Superhigh Pressures Research Articles

Estimating the Steam Quality in Power-Generating Boilers from Electrical Conductivity and pH Measurements

The quality of steam produced by boilers is strictly standardized and must be maintained whatever the quality of makeup water and whatever the composition of the boiler unit’s thermal cycle equipment. Under the conditions of constantly improved instruments for chemical monitoring, it becomes possible to develop measurement systems using which the main standardized and diagnostic steam quality indicators can be monitored by measuring the electric conductivity and pH of cooled samples. Unlike boilers operating at a pressure of 13.8 MPa and higher, steam boilers for steam pressures equal to 9.8 and 3.9 MPa—and also industrial heat recovery steam generators—operate with steam that has a higher content of salts and carbon dioxide; in addition, it contains ammonia, which enters into steam from boiler water. Steam quality is often estimated using the two-quadrant nomographic chart of Mostofin, who proposed it more than 50 years ago. In using certain computation algorithms, it is possible to calculate the standardized and diagnostic steam quality indicators, such as concentrations of sodium, chlorides, ammonia, carbon dioxide, and salt content. The article presents an algorithm for estimating the concentrations of the above-mentioned impurities for cooled live steam samples of power-generating boilers operating at pressures below 10.0 MPa, and boilers for superhigh and supercritical pressures, and industrial heat recovery steam generators, including the combined-cycle power plant units. Examples of using the calculation procedure for analyzing the steam quality in industrial boilers are given.

Anomalies in the dynamics of a metallic glass-forming liquid under super-high pressure

The atomic dynamics of a Zr50Cu50 metallic glass-forming liquid has been investigated in isothermal compression by using molecular dynamics simulations. It is found that the mean square displacement (MSD) for Zr is unexpectedly larger than that for Cu under super-high pressures. This interesting result challenges our understanding that the Cu atoms are always faster than Zr atoms in normal liquids, suggesting that the atomic dynamics for Zr becomes extraordinary under super-high pressure. We found that the shorter-bonded Zr atoms can be formed under-super high pressure because of the remarkable softness of Zr-Zr bonding ways. Further studies suggest that this special local structure is responsible for the unexpected atomic dynamics of Zr. These results shed light on the understanding of the inimitable dynamics in Zr-based metallic glass-forming liquids under super-high pressure.

Estimation of Dense Plasma Temperature Formed under Shock Wave Cumulation.

The research was carried out by means of implosion plasma generators with conical and hemispherical compression chambers to conduct a quantitative assessment of the boundary temperature of super dense plasma jets. It was proved experimentally that nuclear transformations in metals are caused by the impact of super dense plasma jets (11, ..., 12) × 103 kg/m3. The boundary temperature of these jets was evaluated. It was estimated that the nominal boundary temperature of the studied implosion plasma generators is 106 К. The pressure in the target at the penetration of the super dense jet (~12,000 kg/m3) at the speed of 28,000 m / sec is more than 30 ТPa. The boundary temperature was estimated and proved to depend on the pre-determined values only slightly. It was experimentally established that stable isotopes of manganese Mn55 (up to 27%) are formed in iron targets as a result of high temperature plasma jet penetration. The appearance of manganese must be related to iron transformation into stable isotopes Fe56 and Fe54. The obtained results may be applied for investigating structural changes in metals under the conditions of impulsive super high temperatures and pressures. This method can be also used as a testing ground for studying the physical conditions of forming chemical elements as well as super dense plasma jets.

Thermobaric depth settings of sedimentary rock basins and their fluid dynamics: Communication 3. Superhigh pressures in the stratisphere and salt diapirs

The article discusses the patterns of location and the conditions for the formation of salt diapirs. Their formation is associated with thick salt cjmpleses in which phase transformations within closed physicochemical systems form ultrahigh pressures. The latter are the cause of the flow of salts and their penetration through tectonic cracks and fractures to the earth's surface. The similarity of the formation of salt diapirs and mud volcanoes is emphasized. The possibility of the influence of ultrahigh pressures on the autonomous folding of the sedimentary cover is assumed.

Thermobaric Depth Settings of Sedimentary Rock Basins and Their Fluid Dynamics: Communication 3. Superhigh Pressures in the Stratisphere and Salt Diapirs

Thermobaric Depth Settings of Sedimentary Rock Basins and Their Fluid Dynamics: Communication 3. Superhigh Pressures in the Stratisphere and Salt Diapirs

Thermobaric depth settings of sedimentary rock basins and their fluid dynamics: Сommunication 2. Superhigh pressures and mud volcanoes

The article discusses the patterns of placement of mud volcanoes, their spatial connection with tectonic faults, anticlinal uplifts, oil and gas fields. The connection of mud volcanic activity with ultrahigh pressures arising in the clay strata of the stratisphere as a result of phase transformations of clay minerals and organic matter is argued. The role of earthquakes in the formation of fractured clays, increasing their permeability and the formation of mud crates is emphasized. On the example of the mud volcano Aligula (Turkmenistan), the processes of dilution of sandstones and clays, the formation of volcanic mud-crates are considered.

Thermobaric Depth Settings of Sedimentary Rock Basins and Their Fluid Dynamics: Communication 2. Superhigh Pressures and Mud Volcanoes

Thermobaric Depth Settings of Sedimentary Rock Basins and Their Fluid Dynamics: Communication 2. Superhigh Pressures and Mud Volcanoes

Thermobaric Depth Settings of Sedimentary Rock Basins and Their Fluid Dynamics: Communication 1. Zonation of the Stratispheric Structure and Constraints of Anomalous High and Superhigh Fluid Pressures

The paper addresses zonation of the stratisphere: thermobaric conditions in its deep zones with anomalous high (AHP) and superhigh (SHP) fluid pressures, as well as main types of fluid-dynamic setting in the upper zone. Mechanisms of the clay dehydration and processes of oil-and-gas formation governing the development of superhigh fluid pressures in the lower zone of rock formation are also discussed.

HYPERSONIC WIND TUNNELS BASED ON PRESSURE MULTIPLIERS PART I, PRACTICAL REQUIREMENTS: SCHEMES OF HYPERSONIC WIND TUNNELS

Various technologies used to obtain hypersonic gas flows (nitrogen or air) in aerodynamic research of aircraft models designed for various purposes and scramjet elements, which ensure the possibility of modeling close-to-natural flight conditions in hypersonic wind tunnels (HWTs) at Mach numbers ranging from 5 to 25, are considered. Schemes of short-duration HWTs based on pressure multipliers for implementation of these technologies are presented. The principal issues related to determining the required characteristics of HWT elements at high and super-high pressures of the test gas are described. The capabilities of the various HWT schemes are estimated. It is shown that the proposed HWTs with stagnation pressures up to 10 kbar, flow diameter in the test section equal to 1 m, and moderate temperatures in the heaters used in test gas preheating offer the possibility of aerodynamic testing in the range of Mach numbers from 5 to 25 with simultaneous modeling of flight conditions in terms of Reynolds numbers up to 107–109, and also Mach numbers with elevated values of the flow velocity, density, static pressure, static temperature, and dynamic pressure with test duration from 0.1 to 1 s and above. The data reported in the present paper can serve as a scientific basis for the development of industrial HWTs with pressure multipliers for modeling flight conditions at high Mach and Reynolds number values.

Generation of runaway electrons beams during the breakdown of high-pressure gases

Generation of run-away electrons in SF6, CO2, argon and nitrogen at high and super high pressures is studied. Super-short avalanches electron beams (SAEB) was obtained and measured with a collector at pressures up to 0.3, 0.7, 1.0 and 1.2 MPa in SF6, CO2, argon and nitrogen, respectively. The SAEB duration was shown to be ∼60 ps (FWHM) and gas composition has only minor effect on the duration. It was found that in a gap of 4 mm in SF6, CO2, argon and nitrogen at pressure up to 0.3, 0.7, 1.0 и 1.2 MPa the voltage pulse duration (FWHM) and amplitude increase with pressure.

Experimental investigation of effects of super high injection pressure on diesel spray and induced shock waves characteristics

Modern diesel engines employ higher injection pressure in the common-rail injection system that utilizes high-speed fuel jet to achieve rapid fuel-air mixing for spray atomization improvement. However, the spray characteristics under super high pressure are not well understood. To provide more information on spray characteristics, both the macro- and micro-characteristics of spray have been investigated under super high pressures (up to 300MPa) via an experimental method. The spray penetration and spray cone angle were measured using a high speed camera and the microscopic characteristic of Sauter mean diameter (SMD) was obtained via Malvern Spray Tec to analyze the influence of super high injection pressure on diesel spray atomization. Induced shock waves were captured using a Schlieren system when the spray tip velocity was greater than the local sound velocity accompanied by diesel spray. The results obtained show that higher injection pressures lead to larger spray velocities and a smaller shock wave angle if it exists, with connection between spray and shock waves, and generates a smaller SMD with less decreasing amplitude. Additionally, two different types of leading shock waves—bow and oblique shock wave appeared sequentially with increasing injection pressure.

Simplified wide-range equations of state for benzene and tetradecane

The equations of state for benzene, tetradecane, and their deuterated counterparts are derived on the basis of the original method of constructing the wide-range equations of state for hydrocarbon liquids in an analytical form. The equations describe gas and liquid phases at intensive gas-dynamic processes with consideration of evaporation and condensation and include dissociation and ionization processes associated with super-high pressures and temperatures.

Equation of state of compounds of lithium isotopes with hydrogen isotopes

A semi-empirical wide-range equation of state of compounds of lithium isotopes with hydrogen isotopes is proposed. This equation allows thermodynamic properties to be calculated both in the range of comparatively small densities, pressures, and energies available for experimental studies and in the range of superhigh densities, pressures, and energies where the states can only be estimated at the moment by calculations in accordance with theoretical models. The equation of state contains empirical functions, which allow the composition of the isotopes and the influence of the hydroxide admixture on the compound properties to be taken into account. The capabilities of the equation of state are demonstrated by an example of the description of experimental and numerical data characterizing thermodynamic and thermophysical properties of several compounds of lithium and hydrogen isotopes.

Pressure-induced structural transformations and the anomalous behavior of the viscosity in network chalcogenide and oxide melts

It is known that a number of compressed melts undergo structural phase transitions. Data on the structural changes at high pressures in chalcogenides (AsS, As2S3) and oxide (B2O3) melts with a network structure have been reviewed. Viscosity is one of the fundamental physical properties of a liquid. For various melts, it varies in a very wide range. Structural transformations in melts induce the corresponding changes in all physical properties, in particular viscosity. The measurements of the viscosity of a number of melts at high pressures and temperatures by the radiographic method have been reported. Changes in the viscosity by several orders of magnitude have been detected when the pressure is varied by several gigapascals. The diffusion mechanism in network-structure melts at various pressures has been analyzed. The prediction of the behavior of the viscosity of various melts at superhigh pressures is of high importance for the physics of glass transition, geophysics, and materials science.

Glassy dynamics under superhigh pressure

Nearly all glass-forming liquids feature, along with the structural alpha-relaxation process, a faster secondary process (beta relaxation), whose nature belongs to the great mysteries of glass physics. However, for some of these liquids, no well-pronounced secondary relaxation is observed. A prominent example is the archetypical glass-forming liquid glycerol. In the present work, by performing dielectric spectroscopy under superhigh pressures up to 6 GPa, we show that in glycerol a significant secondary relaxation peak appears in the dielectric loss at P>3 GPa. We identify this beta relaxation to be of Johari-Goldstein type and discuss its relation to the excess wing. We provide evidence for a smooth but significant increase in glass-transition temperature and fragility on increasing pressure.

P. W. Bridgman's contributions to the foundations of shock compression of condensed matter

Based on his 50-year career in static high-pressure research, P. W. Bridgman (PWB) is the father of modern high-pressure physics. What is not generally recognized is that Bridgman was also intimately connected with establishing shock compression as a scientific tool and he predicted major events in shock research that occurred up to 40 years after his death. In 1956 the first phase transition under shock compression was reported in Fe at 13 GPa (130 kbar). PWB said a phase transition could not occur in a ~microsec, thus setting off a controversy. The scientific legitimacy of shock compression resulted 5 years later when static high-pressure researchers confirmed with x-ray diffraction the existence of epsilon-Fe. Once PWB accepted the fact that shock waves generated with chemical explosives were a valid scientific tool, he immediately realized that substantially higher pressures would be achieved with nuclear explosives. He included his ideas for achieving higher pressures in articles published a few years after his death. L. V. Altshuler eventually read Bridgman's articles and pursued the idea of using nuclear explosives to generate super high pressures, which subsequently morphed today into giant lasers. PWB also anticipated combining static and shock methods, which today is done with pre-compression of a soft sample in a diamond anvil cell followed by laser-driven shock compression. One variation of that method is the reverberating-shock technique, in which the first shock pre-compresses a soft sample and subsequent reverberations isentropically compress the first-shocked state.

Mechanisms of development of superhigh pressures under conditions of propagation of explosion waves in conical cavities

In this study, numerical simulation methods are used for investigating the processes of propagation in a conical cavity (conical target) of weak shock waves caused by the blast of a microcharge in combustible mixture outside of the cone volume. A more general question is considered: how do the parameters of the medium at the cone vertex depend on whether it was a neutral gas (air) or combustible mixture (hydrogen-air) that filled the cone initially? Comparison is made of the maximal attainable pressures in the cases where the cone is filled with a combustible mixture and in the cases where the cone contains a neutral gas (air). The leading physical factors are identified and substantiated, which provide for attaining extremely high pressures in narrowing volumes. The problem under consideration is of applied importance from the standpoint of predicting the development of emergencies caused by the propagation of explosion waves in volumes filled with combustible gas.

Diamond-hard alloy macrocomposite material: Development and application

A new diamond-hard alloy macrocomposite material consisting of diamond grits (0.5–0.8 mm or more in size) and a WC-Co matrix has been developed. The material is characterized by high mechanical properties of the matrix (the same as for WC-Co monolithic hard alloys) while diamonds remain completely intact (no graphitization or dissolution in cobalt melt). This process does not require superhigh pressures. Hard-alloy samples sintered beforehand in conditions that ensure the maximum mechanical properties (1450–1500°C, 30–60 min holding) are used as initial materials. Hollows (cells) or ditches of specific sizes (depth, width) are made in these samples with mechanical or electrophysical methods, and then diamond crystals (grits) commensurate with the hollows, cells, or ditches are placed in them. Vacuum infiltration (brazing) at moderate temperatures (900–1150°C) with adhesion-active alloys (or metallized diamonds) is the final stage in the formation of the composite. Therefore, strong adhesion-mechanical fixation of diamond grits in the hard-alloy matrix is ensured. The new material is efficiently used in diamond bits.

High pressures and temperatures in the bubble liquid when it flows through the nozzle

The stationary flow of a bubble gas-liquid mixture in a nozzle of circular cross-section is considered. The possibility of realizing superhigh temperatures and pressures in the gas phase at the nozzle site near the minimum cross section is analyzed. The effect of the parameters (the initial radius and the volume content of bubbles that determine the composition of the volume flow of liquid fed into the nozzle) on the flow pattern is studied.

Electrical Characteristics of NaCl at Frequencies of 1-100 kHz at Superhigh Pressures. Application of an Impedance Spectroscopy

Electrical Characteristics of NaCl at Frequencies of 1-100 kHz at Superhigh Pressures. Application of an Impedance Spectroscopy