the rotor profile of twin-screw compressor from an arbitrary sealing line is presented. The sealing line is divided into several functional segments that control the high-pressure side and the low-pressure side performances independently. Each functional segment is fitted by cubic spline and the shape of the segment can be adjusted by moving the control points of the cubic spline. Based on the shape of the sealing line, the performance of the compressor can be directly calculated and the corresponding rotor profiles are derived considering the non-undercutting condition. A numerical example which considers the geometric constraints of rotor profiles is presented to demonstrate the flexibility and stability in parametric study of the rotor design.

Hyperfiltration of nickel sulphate solutions through silty sandstone and its effect on hydraulic conductivity

Hyperfiltration (reverse osmosis) and subsequent precipitation of minerals from the hyperfiltrated solution are processes that potentially decrease the hydraulic conductivity of porous media. These processes were demonstrated by hyperfiltrating NiSO 4 solutions through fine-grained sandstone. The mineral precipitates occur in very small (mm sized) layers at the high-pressure side of the samples where they create zones of lowered hydraulic conductivity (2–3 orders of magnitude lower than initial). The total amount of precipitates is very small compared to the dissolved mass which was passed through the membrane. Hyperfiltration-induced precipitates and the resulting lowering of hydraulic conductivities were observed at solute saturations as low as 10%. Nevertheless, at saturations higher than 50% the conductivity reduction strongly increased. Full reversibility of the hydraulic conductivity reduction by extensive re-flushing with water was only obtained at low initial solute saturations (10%). This indicates that precipitated minerals in many pores are susceptible only to very slow, diffusion-controlled re-dissolution.

Hydrodynamics and membrane seal capacity

AbstractThe impact of hydrodynamic groundwater movement on the capacity of seals is currently in debate. There is an extensive record of publication on seals analysis and a similar history on petroleum hydrodynamics yet little work addresses the links between the two. Understanding and quantifying the effects of hydrodynamic flow has important implications for calibrating commonly used seal capacity estimation techniques. These are often based on measurements such as shale gouge, clay smear or mercury porosimitry where membrane sealing is thought to occur. For standard membrane seal analysis, seal capacity is estimated by quantifying capillary pressure‐related measurements and calibrating them with a large observational database of hydrocarbon column heights and measured buoyancy pressures. The seal capacity estimation process has historically been adjusted to account for a number of different generic trapping geometries. We define the characteristics of these geometries from a hydrodynamics viewpoint in order to fine‐tune the seal capacity calibration process. From theoretical analyses of several simplified trapping geometries, it can be concluded that generally, the high pressure side of the seal should be used as the water pressure gradient with which to calculate buoyancy pressure. Secondly, trap geometries where hydrocarbon is reservoired on both sides of a fault are not useful for estimating across fault seal capacity.

Thermodynamic Stability of H2 + Tetrahydrofuran Mixed Gas Hydrate in Nonstoichiometric Aqueous Solutions

Phase equilibria (pressure−temperature relations) of the H2 + tetrahydrofuran mixed gas hydrate system have been measured for various concentrations of tetrahydrofuran aqueous solutions. The three-phase equilibrium lines obtained in the present study are shifted to the low-temperature or high-pressure side from that of the stoichiometric THF solution. Each three-phase equilibrium line of H2 + tetrahydrofuran hydrate converges at the three-phase equilibrium line of the pure tetrahydrofuran hydrate. At the cross point on the lines, the tetrahydrofuran concentration of mother aqueous solution agrees with each other. The Raman spectra of H2 and tetrahydrofuran for the H2 + tetrahydrofuran mixed gas hydrate do not change with the variation of tetrahydrofuran mole fraction from 0.010 to 0.130 in the aqueous solution.

1016 CAEによる自動車部品用製造工具の高性能化(表面改質による機械の高性能化)

The press working is widely used from the height of mass production and the economy for the processing of the steel board for the car. Because the problem named wear-out, burning in the press working coming in contact by the high side pressure of the metal, the coating film to the surface of the metal mold has been introduced as measures. However, Widely used of high tension steel occurs problems film is damaged and film detachment by more load to shear their steels. So the mechanism of the damage was clarified in this research by the stress analysis that used digital engineering like CAD and CAE. In addition, try to make reduction of stress in damage points by changes of shape design.

Dynamic characteristics of an air-to-water heat pump under frosting/defrosting conditions

The dynamic characteristics of a medium air-to-water heat pump with multi-circuit evaporator controlled by the thermostatic expansion valve (TEV) under the frosting/defrosting conditions were investigated experimentally. The airflow maldistribution often occurs if the fin-and-tube heat exchangers in a medium heat pump are arranged in V-type or W-type position with the fan at the top. The experimental results show that the airflow maldistribution will result in the intermittent or unceasing hunting during the frosting period, which is not published in public yet. The airflow uniformity causes every circuit to see the different airflow rates. The liquid refrigerant was not evaporated completely in some circuits with the less airflow rate and a little liquid refrigerant flowed out at the outlet, which resulted in less superheat than the necessary MSS (minimum-stable-signal) of the TEV at the outlet of the evaporator. The TEV had the intermittent hunting during the first two-thirds of the frosting period. Afterwards, the combination of the airflow maldistribution and the airflow drop caused by the frost blocking resulted in more liquid refrigerant flowing out of the evaporator. Hence, the TEV had the unceasing hunting during the last one-third of the frosting period. Finally, the operating parameters for both the low-pressure and the high-pressure sides have the intermittent or unceasing hunting during the frosting period, which synchronized with that of the TEV.

Stiffness and Efficiency Optimization of a Hydrostatic Laser Surface Textured Gas Seal

Microdimples generated by laser surface texturing (LST) can be used to enhance performance in hydrostatic gas-lubricated mechanical seals. This is achieved by applying microdimples with high area density over a certain portion of the sealing dam width adjacent to the high-pressure side, leaving the remaining portion untextured. The textured portion provides an equivalent larger gap that results in converging clearance in the direction of pressure drop and hence, hydrostatic pressure buildup, similar to that of a radial step seal. A mathematical model based on the solution of the Reynolds equation for compressible Newtonian fluid in a narrow gap between two nominally parallel stationary surfaces is developed. A detailed dimensionless analysis of the texturing parameters is performed to achieve maximum gas film stiffness with minimum gas leakage.

Gap Flows through Idealized Topography. Part II: Effects of Rotation and Surface Friction

Abstract Numerical simulations are conducted of geostrophically balanced flow over an isolated mountain cut by a horizontal gap. The relative importance of the along-gap synoptic-scale pressure gradient and terrain-induced mesoscale circulations for the generation of gap winds was examined by changing the direction of the synoptic-scale wind relative to the topography. In all cases, the forcing associated with mesoscale circulations generated by the mountain was at least as significant as the synoptic-scale pressure gradient. In the cases where a component of the large-scale flow was directed perpendicular to the ridge, the dynamics were dominated by either the vertical momentum fluxes due to mountain lee waves or by mesoscale pressure gradients associated with upstream blocking or lee troughing. Mesoscale circulations were also important when the large-scale flow was parallel to the ridge because surface friction turned the low-level winds toward the high pressure side of the ridge, partially blocking the flow and enhancing the along-gap pressure gradient. The flow in the interior of a very long uniform gap was also simulated for a case with the synoptic-scale winds parallel to the ridge so that the synoptic-scale pressure gradient was down the gap. The flow in the interior of the long gap was not horizontal and not in a simple dynamical balance between acceleration, the pressure gradient force, and surface friction. Even the flow in the lowest 150 m was gradually subsiding. Subsidence and lateral momentum flux convergence at low levels near the center of the gap were important contributors to the mass and along-gap momentum budgets.

Characterisation of active and porous sublayers of composite membranes from hydrodynamic and electrical measurements

Composite membranes can be considered as a series association of two homogeneous elements coupled in series, which present different structural and transport properties [1]: a thin and dense active layer, and a thick but porous support to give mechanical stability to the whole system. Although it is commonly assumed the active (or skin) layer controls membrane selectivity and fluxes, the porous sublayer can also slightly affect them [2]. For determining transport behavior of composite membranes, it is necessary to know the characteristic coefficients for each layer but information on the active/ porous layer interface is also of interest. In this work, hydrodynamic and impedance spectroscopy measurements were carried out with a composite reverse osmosis polyamide/ polysulfone membrane with various electrolytes at different concentrations, to compare membrane parameters depending on the electrolyte type. Two opposite membrane configurations were used for hydrodynamic filtration experiments, the active layer or the porous sublayer facing the high-pressure side, which allows the estimation of average active layer rejection coefficient (sa) and salt permeability (wa), active/porous layers intermediate concentration (Ci) and salt permeability in the porous sublayer (wp). Impedance spectroscopy (IS) measurements were carried out for a wide range of frequency with the membrane separating an electrolyte solution of a given concentration and it is a successful tool to determine the electrical properties (electrical resistance and capacitance) of heterogeneous systems formed by a series array of layers with different electrical/structural properties by using equivalent circuits as models [3–4].