High Pressure Generation Research Articles

Centrifuge model test of an irrigation-induced loess landslide in the Heifangtai loess platform, Northwest China

The Heifangtai platform in Northwest China is famous for irrigation-induced loess landslides. This study conducted a centrifuge model test with reference to an irrigation-induced loess landslide that occurred in Heifangtai in 2011. The loess slope model was constructed by whittling a cubic loess block obtaining from the landslide site. The irrigation water was simulated by applying continuous infiltration from back of the slope. The deformation, earth pressure, and pore pressure were investigated during test by a series of transducers. For this particular study, the results showed that the failure processes were characterized by retrogressive landslides and cracks. The time dependent reductions of cohesion and internal friction angle at basal layer with increasing pore-water pressure were responsible for these failures. The foot part of slope is very important for slope instability and hazard prevention in the study area, where concentration of earth pressure and generation of high pore-water pressures would form before failures. The measurements of earth pressure and pore-water pressure might be effective for early warning in the study area.

New Device and Technology for High Speed Hydroforming

In the article a new production device is presented that combines the methodologies of high speed forming with conventional hydroforming. The result is a robust production system that can be easy controlled by the use of standard industrial components. The new system can be used as well for high automated production systems for mass production of small tubular and sheet metal parts as for the flexible manufacturing of workpieces with larger dimensions. The device is in principle a hydraulic driven high speed pressure generator that can be mounted directly on a hydroforming tool. Moreover, an additional drive for the axial feed of the tube is installed. In the paper the idea, the design of the device and the technical data is explained. Furthermore, the results of hydroforming experiments are presented and an overview on the specifications and the advantages of the new process is given. The strain rate is measured for an example workpiece and compared to the theoretical value. A first view on the forming limits is a further important topic of the paper. For the investigated copper tube, the forming limits are extended compared to a quasi-static hydroforming test.

The exergy and energy level difference graphic analysis of a CCHP system under compressor inlet air throttling (IAT) operating strategy

The part-load performance of combined cooling, heating and power (CCHP) system based on exergy and energy level graphic analysis under compressor inlet air throttling (IAT) operating strategy is presented in this paper. The results show that the combustor (COMB) is found to have the largest exergy destruction followed by high-pressure generator (HPG). Compared with the reducing turbine inlet temperature (TIT) operating strategy, the exergy destruction of COMB is decreased under IAT operating strategy; however, the opposite result is presented in HPG. A new graphic analysis based on energy level difference is proposed to indicate the potential to enhance the thermodynamics performance of the components under different operating strategies. The decrease of the energy level difference in the COMB and HPG is a most positive way to decrease the exergy destruction with IAT and TIT operation strategies.

Effect of the ortho-Hydroxyl Groups on a Bipyridine Ligand of Iridium Complexes for the High-Pressure Gas Generation from the Catalytic Decomposition of Formic Acid.

The hydroxyl groups of a 2,2'-bipyridine (bpy) ligand near the metal center activated the catalytic performance of the Ir complex for the dehydrogenation of formic acid at high pressure. The position of the hydroxyl groups on the ligand affected the catalytic durability for the high-pressure H2 generation through the decomposition of formic acid. The Ir complex with a bipyridine ligand functionalized with para-hydroxyl groups shows a good durability with a constant catalytic activity during the reaction even under high-pressure conditions, whereas deactivation was observed for an Ir complex with a bipyridine ligand with ortho-hydroxyl groups (2). In the presence of high-pressure H2 , complex 2 decomposed into the ligand and an Ir trihydride complex through the isomerization of the bpy ligand. This work provides the development of a durable catalyst for the high-pressure H2 production from formic acid.

Robust circadian clock oscillation and osmotic rhythms in inner medulla reflecting cortico-medullary osmotic gradient rhythm in rodent kidney

Circadian clocks in mammals function in most organs and tissues throughout the body. Various renal functions such as the glomerular filtration and excretion of electrolytes exhibit circadian rhythms. Although it has been reported that the expression of the clock genes composing molecular oscillators show apparent daily rhythms in rodent kidneys, functional variations of regional clocks are not yet fully understood. In this study, using macroscopic bioluminescence imaging method of the PER2::Luciferase knock-in mouse kidney, we reveal that strong and robust circadian clock oscillation is observed in the medulla. In addition, the osmotic pressure in the inner medulla shows apparent daily fluctuation, but not in the cortex. Quantitative-PCR analysis of the genes contributing to the generation of high osmotic pressure or the water re-absorption in the inner medulla, such as vasopressin receptors (V1aR, V2R), urea transporter (UT-A2) and water channel (Aqp2) show diurnal variations as well as clock genes. Deficiency of an essential clock gene Bmal1 impairs day-night variations of osmotic pressure gradient in the inner medulla, suggesting that circadian clocks in the medulla part of the kidney may regulate the circadian rhythm of cortico-medullary osmotic pressure gradient, and may contribute physiological day-night rhythm of urination.

Generation of high pressures by short-pulse low-energy laser irradiation

The goal of this paper is twofold: first, we demonstrate shock generation with ultra-short (24 fs) and low-energy (J) laser pulse, following the energy deposition in the target by fast electrons; second, we show that such shocks can be used to provide information on compressed matter. For a target with thickness we have clearly inferred the formation of a shock wave with pressure . We have also measured the color temperature of the emitting target rear side at breakout time , which is in good agreement with predictions from equation-of-state models (SESAME tables) and hydrodynamic simulations.

Swift heavy ion induced modifications in optical and electrical properties of cadmium selenide thin films

The modification in various properties of thin films using high energetic ion beam is an exciting area of basic and applied research in semiconductors. In the present investigations, cadmium selenide (CdSe) thin films were deposited on ITO substrate using electrodeposition technique. To study the swift heavy ion (SHI) induced effects, the deposited thin films were irradiated with 120 MeV heavy Ag9+ ions using pelletron accelerator facility at IUAC, New Delhi, India. Structural phase transformation in CdSe thin film from metastable cubic phase to stable hexagonal phase was observed after irradiation leading to decrease in the band gap from 2.47 eV to 2.12 eV. The phase transformation was analyzed through X-ray diffraction patterns. During SHI irradiation, Generation of high temperature and pressure by thermal spike along the trajectory of incident ions in the thin films might be responsible for modification in the properties of thin films. Open image in new window

Experimental study on LiCl solution falling-film generation process outside a vertical tube

For the purpose of the development of a generator with higher performance utilizing LiCl/H2O as the working pair in a two-stage absorption refrigeration system, an experimental investigation of LiCl solution falling film generation outside a vertical tube as the high-pressure stage solution cycle was conducted. An experimental setup was established to study heat and mass transfer process in a falling-film generator for LiCl/H2O using low-temperature heat source. The experiments showed effect of the flow rates of hot water and falling film solution, temperature of heat source, concentration of the solution and generation pressure on the LiCl/H2O generation process. To compare with conventional LiBr/H2O solution, some comparative experiments of falling film generation were tested in order to discuss the mass transfer performance of two different working pairs in a high-pressure generator. The results showed that the two working pairs had similar mass transfer rate. The LiCl/H2O solution had a similar mass transfer rate to that of the LiBr/H2O solution, while the concentration of LiCl/H2O solution was much lower with smaller circulation ratio of the solution, and it could make for possible improvement in the thermal performance of the absorption refrigeration system.

Variation of pressure from cervical to distal end of oesophagus during swallowing: Study of a mathematical model

The investigation is an attempt to explore the cause that generates high pressure in the distal oesophagus compared to that in the proximal part. We observe through computer simulation that peristaltic waves of even slightly but progressively increasing amplitude can generate high pressure near the distal end. This is illustrated through exponential growth in the wave amplitude, which represents the dependence of the rate of growth of amplitude on its current magnitude. This may be physically interpreted that the generation of high pressure in the lower oesophagus ensures complete bolus delivery to the stomach through the cardiac sphincter. This finding may prove to be a very prominent result towards creating a prosthetic oesophagus. Some more conclusions with regard to progressive exponential increase in amplitude are also drawn. The pressure falls to zero invariably in the proximal half of every bolus, whereas for constant amplitude, zero pressure is located exactly at the midpoints of the boluses for Newtonian flows. Backward flow of fluid takes place in a smaller region if amplitude increases. Circular muscles contract more in the lower oesophagus to generate higher pressure in the distal oesophagus. In a sharp contrast to the case of constant-amplitude, pressure is neither uniformly distributed in a wave, nor is of identical shape for all boluses in the case of train wave propagation. Pressure distribution along the axis of the oesophagus differs in shape and magnitude both when a single wave propagates.

Ramp-Wave Compression Experiment with Direct Laser Illumination on ShenGuang-III Prototype Laser Facility**Supported by the National Natural Science Foundation of China under Grant No 11305160.

Ramp-wave compression experiment to balance the high compression pressure generation in aluminum and x-ray blanking effect in transparent window is demonstrated with an imaging velocity interferometer system for any reflector (VISAR) on ShenGuang-III prototype laser facility. The highest pressure is about 500 GPa after using the multilayer target design Al/Au/Al/LiF and 1013 W/cm2 laser pulse illuminated on the planar Al target, which generates the spatial uniformity to over 500 μm on the ablation layer. A 2-μm-thick Au layer is used to prevent the x-ray from preheating the planar ablation Al layer and window material LiF. The imaging VISAR system can be used to record the abrupt loss of the probe beam ( nm) caused by absorption and reflection of 20-μm, 30-μm and 40-μm-thick Al, i.e., the blanking effect. Although there are slight shocks in the target, the peak pressure 500 GPa, which is the highest data up to now, is obtained with ramp-wave compression.

Dynamic high pressure generation through plasma implosion driven by an intense laser pulse

When an intense laser pulse is loaded upon solids, very high impact pressure can be generated on the surface. In this letter, we simulate this process through one-dimensional particle-in-cell simulation and find that the pressure as high as 0.13 TPa can be generated after the laser pulse with intensity 1015 W/cm2 and 5 picosecond duration is injected upon a nanometer solid-density plasma. The peak pressure is shown to be resulted from an energetic high-density plasma bunch, produced through plasma implosion under extremely high light pressure.

Coke formation in pyrolysis furnaces in the petrochemical industry

ABSTRACTIn the petrochemical industry, an industrial pyrolysis furnace is a complicated piece of equipment that functions as both a reactor and high-pressure steam generator. During service, hard deposits of carbon (coke) build up on the inner wall of the tube, reducing heat transfer and restricting the flow of the hydrocarbon feedstocks. In this paper, an overview of coke formation, the impact of coke formation, and the methods by which coke formation can be prevented, as well as methods that can be successful in decoking of pyrolysis furnaces, is presented.

Numerical Analysis of Hydrodynamic Journal Bearing Lubrication using Computational Fluid Dynamics and Fluid Structure Interaction Approach

Now-a-days, journal bearings are subjected to severe loads and higher operating speeds causing generation of high hydrodynamic pressures which in turn deform the bearing shell thus modifying the lubricating film in the operating region. Hence, there is need for optimized bearing performance parameter estimation considering the realistic change in lubricating film along with less computational time. In this paper, response surface optimization module coupled with static structural and fluent, available in ANSYS workbench is used for analysing the performance of the bearing. The optimization is based on Response Surface evaluations. It has been observed that the computation time is considerably reduced. The bearing is analysed for various rotational speeds and eccentricity ratios to obtain load carrying capacity and pressure distribution. It is observed that the results are following the expected trend i.e. as speed increases the load carrying capacity as well as maximum pressure is increasing.

A constitutive framework to model the undrained loading of municipal solid waste

This paper proposes a model to represent the MSW undrained mechanical behavior, which is an extension of the previous models developed by the authors. A more comprehensive formulation for effective stress is adopted taking into account the compressibility of waste particles and the concepts embraced in the Skempton’s equation for effective stress. The model reproduces the main MSW features such as high pore water pressure generation, concave upward curves and high shear strength values, even for u=σ3 (zero net confining stress). Model predictions showed good adherence to experimental results. MSW samples of different sources were used in the simulations.

Wear Between Ring and Traveler: A Pin-On-Disc Mapping of Various Detonation Gun Sprayed Coatings

A textile mill provides one of the hardest and rigorous environments to a ring and a traveler of a spinning machine. Generation of high contact pressure between the ring and the traveler during winding led to degradation of the internal surface of the ring, thus its working life. This study elucidated towards enhancing the working life of the ring as well as decreasing the time required to reinstate the rings on the spindle periodically during spinning. The objective was carried out by comparing four different detonation gun (D-Gun) thermal sprayed coatings on bearing alloy steel (E52100) ring in a laboratory test using pin-on-disc apparatus. The microstructure and mechanical properties of the WC-Co-Cr, Cr3C2NiCr, Al2O3+TiO2 (Alumina-Titania) and Stellite-6 coatings were comparatively studied with those of uncoated E52100. The coated E52100 showed significantly less wear loss as compared to bare E52100. The investigations revealed that the cumulative volume loss for detonation sprayed coatings increased with increase in load. The WC-Co-Cr coating underwent minimum wear and the WC-Co-Cr–E52100 coating-substrate combination exhibited highest abrasive wear resistance. The results obtained during pin-on-disc laboratory test may be used for comparison of wear resistance of different coatings deposited on E52100 alloy steel rings in the textile mill.

Automatic high-pressure hydrogen generation from formic acid in the presence of nano-Pd heterogeneous catalysts at mild temperatures

First report of an automatic high pressure hydrogen generation from HCOOH with a heterogeneous catalyst system.

Performance Analysis of Heating Supply from a Coupled CCHP system with Ground Source Heat Pump

A coupled heating system with combined cooling heating and power (CCHP) system and ground source heat pump (GSHP) is proposed in this paper. The system adopts the internal combustion engine (ICE) to drive the generator to generate electricity, then the jacket water from ICE is used to absorption heat pump and/or preheats GSHP to increase the coefficient of performance (COP), and the exhausted gas is sent to the high pressure generator to drive the absorption heat pump. The mathematical models of components were established, through the analysis of the relationship between the various devices and operational characteristics. Then, the performance analysis of the system is carried out under the condition of variable jacket water distribution ratio and variable electricity load. The results show that the energy efficiency and exergy efficiency of the system are the largest, 128.24% and 34.21% at the heating work condition respectively.

Origin of abnormal high pressure and its relationship with hydrocarbon accumulation in the Dina 2 Gas Field, Kuqa Depression

AbstractBased on distribution of formation pressure by indirect estimation and formation testing, this study investigates origin of abnormal high pressure in the Dina 2 Gas Field in the Kuqa Depression in combination with the latest research findings. Contribution of major overpressure mechanisms to this gas field is estimated, and generation of the abnormal high pressure as well as its relationship with natural gas accumulation is explored. Disequilibrium compaction, tectonic stress, and overpressure transfer are the major overpressure mechanisms. Overpressure transfer resulted from vertical opening of faults and folding is the most important cause for the overpressure. Gas accumulation and abnormal high pressure generation in the reservoirs of the Dina 2 Gas Field show synchroneity. During the early oil-gas charge in the Kangcun stage, the reservoirs were generally normal pressure systems. In the Kuqa deposition stage, rapid deposition caused disequilibrium compaction and led to generation of excess pressure (approximately 5–10MPa) in the reservoirs. During the Kuqa Formation denudation stage to the Quaternary, reservoir overpressure was greatly increased to approximately 40–50MPa as a result of vertical pressure transfer by episodic fault activation, lateral overpressure transfer by folding and horizontal tectonic stress due to intense tectonic compression. The last stage was the major period of ultra-high pressure generation and gas accumulation in the Dina 2 Gas Field.

A non-singular boundary element method for modelling bubble dynamics in viscoelastic fluids

When a cavity forms near a solid boundary a liquid jet can form directed towards the boundary, causing the generation of high pressures at the wall (potentially causing damage) and the formation of a toroidal bubble. In this paper several recent developments in the boundary element modelling of the dynamics of cavitation bubbles in viscoelastic fluids are presented. The standard formulation of the boundary element method (BEM) is in terms of a boundary integral equation with a singular kernel. A reformulation of the BEM in terms of a non-singular kernel is shown to provide enhanced stability. In situations when a liquid jet forms and impacts the far side of the bubble there is a transition to a toroidal form. This topological singularity in bubble geometry is modelled by placing a vortex ring inside the bubble to account for the circulation in the fluid and the discontinuity in potential following jet impact. The bubble dynamics are dependent on the initial stand-off distance from the boundary as well as the viscous and elastic properties of the fluid. It is shown that, while the viscosity of the fluid inhibits jet formation, the dynamics are particularly dependent on the relative strength of viscous, elastic and inertial forces. In particular, if the Deborah number is large enough elastic effects effectively negate fluid viscosity and behaviour similar to the inviscid case is recovered in terms of liquid jet formation.

The fluid budget of a continental plate boundary fault: Quantification from the Alpine Fault, New Zealand

Abstract Fluids play a key role in modifying the chemical and physical properties of fault zones, which may prime them for repeated rupture by the generation of high pore fluid pressures and precipitation of commonly weak, secondary minerals. Fluid flow paths, sources and fluxes, and the permeability evolution of fault zones throughout their seismic cycles remain poorly constrained, despite their importance to understanding fault zone behaviour. Here we use geochemical tracers of fluid–rock exchange to determine budgets for meteoric, metamorphic and mantle fluids on a major compressional tectonic plate boundary. The Alpine Fault marks the transpressional Pacific–Australian plate boundary through South Island, New Zealand and appears to fail in regular ( 329 ± 68 yrs ) large earthquakes ( M w ∼ 8 ) with the most recent event in 1717 AD. Significant convergent motion has formed the Southern Alps and elevated geothermal gradients in the hangingwall, which drive crustal fluid flow. Along the Alpine Fault the Alpine Schist of the Pacific Plate is thrust over radiogenic metasedimentary rocks on the Australian plate. The absence of highly radiogenic (87Sr/86Sr > 0.7200) strontium isotope ratios of hangingwall hot springs and hydrothermal minerals formed at a range of depths in the Alpine Fault damage zone indicates that the fluid flow is restricted to the hangingwall by a cross-fault fluid flow barrier throughout the seismogenic crust. Helium isotope ratios measured in hot springs near to the Alpine Fault (0.15–0.81 R A ) indicate the fault is a crustal-scale feature that acts as a conduit for fluids from the mantle. Rock-exchanged oxygen, but meteoric water-like hydrogen isotope signatures of hydrothermal veins indicate that partially rock-exchanged meteoric fluids dominate down to the top of the brittle to ductile transition zone at ∼6 km. Geochemical tracer transport modelling suggests only ∼0.02 to 0.05% of total rainfall west of the Main Divide penetrates to depth, yet this recharge flux is sufficient to overwhelm other fluid contributions. Calculated mantle fluid fluxes of CO2 and H2O (0.2 and 3 to 13 mol/m2/yr respectively) and metamorphic H2O fluxes (4 to 750 mol/m2/yr) are considerably lower than the focused meteoric water discharge flux up the Alpine Fault (4 × 103 to 7 × 104 mol/m2/yr), driven by the >3000 m hydrologic head of the Southern Alps. Meteoric waters are primarily responsible for modifying fault zone permeability during fluid–rock interactions and may facilitate the generation of high pore fluid pressures that could assist episodic earthquake rupture.