Values Of Gas Pressure Research Articles

Evaluation of the Possible Effects of Varying the Volumetric Ratio of Lpg on the Spark Ignition Engine's Performance, Emissions, and Combustion

This study investigated the performance, emission reactions, and combustion of liquefied petroleum gas (LPG) at various volumetric ratios with gasoline. The experiments were carried out on a single cylinder spark ignition (SI) engine at different engine loads (500 to 3000 W). In general, the use of LPG has a negative effect on performance and combustion, while making a positive contribution to emissions. The brake thermal efficiency (BTE) and brake specific fuel consumption (BSFC) values closest to 100% gasoline were obtained with 25% LPG and were lower by 0.36% and 4.55%, respectively. Conversely, using LPG resulted in lower emissions of carbon dioxide (CO2), hydrocarbons (HC), and carbon monoxide (CO). The lowest emissions were obtained with the use of 100% LPG as 0.5%, 65 ppm and 9.5%, respectively. Compared to 100% gasoline, 20.63%, 27.78% and 5.19% improvements were achieved. Finally, the cylinder gas pressure value was negatively affected using LPG. Compared to 100% gasoline, the gas pressure value obtained with 75% LPG content fuel was 7.81% lower. It has been concluded that LPG is an environmentally friendly alternative fuel in terms of emissions, and considering the decrease in performance values, 25% LPG can be used successfully in SI engines instead of 100% LPG.

Effect of three alkaline impurities on the pressure of 1,2, 4-triazole pyrolysis gas

1,2,4-triazole is now widely used in the production of pesticides and medicine, and progress has been made in the application of materials. The structural characteristics of 1,2,4-triazole with high nitrogen content will cause it to the release of a large amount of gas when it occurs pyrolysis, which may have a certain impact on industrial production safety. In the industrial process, there will be some other impurities mixed into it, so the influence of these impurities on the 1,2,4-triazole pyrolysis gas is worth exploring. In this study, the adiabatic acceleration calorimeter was used to simulate the adiabatic conditions to study the pressure value of the gas generated by the pyrolysis of 1,2,4-triazole itself, and the influence of the addition of three basic impurities on the overall pyrolysis pressure value. Experiments show that these three impurities can affect the pressure value of pyrolysis gas in different degrees. The results can provide reference for the loss prevention and control of 1,2,4-triazole in industrial production.

Spontaneous convective pattern formation in a dusty plasma

We report on experimental observations of self-sustaining convective patterns in a dusty plasma system. The experiments are carried out in a capacitively coupled radio frequency (RF) argon plasma discharge in which a dusty plasma is produced by introducing micrometer-sized melamine formaldehyde particles. A self-sustained pair of convective cells with opposite vorticities is seen to appear in a lateral view of the system, beyond some threshold values of the background gas pressure and RF power. Particle tracking velocimetry measurements reveal the existence of a dust temperature gradient that is responsible for the convective counter-rotating patterns. The origin of the kinetic temperature gradient in the absence of any external heat source is attributed to the larger ion flux induced heating of the bottom layer of the dust cloud. The velocity and vorticity of the particles in the convective cell increase with an increase in the vertical kinetic temperature gradient. The experimental results compare reasonably well with the findings of molecular dynamics simulations of the laboratory system.

Harnessing NOx emission management: A virtual sensor model for natural gas power generation engines with active pre-chamber

This paper presents a NOx Sensor machine learning model for a highly efficient 2MW power generation lean burn gas engine with an active pre-chamber. As gas power generation continues to evolve, engine efficiency and the accurate measurement of NOx emissions has taken on greater importance. However, the working life of existing NOx sensors pales in comparison to the lifecycle of an engine. This paper studies a series of machine learning NOx sensor models and carries out a comparative analysis. We introduce a predictive analytics model used for monitoring the emissions of active pre-chamber gas engines. This real deployment aims to detect the deviations in emissions across an entire fleet of gas engines, even when no physical sensors are installed in the engines. Finally, a model has been implemented that allows the prediction of NOx values, in engines that did not have them initially, with a 5–10 % precision. For example, with NOx at 120 ppm, the virtual sensor provides values close to +-10 ppm. It has been observed that such features as the setpoint value of the active pre-chamber gas pressure, in a lean burn gas engine with active pre-chamber, are among those parameters that have the greatest impact on the model estimation.

Determining the effect of laboratory testing conditions on working parameters of the ST-25 hall thruster

The object of this study is the ST-25 Hall thruster with limited discharge power, no more than 200 W, designed by Flight Control LLC (Ukraine). The problem that was solved in the current paper was to determine the effect of residual gas pressure in vacuum chambers on the operating parameters of the Hall thruster. To solve this task, the operating parameters of the ST-25 thruster were determined, which was tested in three vacuum chambers with different sizes of residual pressure. As a result of the laboratory study into the operating parameters of the ST-25 thruster, the volt-ampere characteristics of the engine discharge at fixed values of the working gas (xenon) flow rate were obtained. The dependences of the engine thrust on the mass flow rate of the working gas at fixed values of the discharge voltage were derived. Based on the experimental data, the dependences of the specific impulse of the engine anode unit on the discharge voltage, as well as the dependence of efficiency of the engine anode unit on the discharge voltage were calculated. The studies showed that when the residual pressure in the vacuum chamber is reduced by 2–3 times, the operating parameters of the engine increase by 15–20 %. Such a reduction in residual pressure increases thrust by 25–40 %. Special feature of the results is the determination of threshold values of residual gas pressure in vacuum chambers during experimental studies, in which the operating parameters of the Hall thruster are similar to its operating parameters under space conditions. This work’s findings could be used in practice when conducting experimental studies of electric rocket engines, when it is necessary to estimate the operating parameters of Hall thrusters that will be obtained under actual space conditions

Pressure Behaviour of Hot Gases and Smoke in Fires of Large Enclosures with Different Ventilation Systems

This study investigates numerically the pressure behavior of hot gases and smoke in fires of large enclosures. It mainly covers the effectiveness of using natural and mechanical ventilation in changing the pressure behaviour of hot gases and smoke inside different structures. Fire Dynamics Simulator (FDS), provided by NIST, has been used to run the simulations for all proposed cases. For the assumed scenarios, the values of hot gas pressure and temperature are extracted at different points, especially in the hot layer close to the ceiling, for further analysis. The effect of changing the location of the fire source has been investigated, too. Final results show noticeable changes in the behavior of pressure, and temperature, in the presence of different ventilation systems, both natural and mechanical. Thus, appropriate ventilation systems can improve the pressure behaviour inside the place, which offers a better environment and higher safety level, in case of fire, in such large enclosures, open plan offices,

Dynamic Measurement and Prediction of Sulfur Hexafluoride Gas Weight Based on Non-Ideal Gas State Equation and Improved Random Forest

Real-time knowledge of sulfur hexafluoride (SF6) gas weight can effectively manage and maintain the power equipment using SF6. Firstly, the gas pressure and temperature sensors are utilized to measure SF6 gas pressure and temperature dynamically. Secondly, the measured gas pressure and temperature values are converted to the SF6 gas weight using equations for calculating non-ideal gas states. Finally, the dynamic prediction model of the SF6 gas weight is developed by combining the improved chimp optimization algorithm and random forest algorithm. The dynamic prediction model is trained using measured pressure and temperature data as inputs and the calculated SF6 gas weight as outputs. The trained prediction model enables the dynamic prediction of SF6 gas weight. The experimental results show that the mean absolute error, root mean square error, and mean absolute percentage error of the proposed prediction model reaches 51.54 kg, 103.59 kg, and 11.62%.

Advective gas flow in bentonite: Development and comparison of enhanced multi-phase numerical approaches

Understanding the impact of repository gas, generated from degradation of waste and its interaction with the host rock, is essential when assessing the performance and safety function of long-term disposal systems for radioactive waste. Numerical models based on conventional multi-phase flow theory have historically been applied to predict the outcome and impact of gas flow on different repository components. However, they remain unable to describe the full complexity of the physical processes observed in water-saturated experiments (e.g., creation of dilatant pathways) and thus, the development of novel representations for their description is required when assessing fully saturated clay-based systems. This was the primary focus of Task A within the international cooperative project DECOVALEX-2019 (D-2019) and refinement of these approaches is the primary focus of this study (Task B in the current phase of DECOVALEX-2023).This paper summarises development of enhanced numerical representations of key processes and compares the performance of each model against high-quality laboratory test data. Experimental data reveals that gas percolation in water-saturated compacted bentonite is characterised by four key features: (i) a quiescence phase, followed by (ii) the gas breakthrough, which leads to a (iii) peak value, which is then followed by (iv) a negative decay. Three models based on the multiphase flow theory have been developed. These models can provide good initial values and reasonable responses for gas breakthrough (although some of them still predict a too-smooth response). Peak gas pressure values are in general reasonably well captured, although maximum radial stress differences are observed at 48 mm from the base of the sample. Here, numerical peak values of 12.8 MPa are predicted, whereas experimental values are about 11 MPa. These models are also capable of providing a reasonable representation of the negative pressure decay following peak pressure. However, other key specific features (such as the timing of gas breakthrough) still require a better representation. The model simulations and their comparison with experimental data show that these models need to be further improved with respect to model parameter calibration, the numerical representation of spatial heterogeneities in material properties and flow localisation, and the upscaling of the related physical processes and parameters. To further understand gas flow localisation, a new conceptual model has been developed, which shows that discrete channels can possibly be induced through the instability of gas-bentonite interface during gas injection, thus providing a new perspective for modeling gas percolation in low-permeability deformable media.

AERONOMIC MODEL OF HYDROGEN-HELIUM UPPER ATMOSPHERES OF HOT GIANT EXOPLANETS

The paper presents 1D aeronomic model of hydrogen-helium upper atmospheres of hot giant exoplanets based on the approximation of single-fluid multicomponent hydrodynamics. Chemical reactions and heating-cooling processes are taken into account. Typical hot Jupiter and warm Neptune are considered as an example of the application of the model. Calculations were carried out for various values of gas pressure at the photometric radius of the planet. In the solutions obtained, a transonic planetary wind is formed, leading to a hydrodynamic outflow of the atmosphere with mass loss rates of the order of \(3.5 \times {{10}^{{10}}}\) g/s for hot Jupiter and \(3.7 \times {{10}^{9}}\) g/s for warm Neptune. At the same time, the outer layers of the atmosphere of hot Jupiter are completely ionized, while the atmosphere of warm Neptune mainly consists of neutral gas. In some variants of the hot Jupiter model, instability develops in the deep layers of the atmosphere, which can lead to the formation of a specific cloud layer.

Hydrodynamic cumulation mechanism caused by quantum shell effects.

The computational and theoretical analysis carried out in this article demonstrates the existence of a nontrivial mechanism for the compression of a submicron-sized gas bubble formed by a gas of classical ions and a gas of degenerate electrons. This mechanism fundamentally differs from conventional compression mechanisms. It is shown that taking into account the quantum effect of a large spatial scale in the distribution of electrons qualitatively changes the character of cumulative processes. Because of a large-scale electric field caused by quantum shell effects, the compression process is characterized by the formation of multiple shock waves. The values of gas temperature and pressure achieved during compression occur higher by two orders of magnitude as compared with the classical adiabatic regime. The analysis is carried out within the framework of the following model: the dynamics of the electron subsystem is described by equations of a quantum electron fluid, while the hydrodynamic approximation is adopted for the ionic subsystem. The large-scale effect is taken into account by means of effective external field acting on electrons. The theoretical analysis carried out within this approach clarifies the nature of the cumulative process in the system under consideration; some quantitative characteristics obtained with numerical simulation are presented. The possibility of experimental observation of this cumulative mechanism is analyzed. It is suggested that the manifestation of the effect can be observed during laser compression of a system of submicron targets by measuring the neutron yield.

Internet of things with NodeMCU ESP8266 for MPX-5700AP sensor-based LPG pressure monitoring

The use of liquefied petroleum gas (LPG) cylinders as fuel has become a basic need for the community. LPG is more efficient than oil stoves, but LPG also poses a danger. The dangers contained in gas cylinders cause users to be afraid to check the availability of gas in cylinders because the checking process must be directly close to the gas cylinder. Because of this danger, users do not check gas availability, causing it to run out of gas when cooking. To solve this problem, a system is needed to detect the availability of LPG contents, which can be monitored remotely so that users will feel safe because they are not close to gas cylinders. The condition of gas cylinder availability can be remotely monitored using the internet of things (IoT) method. Therefore, an IoT-based LPG pressure monitoring tool was designed. A tool designed using the MPX-5700AP sensor is useful for detecting gas pressure values in LPG cylinders. IoT is used to monitor LPG pressure using the Blynk application. The buzzer module is a tool for sending sound signals as information on the condition of gas cylinders. The NodeMCU ESP8266 microcontroller processes and sends data to the Blynk application. System testing is carried out in three conditions: full, close to empty, and empty. The results of this test showed an error value of 3.41% and an accuracy rate of 96.59%.

Experimental investigation on microhardness, surface roughness, and white layer thickness of dry EDM

In this research, the environment-friendly dry electrical discharge machining (EDM) process is investigated to improve the microhardness, surface finish, and white layer thickness of the machined surfaces using graphite-argon gas as a dielectric medium. The graphite powder, mixed with compressed argon gas, has been used to replace the existing dielectric medium in the EDM process. Gas pressure, discharge current, pulse width, and gap voltage were working as input parameters to reduce surface roughness and enhance the microhardness and white layer thickness. The Taguchi L16 orthogonal array is applied to the design and analysis of the experimental results. The minimum surface roughness (2.23 μm) of the HN31 steel has been attained by increasing the gas pressure up to 1.0 MPa and the minimum values of pulse width (40 μs), gap voltage (40 V), and discharge current (6 A). The maximum microhardness (501.04 HV) has been obtained at 1.2 MPa of gas pressure, 120 μs of pulse width, 60 V of gap voltage, and 18 A of discharge current. The maximum white layer thickness (16.24 μm) is achieved by the maximum values of gas pressure (1.2 MPa), pulse width (160 μs), gap voltage (70 V) and discharge current (18 A). The SEM analysis had been done to reveal the white recast layer thickness and surface roughness of the machined surfaces of the dry EDM process. The SR is increased by the recast layer, pores, and microcracks on the machined surfaces. Finally, the multi-criteria optimization technique: Weight Product Method (WPM) is applied to predict optimum process parameter settings: GP: 1.2 MPa, PW: 120 μs, GV: 50 V, and DC: 18 A to meet the best machining performances (MH = 493.32 HV, WLT = 14.28 μm, and SR = 3.82 μm). The validation tests were done to confirm the predicted results obtained by both the Taguchi and WSM methods.

Rheological Properties of Wheat Flour when Mixed with Barley Flour

Some chemical and rheological properties of local barley varieties were investigated. Overall, the moisture, protein, fat, ash, and fiber content of the barley flour was higher than that of wheat flour. Different varieties of composite flour were created by partially substituting 10%, 15%, and 20% barley flour for wheat flour. This increased the arrival time to line 500. B.U. maturity time and critical kneading coefficient measured by Farinograph device, and the increase in fermentation gas pressure values measured by fermentation pressure gauge for dough of compound flour with different replacement ratios. As shown the amylograph results reveal that a drop in the temperature of the beginning of gelatinization of the composite flour solution and the rates of maximum viscosity of the composite flour, the rates of the flour water absorption, period of stability measured by the farinograph, the rates of the dough and resistance to extension and the area measured by the extensograph of composite flour dough. With increased barley flour substitution, the quality and acceptability of dough declined. However, the quality of composite flours including 10% and 15% barley flour was satisfactory.

In a biogas power plant from waste heat power generation system using Organic Rankine Cycle and multi-criteria optimization

Increasing energy consumption, rapid population growth, and technological developments have increased the need for energy demand day by day. At the point of meeting this need, renewable energy is an important alternative resource that can replace rapidly exhaustible fossil fuels. There are many renewable energy sources such as sun, wind, hydrogen, geothermal, and biogas. Biogas, one of the most important renewable energy sources, is mainly used as fuel in combined heat-power (CHP) engines/gas engines and transformed into electrical energy. However, the efficiency of these engines is low owing to the fact that a considerable amount of the energy that enters with the combustion of biogas is thrown into the atmosphere as exhaust gas. In this context, the recovery of the waste heat of 26 gas engines with a temperature of 475–500 °C in the Silivri region of Istanbul and producing biogas from household wastes was studied. Calculate the waste heat values according to the exhaust gas flow, temperature, and pressure values to be taken from the chimney outlet of the gas engines in the facility. Subsequently, the determination of the parameters of the ORC (Organic Rankine Cycle) and the optimum consumption values of the equipment in the whole system in the loop as well as the optimum ORC mechanical power will help manage and optimize the electricity production.

Research on safety early warning of abnormal A-annular pressure of “three-high” gas wells based on data mining

A major safety accident will be triggered when the A-annular pressure value of high pressure, high productivity and high sulfur gas well exceeded the maximum allowable value. The A-annular pressure value of high pressure high productivity and high sulfur gas well once exceeded the allowable value will trigger a major safety accident. Therefore, this paper proposed a data mining based the gas well early warning strategy by analyzing the annular pressure mechanism and the change in the pattern of instantaneous gas volume, well temperature, and annular pressure in various conditions. To summarize, the law of gas well abnormal A-annular pressure is aimed at constructing a gas well safety warning rule for gas well stable production stage and shutdown period where the initial parameters setting in the early warning rule and adjustment optimization mechanism is also determined. Lastly, with the use of historical abnormal samples, the gas well early warning strategy bought up in this paper was verified. The example shown that compared with the traditional DCS system warning strategy, the gas well safety early warning strategy can identify the abnormal A-annular pressure phenomenon 82 h in advance thus achieving production safety management.

Investigation of performance, combustion and emission characteristics in a diesel engine fueled with methanol/ethanol/nHeptane/diesel blends

One of the important reasons of exhaust emissions harmful to the environment and human health is the use of fossil fuels in internal combustion engines as energy resources. In this study, in order to research for cleaner fuel resources and to reduce dependence on fossil fuels, 20% methanol, ethanol and n-heptane fuels added by volume to fossil-based diesel fuel. The effects on engine performance, combustion and exhaust emission characteristics were investigated in a diesel engine with a 4-cylinder common rail injection system, at different engine loads (40 Nm and 80 Nm) and different engine speeds (1500 rpm, 1600 rpm, 1700 rpm and 1800 rpm). The maximum brake thermal efficiency (BTE) value was obtained as 43% with diesel-methanol (M20) mixed fuel at 1800 rpm at 80 Nm engine load. Brake specific fuel consumption (BSFC) values improved in all fuel types with the increase in engine load. In all test conditions, the highest maximum cylinder gas pressure (CPmax) value was obtained with M20 fuel as 114.3 bar, while the highest cumulative heat release (CHRmax) value was determined as 811.7 J with diesel-nheptane (H20) fuel. Compared to diesel fuel (D100), the use of alcohol-diesel fuel mixtures resulted in longer ignition delay (ID) and shortened combustion duration (CD). In general, a significant reduction in carbon dioxide (CO2) emissions has been observed with the use of blended fuels. As a result of the increase in engine the load, a decrease in HC emissions was observed for all test fuels. When compared to D100 fuel, oxygen (O2) and nitrogen oxide (NO) emissions were increased with the use of diesel-methanol (M20) and diesel-ethanol (E20) fuels, while O2 and NO emissions were decreased with the use of diesel-nheptane fuel.

X-ray emission from tin (Sn) using the AECS PF-2 plasma focus device

The low energy (2.8 kJ, 25 μF, 15 kV, 120 kA) AECS PF-2 Mather-type plasma focus device operated with nitrogen filling gas is used to study of the high energetic electrons beams effect on the pure tin material inserted on the copper anode tip. The operational gas pressure ranges from 0.2 mbar to 1.2 mbar. For each plasma focus discharge, the current and voltage waveforms are recorded using Rogowski coil and Ohm voltage divider, respectively. Two five channel BPX65 PIN photodiodes X-ray spectrometers (DXS) with appropriate filters are managed to estimate the X-ray yield emitted from the tin (Sn) insert (tin L-series X-ray 3.04–4.474 keV window) at the axial and radial directions. The signals of current, voltage and the temporal evolution of X-rays generated in the AECS PF-2 plasma focus device are simultaneously recorded and then analyzed for different experimental conditions. As the X-ray emission from plasma focus has a shot-to-shot variation, so for each value of gas pressure 3–10 successful shots are performed. The obtained results show that the X-ray yield decreases with increasing pressure from 0.2 to 1.2 mbar. The peak X-ray yield is found to be 0.4 J at the pressure of 0.2 mbar with efficiency ∼0.014% and the lowest values are at the highest pressure of 1.2 mbar. It can be concluded that the X-ray emission from AECS PF-2 plasma focus device depends on the pinch plasma parameters, the generated electron beam properties and the tin insert.

Development of a novel tuned liquid multiple columns gas damper under wave and earthquake incidence

A developed tuned liquid multiple columns gas damper, introduced as a TLMCGD damper, is proposed in this study and its capability is assessed on an offshore jacket platform under regular and irregular waves and also earthquake incidence. The proposed damping system includes a combination of performance of both tuned liquid multiple columns damper (TLMCD) and tuned liquid column gas damper (TLCGD). The number of multiple columns and gas pressure are defined as of the main parameters of the damper and their performance are investigated through various values under earthquake. According to the results, a passive optimum TLMCGD system can decrease the structural response of the system up to 22, 60, and 55 percent under regular wave, irregular wave, and earthquake, respectively. The whole structural response of the system reduces as the number of columns and the value of gas pressure increases up to a certain amount. To investigate the effectiveness of gas pressure in performance of the damper, various gas pressure values are considered for different 4 to 10-column TLMCGD dampers. By increasing the value of the gas, the displacement RMS reduces significantly. The highest decrement occurs as 50 to 100 bar gas pressure is specified for the gas springs of the dampers. Still more investigation is required to evaluate other key parameter of the system within an experimental study which is left for future studies.

Impact of ballistic parameters of used ammunition on stress distribution on the parts of the short recoil operated weapon

Estimation of stress distribution on the parts of a weapon is one of the most important stages of designing and optimization of firearms. The paper describes the finite element numerical model of the short recoil operated weapon and results of parametric analysis of the stress distribution on weapon parts. Considered changes in loading courses can be the result of differences in applied ammunition (produced in accordance with various standards or self-elaborated rounds). Conducted works allowed for estimation of approximate critical value of propellant gas pressure, which can be dangerous for pistol structure. Moreover, the paper presents the results of the kinematic characteristics investigation of the weapon using the finite element method and by way of the experimental tests, which proves the correctness of the assumptions made for the numerical model.

Experimental study on the guiding effect of tectonic coal for coal and gas outburst

The guiding effect of tectonic coal on outburst was analyzed by combining typical outburst cases, and the physical simulation experiment was carried out to reproduce the influences of tectonic coal area on the outburst. Then, the guiding action mechanism of tectonic coal on the outburst was investigated. This study concludes that the threshold value of critical gas pressure for outburst in the group with local existence of tectonic coal area was lower than that in the group without local existence of tectonic coal area. Under the gas pressure of 0.30 MPa in the group with local existence of tectonic coal area, the outburst hole was located inside the tectonic coal area, a part of pulverized coal was not thrown out yet, and the coal pillar experienced failure only nearby the outburst mouth. As the gas pressure increases, the failure degree of the coal pillar become higher and higher until complete failure. Based the experimental results, the outburst development sequence was changed due to the existence of the tectonic coal area. Once the sealing conditions were destructed, the outburst firstly develops in the tectonic coal area. Nevertheless, a large quantity of outburst energy would be suddenly released in the outburst process of the tectonic coal area, so sufficient energy was supplied to transport the coal in the tectonic coal area to a farther distance, while the residual outburst energy can just result in the outburst of a small quantity of coal masses in the normal area. This research will be of great scientific significance for explaining the tectonic coal-induced change of outburst starting and development sequence.