Maximum Gas Pressure Research Articles

Feasibility analysis on the debrining for compressed air energy storage salt cavern with sediment

Using the sediment void to store gas is a promising solution for the construction of compressed air energy storage (CAES) salt cavern with high impurity. However, it remains debatable whether the pressure loss of brine in the sediment can notably affect debrining. In this paper, the in-situ sediments are obtained, and their porosity, moisture content after debrining and permeability are measured. A model of debrining in salt cavern with sediment is built. The model prediction error of injection gas pressure is less than 0.34 %. A criterion for the feasibility evaluation of debrining for CAES salt cavern with sediment is proposed. The results show that the porosity of the in-situ sediment is 47.9 %. When the sediment volume reaches 98 % of the cavern volume, the pressure loss of brine in the sediment and the maximum gas pressure are less than 3.1 MPa and 17 MPa, respectively. The sediment has good permeability, it is feasible to debrine in salt cavern with sediment. It is suggested that the debrining rate and the tubing diameter increase to more than 120 m3/h and 0.14 m, respectively. This study provides valuable guidance for the debrining in salt caverns with sediment.

Quantum physisorption behavior of methane in nanoporous shales: Model and new mechanism

Methane adsorption in nanoporous shales plays a significant role in the storage and flow of shale gas. Although previously numerous theoretical models have been proposed to describe the gas adsorption behavior, how the potential energy distribution in nanopores impacts gas adsorption remains unclear. The mechanism of methane adsorption in extremely complicated nanopores is still no satisfactory explanation. In this study, a total of 28 shale samples located in the Paleozoic-Mesozoic strata from different sedimentary environments were utilized to investigate the nature and process of quantum physisorption of methane in nanoporous shales. It was suggested that methane confined within nanoscale space shows a quantum effect, and the physisorption behavior of methane may be the result of molecular energy level transition. Further, the quantum physisorption model was developed by considering the quantum potential energy distribution, maximum adsorption amount, gas temperature and gas pressure, which matches the isothermal adsorption data well for a various of shales under widely varied temperature and gas pressure condition. The adsorption amounts of methane with different energy levels can also be obtained by the model. Finally, a new mechanism of the methane quantum physisorption in nanoporous shales was proposed. Uneven spatial distribution of gas molecules and elementary space of gas adsorption are the intrinsic factors of controlling the quantum physisorption behavior. The former is mainly influenced by minimum potential unit (E0) and gas temperature, while the latter is represented by the parameter of maximum adsorption amount (nL) which impacted by specific surface area and gas temperature. Gas pressure only affects the molecule concentration with different energy levels, but does not affect the spatial distribution of molecule. E0 and nL vary in shales from different sedimentary environments, due to the difference in organic matter properties (TOC content and kerogen type), which indirectly impacts the methane physisorption behavior. These results are helpful to deeply understand the storage of methane in shales and improve the efficient development of shale gas. In addition, this study is expected to open a new research direction about the quantum physisorption of gas in nanoporous media.

Study on Safety Tunneling Technology of Secondary Outburst Elimination by CO2 Gas Fracturing in High-Outburst Coal Seam

The No. 3 coal seam in the Yuxi Coal Mine has a measured maximum gas content of 25.59 m3/t, along with a maximum gas pressure of 2.9 MPa, indicating its high risk to gas and outbursts. To mitigate outburst risks of the coal seam, the 1301 working face has been implemented with gas pre-drainage measures by grid boreholes from underlying roadways. After one year of extraction, it was confirmed that the gas content at all 33 test sites was below 8 m3/t, meeting the outburst prevention standards. However, during subsequent coal tunnel excavation, the gas desorption index K1 value frequently exceeded the standard, resulting in numerous occurrences of abnormal gas emission or small-scale outbursts. To tackle the challenges associated with safe excavation following the first-round regional outburst prevention measures, a research and industrial trial of CO2 gas fracturing (CO2-Frac) technology for secondary outburst prevention and rapid excavation was completed. The results show that the dual-hole and high-pressure (185 MPa) CO2-Frac considerably contributes to outburst prevention. K1 exceedances per hundred meters of tunnel excavations were from an average of 2.54 without CO2-Frac to an average of 0.28 after the new technology was implemented, leading to an eight-fold reduction. Additionally, the monthly excavation footage increased from an average of 81.64 m without CO2-Frac to an average of 162.42 m with CO2-Frac, resulting in a two-fold improvement. The dual-hole and high-pressure CO2-Frac is an advanced technology for safe and efficient excavation for secondary outburst elimination in highly outburst-prone coal seams in the Yuxi Coal Mine, with potential for widespread application in similar coal seam conditions.

Thermal dynamics in deep shale reservoirs: Influences of the kerogen microstructural behavior on the gas adsorption/desorption capacity

In shale gas extraction projects, an investigation into the mechanisms of energy/mass transfer associated with shale gas adsorption/desorption in organic matter (kerogen) microstructure under high temperature and stress condition is crucial for improving the efficiency of shale gas production. This study presents a coupling thermo-hydro-mechanical model based on an improved fractal method that could explain the microstructural evolution of the kerogen system and the resultant alterations during the gas adsorption/desorption process under varying thermal conduction, gas seepage, and stress conditions. The influence of porosity, diameter, and tortuosity on the abundance, length, and complexity of kerogen networks under coupled multi-field effects is evaluated. The significance of this study is it could address the following aspects quantitively: (1) the spatiotemporal evolution of kerogen fractal dimensions following various extraction timelines; (2) the influence of shale temperatures on kerogen structures; (3) the influence of the kerogen fractal dimension on the shale gas desorption capacity and production efficiency; and (4) under different temperatures, when the fractal dimension/tortuosity fractal dimension of kerogen changes due to extraction disturbances, the volumetric deformation induced by gas adsorption increases by a maximum of 26.1%/decreases by 28.1% and in the later stages of extraction, the maximum gas pressure decreases by 44.7%/increases by 47.1%. The proposed fractal method adeptly reveals shale gas desorption behaviors under multi-field coupling conditions from a microscopic perspective, which cannot be found in the literature.

Design and Analysis of Piston by using Ansys Workbench

Abstract: In this study, structural analysis is investigated on conventional piston made of cast iron. Secondly analysis are performed on piston made of aluminum, titanium alloy , structural steel and fiber glass. The material used for the design of piston should have light weight, low cost, structurally and thermally withstand at very high pressure and temperature condition that will occur in combustion process. In this project, It has been decide to study a particular piston design And its capability for maximum gas pressure. In this work, initial planning is to make piston model using solid modeling software CATIA V5. It has been decided to mesh the geometry analyze using ANSYS. For the analysis of piston input conditions and process of analysis, a lot of literature survey has been done. High combustion gas pressure will act as a mechanical loads and causes major stresses in the critical region of the piston. Detailed static structural analysis is carried out for various loading conditions like maximum gas pressure load.

Maximum Gas Pressure in Pores

Maximum Gas Pressure in Pores

Gas-entry pressure impact on the evaluation of hydrogen migration at different scales of a deep geological disposal of radioactive waste

Although the importance of gas-entry pressure in simulating two-phase liquid–gas flow in porous media has been studied at the column and borehole scales, its impact on the simulation of transient hydraulic-gas at different scales of a deep geological repository of radioactive waste (DGR) in low permeability clay rock during the post-closure phase has not yet been studied. The purpose of this work is to show that neglecting this phenomenon can lead to underestimation of the maximum gas pressure and water–gas fluxes simulated within the host rock and backfilled drift network. This could impact the performance of the engineered barrier system of a DGR. Simulations performed for a high-level waste disposal cell and for a simplified repository composed of hundreds of disposal cells situated in a clay host rock, show that gas preferentially migrates through the DGR components with low capillary entry pressures, such as the excavation damaged zone (Refers to the zone where fractures develop due to failure of the rock mass around galleries after tunneling) (EDZ), the engineered barriers materials (backfill, bentonite-plug…) and interfaces between the EDZ and these materials. Such a result could have significant consequences on the performance of a repository, due to the accumulation of gas in the drift network and high increase of gas pressure, which could lead to the host rock hydraulic fracturing.

High sensitivity temperature and gas pressure sensor based on PDMS sealed tapered hollow-core fiber

We use hollow core fiber (HCF) and single mode fiber (SMF) fusion splicing to form a sensor with a “SMF-HCF-SMF” structure. To improve the sensitivity of the sensor, the HCF is tapered and stretched to a waist diameter of 10 μm. Then, in order to further improve the sensitivity of the sensor to temperature and pressure, as well as the mechanical strength of the sensor, we coated a layer of polydimethylsiloxane (PDMS) thin film on the surface of the tapered HCF. When light propagates in the sensor, an anti-resonant reflection optical waveguide (ARROW) mechanism is formed. Due to the excellent thermal sensitivity and elasticity of PDMS, the transmission spectrum of the sensor will significantly drift due to changes in environmental temperature and gas pressure, achieving temperature and pressure measurement. The experimental results show that the maximum temperature and gas pressure sensitivity of the sensor reach −3.2321 nm/℃ and −22.80 nm/MPa, respectively. In addition, the sensor also has good repeatability and stability, as well as short response time. It has certain application prospects in the field of high sensitivity temperature and gas pressure sensing measurement.

Highly sensitive gas pressure sensor based on the hollow core Bragg fiber and harmonic Vernier effect.

A highly sensitive inline gas pressure sensor based on the hollow core Bragg fiber (HCBF) and harmonic Vernier effect (VE) is proposed and experimentally demonstrated. By sandwiching a segment of HCBF between the lead-in single-mode fiber (SMF) and the hollow core fiber (HCF), a cascaded Fabry-Perot interferometer is produced. The lengths of the HCBF and HCF are precisely optimized and controlled to generate the VE, achieving a high sensitivity of the sensor. Meanwhile, a digital signal processing (DSP) algorithm is proposed to research the mechanism of the VE envelope, thus providing an effective way to improve the sensor's dynamic range based on calibrating the order of the dip. Theoretical simulations are investigated and matched well with the experimental results. The proposed sensor exhibits a maximum gas pressure sensitivity of 150.02 nm/MPa with a low temperature cross talk of 0.00235 MPa/ ∘C. All these advantages highlight the sensor's enormous potential for gas pressure monitoring under various extreme conditions.

ANALYSIS OF THE TIGHTNESS OF THE CONNECTION OF THE RUBBER PLUG AND THE PLASTIC PIPe

Various connecting elements, including electric-welded saddles, are used for tapping under pressure into pipelines made of polyethylene pipes. The analysis of the tightness of the connection of the nozzle of the saddle and the rubber plug designed to prevent the transported gas from entering the zone of elevated temperatures during the production of electric welding works using a builtin heater. The greatest influence on the change in the contact pressure between the seat nozzle and the plug is exerted by the ambient temperature and the connecting parts themselves during welding and, accordingly, the change in the temperature gradient of the connecting parts. Based on the results of the work, a comparative analysis of the results of theoretical calculations and calculations by the finite element method in the ANSYS software package, as well as the contact pressure of the mating surfaces and the maximum gas pressure were performed.

A bio-hydro-chemical model for gas pressure development in municipal solid waste landfills

Prediction of gas pressure development within municipal solid waste (MSW) landfills is of great importance for the stability analysis and design of gas collection systems. This study presents a fully coupled bio-hydro-chemical model for the gas pressure development in landfills. The reduction of foam on the relative gas permeability and the variation of the intrinsic permeability with degradation degree are considered. The source terms in the governing equations of two-phase flow and solute transport are chosen from the biodegradation process of MSW. Both one-step landfilling and multi-step landfilling are calculated to compare the differences. It is found that the fast hydrolysis of fresh MSW produces most of the volatile fatty acids (VFAs) and leachate within the first 2 months. During multi-step landfilling, the VFA and leachate produced from fresh MSW in the top flow downward to the bottom, leading to high gas production and high leachate saturation in the deep. Meanwhile, the high concentration of VFA reduces the surface tension of the leachate, enabling it to generate foam and further reduce gas permeability. Owing to the high gas production and low gas permeability, the excess gas pressure is easily developed in the deep layer. The maximum gas pressure of multi-step landfilling is about 2·5 times that of one-step landfilling. Case studies of the laboratory column test and in situ borehole test verify the accuracy of the model in predicting the temporal and spatial distribution of gas pressure. For the slope failure induced by high gas pressure, the evolution of shear strength and stability during a 2 year landfilling period is calculated and discussed.

Gas Pressure From the Endoscope: An Unexplored Contributor to Morbidity and Mortality?

Background It has been shown that the incidence of venous air embolism and venous carbon dioxide (CO2) embolism is high during endoscopic retrograde cholangiopancreatography (ERCP). We examined insufflating gas flow and maximum pressure produced by three types of commonly used endoscopes because we could not readily locate technical data for endoscope gas flow and maximum emitted pressure in the manufacturer's manuals. Methods We tested the Olympus GIF-Q180 used for esophagogastroduodenoscopy, the CF-Q180 used for colonoscopy, and the TJF-Q180 used for ERCP (Olympus America Inc., Center Valley, Pennsylvania). Under three different clinical gas insufflation scenarios, we measured in vitro maximum gas pressure transduced from a closed space created at the endoscope tip in a worst-case scenario analysis. Results We showed that it is readily possible to generate a pressure (>5-30 times normal central venous pressure) in the air space at the tip of all three endoscopes when insufflation is activatedand the gas egress is limited. Conclusions These findings shedadditional light on in vivo occurrences of gas embolism during gastrointestinal endoscopy. We postulate that in addition to using exclusively CO2 as the insufflating gas, the risk of gas embolism can be further diminished by regulating insufflating gas pressure at the tip of endoscopes.

SUBSTANTIATION OF THE ARRANGEMENT AND OPERATION OF THE MOZYR UNDERGROUND GAS STORAGE FACILITY

The relevance and importance of underground gas storages for the energy security of the Republic of Belarus is denoted. The types of underground gas storage facilities in operation on the territory of the republic are indicated.
 The geological conditions of the Mozyr salt massif in the area of the mine workings are given. The features of the structure of the Mozyr salt dome are considered. Information about the rock salt deposits of the Zalessky layers suitable for creating caverns is given. Mining and geological conditions are described and favorable factors of an underground gas storage creation in rock salt deposits under the conditions of the Mozyr salt dome are denoted. Information about the screening effect of the roof strata is given. Mathematical modeling was carried out and the assessment of the suitability of the existing
 salt caverns is given. During the conversion of existing and the creation of new caverns, as well as in the process of their operation (injection-storage-selection) long-term sustainability to the effects of pressures emerging has been confirmed.
 Formulas for determination the maximum gas pressure limit, the permissible maximum and minimum operating pressure as well as the required span of the cavern are given. The test pressure range for determining the tightness of the caverns is indicated. The conditions for choosing the minimum operating pressure in the cavern as well as the safety margin factor in relation to specific conditions are determined. In fact, the suitability and prospects of creating underground gas storage facilities in the salt domes of the Pripyat trough have been confirmed.

Experimental investigation of essential oils as fuel additives

Essential oils were investigated as fuel additives in this research. Origanum Acutidens is used to make essential oil. In the oil recovery process, hydro distillation was used. With the transesterification reaction, the obtained oil was converted into biofuel. In a specific proportion, biofuel was combined with reference diesel fuel. Critical oils were studied for their effect on engine efficiency and combustion parameters. A Kirlaskor four-stroke diesel engine was used to test the mixed fuel and comparison diesel fuel. Engine tests were carried out at various loads and at a steady engine rpm. As compared to diesel fuel, the mixture fuel provided 1.63 percent more effective engine power and 1.31 Nm more engine torque. The maximum gas pressure, maximum cumulative heat dissipation, maximum average gas temperature, and maximum net heat emission rates all increased dramatically when the combustion data was analyzed. The findings revealed that the critical oil-based blended fuel enhanced the combustion event in diesel engines.

Conceptual design of the MGI system for JT-60SA

Disruption mitigation is of high priority for future tokamaks like ITER and DEMO. Massive gas injection (MGI) has proven to be an effective method in medium size machines and will likely be part of future disruption mitigation systems. For further research, the large superconducting tokamak JT-60SA will be equipped with a MGI system as an experimental equipment. This system will consist of two in-vessel MGI valves, which are mounted in opposite segments of the machine, vacuum feed throughs, a gas preparation system and an industrial PLC for control. The MGI valves are a scaled version of the spring-driven valve used in ADSEX Upgrade with an internal gas reservoir of 815 cm³, a maximum mitigation gas pressure of 6.5 MPa, a closing pressure of about 2 MPa, a nozzle diameter of 28 mm and an opening time below 2 ms. CFD simulations with common gas mixtures indicate a peak flow rate of 3.8 kg/s after 1.6 ms. The valve has a size of 140 mm x 110 mm x 292 mm. The gas preparation system allows easy and reproducible mixing of two gases by using an electronic pressure controller.

Effect of CNG Engine Conversion on Performance Characteristic: A Review

The world has been experiencing a crisis of energy caused by the deterioration of scarce fossil fuel resources. The usage of fossil fuels, mainly liquid fuels is considered unsustainable due to resource depletion and the accumulation of pollutants. Natural gas has become a promising alternative fuel since it is highly abundant in the world, produces less emission, and gives similar engine performance compared to the existing liquid fuel, diesel, or gasoline. This paper presents various research regarding the engine performance characteristic of CNG. The studies reported that as compared to liquid-based fuel such as diesel oil or gasoline, CNG gives lower brake thermal efficiency (BTE) as compared to diesel fuel. However, the brake-specific fuel consumption (BSFC) of engine fueled with CNG is lower than diesel or gasoline fuel. In terms of exhaust gas temperature, CNG was always produced higher temperatures in comparison to gasoline. The maximum cylinder gas pressure of CNG was reported lower than diesel fuel operation. In general, the power produced by CNG combustion is a little bit lower than diesel fuel, this drawback of CNG fuel can be overcome by adding hydrogen fuel to CNG to increase produced power.

Machine Learning-based Classification of Combustion Events in an RCCI Engine Using Heat Release Rate Shapes

Reactivity controlled compression ignition (RCCI) mode offers high thermal efficiency and low nitrogen oxides (NOx) and soot emissions. However, high cyclic variability at low engine load and high pressure rise rates at high loads limit RCCI operation. Therefore, it is important to control the combustion event in an RCCI engines to prevent abnormal engine combustion. To this end, combustion in RCCI mode was studied by analyzing the heat release rates calculated from the in-cylinder pressure data at 798 different operating conditions. Five distinct heat release shapes are identified. These different heat release traces were characterized based on start of combustion, burn duration, combustion phasing, maximum pressure rise rate, maximum amount of heat release, maximum in-cylinder gas temperature and pressure. Both supervised and unsupervised machine learning approaches are used to classify different types of heat release rates. K-means clustering, an unsupervised algorithm, could not cluster the heat release traces distinctly. Convolution neural network (CNN) and decision trees, supervised classification algorithms, were designed to classify the heat release rates. The CNN algorithm showed 70% accuracy in predicting the shapes of heat release rates while decision tree resulted in 74.5% accuracy in predicting different heat release rate traces.

Influence of accelerating gap configuration on parameters of a forevacuum plasma-cathode source of pulsed electron beam

The research of influence of accelerating gap configuration on parameters of a forevacuum plasma-cathode source of a pulsed low-energy (up to 10 keV) large-radius electron beam is presented. An increase in cell sizes of a mesh emission electrode increases electron emission efficiency, but leads to a decrease in electric strength of an accelerating gap. Larger cell sizes of a mesh extractor provide higher electron beam current. An increase in the length of the accelerating gap first leads to an increase in the electron emission efficiency, but when optimal value is reached, a further increase in the length leads to a decrease in the emission efficiency. This optimal length of the accelerating gap is about 25 mm. However, the electron emission efficiency changes relatively small (within 15%). The dependencies of maximum emission current and maximum operating gas pressure on the length of acceleration gap is similar to the dependence for the emission efficiency, but the gap length much stronger influences on these maximum values. Moreover, the optimal length, at which maximum emission current or maximum pressure is provided, is depended on gas pressure (for current) or emission current (for pressure), accelerating voltage and pulse duration.

Design, Structural and Thermal Analysis of Piston by Using Finite Element Analysis

Abstract: In this project, it was chosen to investigate a specific piston design and its maximum gas pressure capabilities. The first aim for this project is to create a piston model using the solid modelling software CATIA V5. The geometry will be meshed and analyzed using the ANSYS software. A thorough literature search was conducted for the examination of piston input circumstances and the analytical process. High combustion gas pressures operate as mechanical loads, causing substantial strains in the piston's critical area. For various loading situations, such as maximum gas pressure load, a detailed static structural analysis is carried out. To choose the best material, a comparative research is carried out. Relative examination is never really dominated material. A cylinder is a mechanical part found in an assortment of cycles like pneumatic chambers. Responding siphons, responding motors and gas blowers. It is the upward development inside a chamber that is put away gastight by cylinder .In the auto business, it is found that the cylinder is the most fundamental part of the motor, and that it is presented to serious mechanical and warm loads. Warm burdens are initiated in the cylinder because of the exceptionally high temperature differential between the cylinder crown and the cooling displays. The cylinders are regularly built of aluminum due to its lightweight and heat conductivity. Be that as it may, as a result of its low hot strength and high development coefficient, it isn't suggested for use in high-temperature applications. The reason for a section bar or potentially an associating bar in a motor is to move power from growing gas to the barrel shaped shaft through an interfacing bar and additionally segment pole. To pack or remove the liquid put away in the chamber, the siphons turned around the capacity of the cylinder and communicate power from driving rod to it. In the initial step the primary examination of a common cylinder developed of the aluminum composite is concentrated in this exploration. The subsequent advance is to direct an investigation on a cylinder developed of Aluminum and Cast iron. Lightweight, minimal expense, primarily and thermally safe materials ought to be used in the development of pistons in the third step Validation of investigation result with contrasting the traditional material.

"On The Effect of Polluted Environment on The Gas Turbine Performance" .(Dept.M)

This work describes the effect of environmental polluted air properties (such as; temperature, relative humidity. volume fraction ratios of carbondioxide and carbon-monoxide ratio, and dust/sand particles) on the gas turbine performance. The polluted air properties are considered variable as under: i) Air temperature varying from 270 .to 330°K. ii) Air relative humidity changing from 0 to 100%,and iii) Reduction ratio in atmospheric pressure, due to the use of air filter at compressor intake, varying from 60 to 100%. The advanced BASIC Computer Programmes have been written for calculating the specific work and thermal efficiency of a gas turbine unit which works under the above conditions. The gas turbine performance values have been estimated by using various values of the maximum gas turbine inlet temperature (TIT) and pressure ratios (PR) (from 1200 to 1600° K, and from 10 to 16 respectively). Specific heats of the mixture have also been considered as a function of temperatures and fuel air ratios. The effect of environmental polluted air containing various ratios of Co, and CO2, on the gas turbine performance has also been investigated.