Gas Pressure Control Research Articles

Study on multi-stage adjust mechanism of downhole stratification control tool for natural gas hydrate multi-gas combined production gas lift

Accurate control of natural gas flow and pressure is essential to achieving multi-gas combined production of the natural gas hydrates. In this study, a downhole stratification control tool for controlling natural gas flow rate and pressure with a multi-stage throttling structure was innovatively proposed. The multi-stage throttling structure combined an adjustable cage sleeve and a fixed nozzle. The numerical model of the internal flow field of the downhole stratification control tool was established. Through the computer fluid dynamics numerical simulation, the flow field change law inside the spool module of the downhole stratification control tool under different spool structures, different outlet pressures, and different spool openings was analyzed. Moreover, the spool module prototype was processed, and the indoor experiment of the spool's performance of reducing pressure and regulating production was carried out. The results show that the multi-stage throttling structure has the advantages of adjustable spool opening and moderate cooling range and the mass flow of gas inside the spool changes linearly with the opening of the spool. The spool module can accurately control the mass flow of natural gas under high-pressure conditions, and meet the needs of the downhole stratification control tool for accurate gas control.

In Situ Pulsed Hydrogen Implantation in Atom Probe Tomography.

The investigation of hydrogen in atom probe tomography appears as a relevant challenge due to its low mass, high diffusion coefficient, and presence as a residual gas in vacuum chambers, resulting in multiple complications for atom probe studies. Different solutions were proposed in the literature like ex situ charging coupled with cryotransfer or H charging at high temperature in a separate chamber. Nevertheless, these solutions often faced challenges due to the complex control of specimen temperature during hydrogen charging and subsequent analysis. In this paper, we propose an alternative route for in situ H charging in atom probe derived from a method developed in field ion microscopy. By applying negative voltage nanosecond pulse on the specimen in an atom probe chamber under a low pressure of H2, it is demonstrated that a high dose of H can be implanted in the range 2-20 nm beneath the specimen surface. An atom probe chamber was modified to enable direct negative pulse application with controlled gas pressure, pulse repetition rate, and pulse amplitude. Through electrodynamical simulations, we show that the implantation energy falls within the range 100-1,000 eV and a theoretical depth of implantation was predicted and compared to experiments.

Submillisecond in situ X-ray diffraction measurement system with changing temperature and pressure using diamond anvil cells at BL10XU/SPring-8.

Recently, there has been a high demand for elucidating kinetics and visualizing reaction processes under extreme dynamic conditions, such as chemical reactions under meteorite impact conditions, structural changes under nonequilibrium conditions, and in situ observations of dynamic changes. To accelerate material science studies and Earth science fields under dynamic conditions, a submillisecond in situ X-ray diffraction measurement system has been developed using a diamond anvil cell to observe reaction processes under rapidly changing pressure and temperature conditions replicating extreme dynamic conditions. The development and measurements were performed at the high-pressure beamline BL10XU/SPring-8 by synchronizing a high-speed hybrid pixel array detector, laser heating and temperature measurement system, and gas-pressure control system that enables remote and rapid pressure changes using the diamond anvil cell. The synchronized system enabled momentary heating and rapid cooling experiments up to 5000 K via laser heating as well as the visualization of structural changes in high-pressure samples under extreme dynamic conditions during high-speed pressure changes.

Gas pressure, in-situ stress and coal strength effects on the evolution process of coal and gas outbursts based on the experimental data

ABSTRACT This paper investigated the effects of gas pressure, in-situ stress, and coal strength on coal and gas outbursts (CGO) based on the laboratory CGO experimental data. Based on the hypothesis of the comprehensive of CGO, the single-factor control variable method was used to analyze and evaluate the relative outburst intensity, the characteristics of outburst holes, the distribution of pulverized coal, the drops of outburst gas pressure, and the pulverized coal density under different outbursts experimental condition. The improved CGO energy equation and instability criterion are proposed as a direction to study the occurrence of CGO as an energy evolution direction. Furthermore, the results shows that the initial outburst gas pressure was 0.45 MPa during the experimental conditions of in-situ stress was 5 MPa, and the coal strength was 0.24 MPa. The gas pressure is directly proportional to the relative outburst intensity, while the in-situ stress and coal strength are inversely proportional to the relative outburst intensity. After the CGO occurred, the outburst coal always show spallation and pulverization characteristics. The results highlight that the gas pressure plays a key role in pulverizing and throwing out the pulverized coal, and the in-situ stress mainly plays a role in destroying the coal, and the coal strength plays a resistance role during the CGO occurs. It is also found that pulverized coal particles size less than 0.28 mm can be used to represent the distribution pattern of the total weight of outburst pulverized coal particles in the different outburst interval. These results clearly illustrate that using effective methods to control gas pressure, in-situ stress, and coal strength has an important role in preventing and controlling CGO on coal mining sites.

Scanning SQUID-on-tip microscope in a top-loading cryogen-free dilution refrigerator.

The scanning superconducting quantum interference device (SQUID) fabricated on the tip of a sharp quartz pipette (SQUID-on-tip) has emerged as a versatile tool for the nanoscale imaging of magnetic, thermal, and transport properties of microscopic devices of quantum materials. We present the design and performance of a scanning SQUID-on-tip microscope in a top-loading probe of a cryogen-free dilution refrigerator. The microscope is enclosed in a custom-made vacuum-tight cell mounted at the bottom of the probe and is suspended by springs to suppress vibrations caused by the pulse tube cryocooler. Two capillaries allow for the in situ control of helium exchange gas pressure in the cell that is required for thermal imaging. A nanoscale heater is used to create local temperature gradients in the sample, which enables quantitative characterization of relative vibrations between the tip and the sample. The spectrum of the vibrations shows distinct resonant peaks with a maximal power density of about 27 nm/Hz1/2 in the in-plane direction. The performance of the SQUID-on-tip microscope is demonstrated by magnetic imaging of the MnBi2Te4 magnetic topological insulator, magnetization and current distribution imaging in a SrRuO3 ferromagnetic oxide thin film, and thermal imaging of dissipation in graphene.

밀폐형 공압회로 내 정밀압력제어를 위한 기계 구동식 가스 압력제어기의 제어특성 평가

In this work, precise gas pressure control based on a closed pneumatic circuit was achieved with a mechanically driven gas pressure controller (MDGPC), consisting of a variable-volume bellows chamber and linear actuator. The linear actuator was employed to change an axial dimension of the bellows chamber with the proportional (P) and proportional-integral (PI) controls for fast, stable, and precise pressure control of the gas inside the bellows chamber. The pressure control stability and resolution of the MDGPC were approximately 1.5 Pa and 10 Pa for the P control and 1 Pa and 5 Pa for the PI control, respectively. Despite the more stable and precise control characteristics of the PI control method, overshoots and undershoots observed during the set-point pressure changes and recoveries from pressure disturbances rendered it unsuitable for the MDGPC control method. In contrast, the MDGPC operated under the P control did not show any significant overshoots or undershoots when the set-point pressure abruptly changed or when the MDGPC was exposed to pressure disturbances. Therefore, it was concluded that a fast, precise, and stable gas pressure control in a closed manner was attainable with the MDGPC under the P control.

Influences of key design parameters to operating performance of a compressed natural gas injection system using solenoid pressure regulator

A study is carried out to examine the effects of design parameters on operating performance of a compressed natural gas (CNG) injection system. This system consists of a solenoid-type injector, a solenoid pressure regulator, and a rail tube. To depict the operation of the injection system, mathematical models are built, including electrical and mechanical models of a solenoid pressure regulator and a solenoid injector. To control rail tube gas pressure, a control model is built using proportional integral derivative (PID) algorithm. The simulated gas pressure is compared with experimental result for validating the mathematical models. The influences of design parameters, including rail tube volume, stiffness of spring, and number of coil turns in the solenoid pressure regulator, on the operating performance of the CNG system are examined. The simulation results indicate that the stability of controlled gas pressure is increased when increasing the volume of the rail tube and spring stiffness. Besides, by decreasing the number of coil turns in the solenoid pressure regulator, the stability of controlled gas pressure and flow rate of the injection is increased.

Large area planar UV–Visible photodetectors using wide bandgap WO3−δ films

A simple synthesis technique of semiconducting monoclinic phase tungsten oxide (WO3−δ) films is demonstrated. In this article, we report the effect of oxidation temperature on oxygen vacancy gradient of WO3 films and their photo sensing properties. The WO3−δ films were grown on Si/SiO2 substrates by argon ion-beam sputtering of a high purity W (tungsten) target followed by thermal oxidization in the tubular furnace at three different oxidation temperatures at 500, 600 and 700 °C with controlled oxygen gas pressure. Detailed crystal structure, microscopic and spectroscopic characterizations reveal that the oxidation at temperature 700 °C produces reasonably good crystalline quality of the film exhibiting UV–Visible photo sensing properties. The effect of oxidation temperature towards an enhancement in crystallinity which in turn gives rise to sharp Raman peak is discussed. The fabricated device exhibits a very low dark current of 7.5 × 10 −8 A at ±0.5 V bias for WO3−δ films oxidized at 700 °C. The photodetection measurements show linear current-voltage (I–V) behaviour with light-to-dark current (ILight/IDark) ratio ∼102 at 365 nm illumination (∼0.82 mW cm−2) at 2 V applied bias. The responsivity (Rλ), specific detectivity (D*) and external quantum efficiency (EQE) were found to be ∼0.12 AW−1, ∼2.1 × 1010 Jones (cm Hz1/2 W−1) and 40%, respectively, at 365 nm illumination (∼0.82 mW cm−2) with an applied bias of 2 V for the films oxidized at 700 °C. While upon visible light illuminations, the Rλ, D* and EQE were calculated to be ∼0.78 AW−1, ∼1.4 × 1011 Jones and 174%, respectively, upon 555 nm illumination (∼0.21 mW cm−2), with 2 V applied bias. A faster photocurrent relaxation time was observed from the films oxidized at 700 °C. The ultraviolet photoelectron spectroscopy study shows a surface band gap of 3.7 eV with absolutely no density of states in the near Fermi-level, validating fully stoichiometric surface. The effects of oxidation temperatures causing the large bandgap are discussed in terms of the device performances.

Closed-type pneumatic temperature control of a pressure-controlled loop heat pipe with a mechanically driven gas pressure controller

Precise and rapid temperature controls without overshooting or undershooting are of prime importance in numerous industrial and scientific applications. The recently-suggested pneumatic temperature control technique with a pressure-controlled loop heat pipe (PCLHP) was considered to be a fit-for-purpose method achieving those required features despite its open nature caused by use of an open-type commercial gas pressure controller. In this work, a closed-type pneumatic temperature control method was established based on the PCLHP equipped with a mechanically driven gas pressure controller (MDGPC). The MDGPC comprised a variable-volume bellows chamber and a linear actuator, and gas pressure control was realized by varying the axial dimension of the bellows chamber. The MDGPC attained a pressure control stability and resolution of approximately 1 Pa and 10 Pa, respectively. Rapid and stable recovery from sudden external pressure disturbances was demonstrated, and stepwise pressure changes of ±5 kPa were successfully achieved with a stability of approximately 1 Pa without any instabilities. With the MDGPC, pneumatic temperature control of the PCLHP was realized in a closed manner; the stability of the pneumatically controlled temperature was approximately 0.01 °C, which is comparable to the stability obtained with a commercial open-type gas pressure controller. Temperature steps of approximately 0.8 °C were generated via pressure steps of ±2.5 kPa, and the change in temperature was accurately predicted with a thermodynamic relationship. Wide-range and stable temperature changes were also attained under gradual pressure changes generated by the MDGPC. Overall, closed-type pneumatic temperature control of the PCLHP was successfully realized with the MDGPC.

Hunting dark energy with pressure-dependent photon-photon scattering

Toward understanding of dark energy, we propose a novel method to directly produce a chameleon particle and force its decay under controlled gas pressure in a laboratory-based experiment. Chameleon gravity, characterized by its varying mass depending on its environment, could be a source of dark energy, which is predicted in modified gravity. A remarkable finding is a correspondence between the varying mass and a characteristic pressure dependence of a stimulated photon-photon scattering rate in a dilute gas surrounding a focused photon-beam spot. By observing a steep pressure dependence in the scattering rate, we can directly extract the characteristic feature of the chameleon mechanism. As a benchmark model of modified gravity consistent with the present cosmological observations, a reduced $F(R)$ gravity is introduced in the laboratory scale. We then demonstrate that the proposed method indeed enables a wide-ranging parameter scan of such a chameleon model with the varying mass around $(0.1\ensuremath{-}1)\text{ }\text{ }(\ensuremath{\mu}\mathrm{eV})$ by controlling pressure values.

Predictive analytics for fault reasoning in gas flow control facility: A hybrid fuzzy theory and expert system approach

Gas pressure reduction stations are essential in energy distribution networks because even a minor failure of these systems causes disruptive consumer problems. This study aims to introduce and implement a new knowledge-based platform that uses the synthesized expert's opinions to improve gas pressure control facilities. Given the record of failure of gas transmission system components and the data's uncertain nature, a new fuzzy expert system is developed that takes advantage of the object-oriented programming paradigm to analyze failure modes and conditions. The artificial intelligent model is designed in C# programming language, and a user-friendly interface is developed for ease of implementation. The knowledge-based model's validity has been tested by implementing real-world case studies adapted from the Iranian gas industry. Implementing the designed expert system shows that it can minimize the probability of a breakdown and improve safety conditions.

Study on SPF/DB Technology for Two-Sheet Hollow Structure of 1420 Al-Li Alloy

The two-sheet hollow structure of the 1420 Al-Li alloy was prepared by the method of superplastic forming and diffusion bonding. The interface combination status of the diffusion bonding region and the microstructure of the superplastic forming region were observed by an optical microscope. The thickness distribution of the superplastic forming region was measured by an ultrasonic thickness meter machine, the defect detection was tested by X-ray nondestructive inspection, and the failure modes of the samples were analyzed. The results showed that the two-sheet hollow structure of the 1420 Al-Li alloy was prepared successfully, the structure was integrated, and there were no shape defects such as pit, wrinkle, and collapse. The structure shape was almost attached to the die completely, and the thickness was almost uniform distribution. The no deforming area of the two-sheet hollow structure of the 1420 Al-Li alloy was a long strip, rolled microstructure, while the grains near the round corner area were equiaxed states resulting from dynamic recrystallization. The improper control of the superplastic gas pressure in the forming process would lead to the tearing or the die-attaching failure for the two-sheet hollow structure of the 1420 Al-Li alloy.

Integration of Hot Tube Gas Forming and Die Quenching of Ultra-High Strength Steel Hollow Parts Using Low Pressure Sealed-Air.

A low pressure sealed-air hot tube gas forming process of ultra-high strength steel tubes was developed not only to change the cross-section of the hollow products by bulging but also to increase the strength of components. Gas-formed components are typically formed by a controlled-gas pressure with extremely high internal pressure, which leads to affected production costs and safety. Moreover, compressing the gas with high pressure requires high energy during its preparation. Therefore, to simplify the internal pressure controlling system and improve the safety factor in gas forming processes, the sealed-air tubes are formed with a quite low initial pressure. The pressure of the sealed air increased with increasing temperature of the air inside the resistance-heated tube, and the bulging deformation was controlled only by axial feeding. The effects of the initial pressure and heating temperature on the bulging deformation and quenchability of the tubes, and the effect of the starting time of axial feeding on the bulging behavior were examined. Consequently, ultra-high strength steel bulged parts were produced even in low initial internal pressure and with the rapid heating of the tubes.

Hollow-Core Fiber HBr Laser with 4.3 μm Single Spectral Line Based on Gas Pressure Control

Hollow-Core Fiber HBr Laser with 4.3 μm Single Spectral Line Based on Gas Pressure Control

Effects of working conditions on the operating characteristics of an injection system applied on CNG fueled vehicles

A model-based study is conducted to examine the operating characteristics of an injection system applied on CNG fueled vehicles. This injection system is a combination of an electric pressure regulator, a rail tube, and a solenoid injector. The electric pressure regulator has a great potential to be widely used in injection systems of natural gas-fueled engines due to its flexible operation, which can help to improve the engine performance and reduce emission. This paper presents a simulation study using mathematical models to describe and analyze the operating characteristics of the gaseous fuel injection system, in which models of electric pressure regulator, solenoid fuel injector, and control model for electric pressure regulator are presented. The simulation results are compared with experimental data to validate the simulation models. Effects of working conditions, including coil resistance of the electric pressure regulator, inlet gas pressure, and set pressure in the rail tube, on the operating characteristics of the gaseous fuel injection system are investigated. Simulation results show that when the coil resistance of the electric pressure regulator is increased from 3.1 Ω to 4.1 Ω, the maximum fluctuation of the controlled gas pressure in the rail tube is reduced from 0.017 to 0.012 MPa, respectively. By decreasing the inlet gas pressure of the electric pressure regulator from 2.5 to 2.3 MPa, the controlled gas pressure in the rail tube is more stable with the maximum fluctuation significantly reduced from 0.012 to 0.002 MPa, respectively, which leads to stability in injection flow rate. The increase of set pressure in the rail tube from 0.5 to 0.7 MPa can help to improve the stability of the controlled gas pressure in the rail tube with the maximum fluctuation respectively reduced from 0.002 to 0.001 MPa.

A multi-purpose high-pressure and high temperature gas-flow cell for operando optical Raman spectroscopy.

A multi-purpose in operando optical cell with temperature and gas pressure control is described. This device allows for in operando Raman spectroscopy measurements for different applications. Its original designincludes a temperature control from room temperature up to 1000°C and a heating stage that provides uniform and stable thermal conditions. The pressure control of the cell ranges from 10-1Pa to 6 MPa, and it is compatible with different gases. Both oxidizing and reducing gases are allowed to pass through the sample surface under study. The device has been calibrated and applied to collect Raman spectra for different reaction systems under various operating temperatures and pressures.

Gas pressure control of electric arc synthesis of composite Sn–SnO2–C nanomaterials

It was found that the variation of a buffer gas pressure in the reactor chamber can control the structure of the synthesized materials during electric arc sputtering of composite Sn–C electrodes. The gas dynamic model calculated by the direct simulation Monte Carlo method shows that the buffer gas pressure affects the local parameters of tin and carbon vapor condensation. As a result, Core-shell Sn–SnO2 nanoparticles packed in a carbon matrix with various structural properties have been synthesized. It has been found that an increase in the buffer gas pressure leads both to an increase in the average size of the synthesized nanoparticles and to the formation of a more disordered structure of carbon. In turn, the tin and carbon structure affects the electrochemical characteristics of the synthesized Sn–C composite as anode materials for lithium-ion batteries.

Development of high-speed capillary spinner cell for in situ powder diffraction under gas pressure control

Development of high-speed capillary spinner cell for <i>in situ</i> powder diffraction under gas pressure control

Optimization of Gas Pressure Control of Fuel System Based on IPSO-BP Algorithm

Optimization of Gas Pressure Control of Fuel System Based on IPSO-BP Algorithm

Fractional-differential approach to describe the process of feeding metals and alloys solidifying under controlled gas pressure

To describe the processes of filtration in the folding dendritic-porous middle of the proponation, a number of fractional-differential mathematical models of the diffusion type. Described non-linear, how to take the shot of the abducted Riman-Leeuwill for an hour, as it can be stuck for a correct description of the single-phase filtration of not Newtonian age in the porous middle.The two-phase zone, which is established during the transition from melting from hard to hard mill, can often be characterized by abnormal kinetics of resistance. The peculiarities of kinetics in the whole range of winners are related to the issues of widespread nonlocality, in a number of types, memory defects, which adhere to the progressive laws. The mathe-?atical apparatus, which allows to adequately describe such processes, is the theory of integration-differentiation of the fractional order.Victorians in robotic thinking have a phenomenological character, so the possibility of their dependence in a specific, practical dermal condition is blamed on the basis of experimental results, so that the validity of other differences is confirmed. Stagnation of the given approach for describing the dynamics of the process of vitality of the two-phase zones and metals and alloys, which solidifies in the minds of a regulated gas vice. Presented in the fractional-differential robotic model of filtration are classified as abnormal diffusion. A characteristic feature of the ryvnyan, which is derived from different types of differential models of filtration, is not the same. With a whole model, they preserve the structure of the classical lines of filtration in the whole order and pass into them in boundary drops, if the order of the other differentiation is old.Vivchennya yakіsnyh authorities otrimanih іvnyans, and also prompts їh numerical decisions є to finish nontrivial zavdannyi, as vimagayut in the skin okremomu vampad of independent thought.