Amount Of Air Research Articles

Optimization Method of Mine Ventilation Network Regulation Based on Mixed-Integer Nonlinear Programming

Mine ventilation is crucial for ensuring safe production in mines, as it is integral to the entire underground mining process. This study addresses the issues of high energy consumption, regulation difficulties, and unreasonable regulation schemes in mine ventilation systems. To this end, we construct an optimization model for mine ventilation network regulation using mixed-integer nonlinear programming (MINLP), focusing on objectives such as minimizing energy consumption, optimal regulation locations and modes, and minimizing the number of regulators. We analyze the construction methods of the mathematical optimization model for both selected and unselected fans. To handle high-order terms in the MINLP model, we propose a variable discretization strategy that introduces 0-1 binary variables to discretize fan branches’ air quantity and frequency regulation ratios. This transformation converts high-order terms in the constraints of fan frequency regulation into quadratic terms, making the model suitable for solvers based on globally accurate algorithms. Example analysis demonstrate that the proposed method can find the optimal solution in all cases, confirming its effectiveness. Finally, we apply the optimization method of ventilation network regulation based on MINLP to a coal mine ventilation network. The results indicate that the power of the main fan after frequency regulation is 71.84 kW, achieving a significant energy savings rate of 65.60% compared to before optimization power levels. Notably, ventilation network can be regulated without adding new regulators, thereby reducing management and maintenance costs. This optimization method provides a solid foundation for the implementation of intelligent ventilation systems.

Study on partial oxidation phenomena of post-injection fuel in diesel engines

In diesel engines, post fuel is injected in the expansion stroke, oxidized by the diesel oxidation catalysts and the high temperature gas re-generates the diesel particulate filters. However, it is empirically known that the post fuel at advanced injection timing is partially oxidized in the cylinder due to the high temperature-pressure conditions and it is a cause of the reduction of fuel consumption. The purpose of this research is to analyze post-injection fuel behaviors in cylinder and investigate the optimum fuel injections that maximize the unburnt hydrocarbons to the diesel oxidation catalysts. The engine employed in this research is a turbo charged 2.0 L four-cylinder DI diesel engine with two fuel injection systems to change the heterogeneity of air-fuel mixture and temperature distributions in cylinder; n-hexane is injected in the intake manifold to produce the homogeneous air-fuel mixture and diesel fuel is directly injected into the cylinder. The partial oxidation ratio of post fuel and the fuel loss mainly by fuel adhesion was calculated by injected fuel quantity, air quantity, and emission data. The 3D-CFD software was introduced to analyze the partial oxidation of post fuel and flow in the cylinder. The heterogeneity of burned gas mixture of post injection atmosphere and the post-injection timings were the parameters of engine tests and 3D-CFD simulations. The results suggest that the heterogeneity of equivalence ratio and the non-uniformity of gas temperature inside the cylinder at the start of post injection affect the partial oxidation of post-injection fuel. The more homogeneous these conditions are, the better the suppression of partial oxidation of post-injection fuel and the avoidance of fuel adhesion to the cylinder wall can be achieved.

Material Balance of an Electric Arc Furnace at the Libyan Iron and Steel Company

Material balance has been applied for existingElectric Arc Furnace(EAF) at the Libyan Iron and SteelCompany(LISCO) in Misurata city. First the required datawere collected from the plant, then the material balance hasbeen applied totally and on an elemental basis and led to asystem of independent material balances which has beensolved numerically. The obtained results includes thecomposition of used scrap, the quantity of infiltrated air,steel in slag , off-gas, and the electrode and refractoryconsumption. Also the results have been compared with theactual plant data and similar studies.

Analysis of distribution method of designed air quantity in coal mine ventilation—a case study

In a coal mine, air leakage exists in some roadways through doors and other ventilation structures inevitably. Based on this opinion, there are different views on whether these roadways must be assigned airflow in coal mine ventilation design. This paper analyses some relevant regulations and criteria on the designed air quantity of coal mines. Then, based on the ventilation design of the Guizhou Yizhong Coal Mine, through the study of the calculation of needed air quantity of every working place and its distribution method in coal mine ventilation design, this paper puts forward that explosion-proof door, safety exit, and other short distance roadways with ventilation structures need not assign airflow in coal mine ventilation design, while some long-distance roadways need. Additionally, it presents the main reason to support this opinion, gives the distribution method of inner air leakage quantity, which comes with the calculation of the designed mine total air quantity, puts forward the remedy method for the air leakage through ventilation structures in a coal mine ventilation system, then offers the mine operator with the basic opinions for the day-to-day planning and effective operation of a coal mine ventilation system.

Analysis of the Mathematical Models for Identifying the Thickness of the Fouling Layer in Natural Gas Coolers

This article presents an analysis of three different approaches to the identification of the thickness of the fouling layer inside the pipes of natural gas (NG) coolers. At present, there is no existing simple analytical procedure for the identification of the fouling layer thickness. The authors of this article describe in detail the balance method, which required the use of a large number of physical parameters, changes in their sizes depending on the output temperature of the gas, the temperature of the cooling air, the air quantity, as well as the physical properties of both media. The computational model was robust, and its disadvantage was the iterative computation. The second analysed method was a dimensional analysis. It was applied using the Buckingham’s theorem to express the individual similarity criteria. In this method, 10 simplexes and two complexes were created. The fouling layer thickness, expressed using a derived criterial equation, exhibited real results. The third analysed method was based on analysing selected physical parameters with the use of a multiple regression analysis in MinitabX 18 software. The analysis showed that the fouling layer thickness depended on fewer parameters than the number of parameters assumed in the dimensional analysis or the balance method. The standard deviation that was identified in the multiple linear regression for a double crossflow cooler was 0.0667 and the value of reliability (the coefficient of determination of the multiple linear regression) R2 was 0.9985.

CO-tolerance behaviors of proton exchange membrane fuel cell stacks with impure hydrogen fuel

Carbon monoxide poisoning poses a significant challenge for proton exchange membrane (PEM) fuel cells operating with CO-containing hydrogen. One established solution involves air bleeding, a process that enhances the oxidation of carbon monoxide at the anode side of the fuel cell by blending a small quantity of air with the impure hydrogen before its introduction into the fuel cell. However, researchers have raised concerns regarding durability issues about catalyst sintering and membrane decomposition induced by air bleeding. The effects and underlying mechanisms of air bleeding on PEM fuel cells have yet to be comprehensively elucidated. To address this, this study conducts a detailed durability test to quantitatively evaluate the effects of air bleeding on the CO-containing hydrogen-fueled PEM fuel cells via the micro-current excitation method. The investigation substantiates that the PtRu/C catalysts significantly enhance both the performance and durability of fuel cells when air bleeding is employed, exhibiting different CO-tolerance and decay behaviors compared to the Pt/C anode catalyst. Furthermore, the evolution of MEA parameters indicates that the advantageous behaviors of PtRu/C catalysts can be attributed to their CO-tolerance capabilities, alleviated anodic catalyst sintering and loss, and decreased chemical carbon support corrosion and membrane decomposition through diminished hydrogen peroxide generation. This study contributes critical insights and empirical evidence for researchers focusing on CO-tolerant catalyst materials, the durability of PEM fuel cells, and the conversion and utilization of impure hydrogen energy derived from fossil fuels.

Experimental Observation of the Turbulent Jet Ignition for Extending the Lean Combustion Tolerance with Carbon Dioxide Diluted Mixture

ABSTRACT Exhaust Gas Recirculation (EGR) technology is widely employed to reduce NOx emissions from engine combustion, and a major challenge of this technology is to achieve stable ignition and high burning rate at higher EGR dilution ratios. Turbulent jet ignition (TJI) is a reliable ignition resource for improving ignition stability and burning rate. Therefore, in the present work, the ability of pre-chamber turbulent jet ignition for extending the lean combustion tolerance at different EGR dilution ratios was investigated in a constant volume combustion chamber. The experimental results indicate that the methane-fueled pre-chamber and the hydrogen-fueled pre-chamber cannot improve the combustion conditions as expected. On the other hand, when an appropriate quantity of air or oxygen is injected, the EGR tolerance limit can be extended due to a decrease in the EGR concentration and an increase in the mixture reactivity in the pre-chamber. However, at higher EGR dilution ratios, more air or oxygen is required to be injected to increase the mixture reactivity in the pre-chamber, which decreases the equivalence ratio of the mixture in the pre-chamber and limits further extension of the EGR tolerance. For the mixture in the active pre-chamber under EGR dilution, the competition mechanism between EGR concentration and equivalence ratio is the key that affects turbulence intensity and chemical reactivity, thereby determining the ignition and combustion results. During the extension of the EGR tolerance limit, the variations in turbulence and chemistry are accompanied by a series of ignition modes, involving jet re-ignition, re-ignition failure, and misfire. Compared to the passive pre-chamber with an EGR tolerance limit of 18%, the air-assisted pre-chamber extended the limit to 23% and the oxygen-assisted pre-chamber to 30%.

The impact of increasing saline flush volume to reduce the amount of residual air in the delivery system of aortic prostheses-a randomized controlled trial.

Air embolism is a known risk during thoracic endovascular aortic repair (TEVAR) and is associated with an incomplete deairing of the delivery system despite the saline lavage recommended by the instructions for use (IFU). As the delivery systems are identical and residual air remains frequently in the abdominal aortic aneurysm sac, endovascular aortic repair (EVAR) can be used to examine the effectiveness of deairing maneuvers. We aimed to evaluate whether increasing the flush volume can result in a more complete deairing. Patients undergoing EVAR were randomly assigned according to flushing volume (Group A, 1× IFU; Group B, 4× IFU). The Terumo Aortic Anaconda and Treo and Cook Zenith Alpha Abdominal stent grafts were randomly implanted in equal distribution (10-10-10). The quantity of air trapped in the aneurysm sac was measured using a pre-discharge computed tomography angiography (CTA). Thirty patients were enrolled and equally distributed between the two groups, with no differences observed in any demographic or anatomical factors. The presence of air was less frequent in Group A compared to that in Group B [7 (47%) vs. 13 (87%), p = .02], and the air volume was less in Group A compared to that in Group B (103.5 ± 210.4 vs. 175.5 ± 175.0 mm3, p = .04). Additionally, the volume of trapped air was higher with the Anaconda graft type (p = .025). These findings suggest that increased flushing volume is associated with a higher amount of trapped air; thus, following the IFU might be associated with a reduced risk of air embolization. Furthermore, significant differences were identified between devices in terms of the amount of trapped air. [NCT04909190], [ClinicalTrials.gov].

A comparison between radial artery compression devices for patent hemostasis after transradial percutaneous interventions.

Patent hemostasis (PH) is essential for preventing radial artery occlusion (RAO) after trans-radial procedures; however, it remains unclear how it should be obtained. The aim of this multicenter randomized study was to evaluate whether the use of an adjustable device (AD), inflated with a pre-determined amount of air (AoA), was more effective than a non-adjustable device (non-AD) for achieving PH, thereby reducing the incidence of RAO. We enrolled a total of 480 patients undergoing transradial procedure at 3 Italian institutions. Before the procedure, a modified Reverse Barbeau Test (mRBT) was performed in all patients to evaluate the AoA to be eventually inflated in the AD. After the procedure, patients were randomized into 2 groups: (1) AD Group, using TR-Band (Terumo) inflated with the pre-determined AoA; and 2) non-AD Group, using RadiStop (Abbott). An RBT was performed during compression to demonstrate the achievement of PH, as well as 24 hours later to evaluate the occurrence of RAO. PH was more often obtained in the AD Group compared with the non-AD Group (90% vs 64%, respectively, P less than .001), with no difference in terms of bleedings. RAO occurred more often in the non-AD Group compared with the AD Group (10% vs 3%, respectively, P less than .001). Of note, mRBT was effective at guiding AD inflation and identifying high-risk patients in whom PH was more difficult to obtain. The use of AD, filled with a predetermined AoA, allowed PH significantly more often compared with non-AD, providing a significantly reduced incidence of RAO.

A comprehensive review of air conditioning condensate water supply models

Non-potable water building systems have the potential to significantly reduce water consumption, aiding in the preservation of water resources used in urban supply. Among the alternative sources of non-potable water use in buildings, clear waters stand out due to their considerable quality. Condensate water from air conditioning is a kind of clear water that is typically discarded into the sewage. Little is known about the applicability of building systems for using condensate water from air conditioning in buildings - especially within the Brazilian context. To assess the potential for reducing potable water consumption and consequently evaluate the feasibility of implementing air conditioning condensate recovery systems, it is crucial to determine the quantity of available air conditioning condensate. Therefore, this work aims to identify, through a systematic review, the models for predicting the supply of condensed water in air conditioning systems and analyze methods and variables adopted to investigate their applicability within the Brazilian climate context.

Gastric Rupture as Complication of Heimlich Maneuvre: Case Report

Background: Foreign body airway obstruction (FBAO, a.k.a. choking) is life-threatening situation, which requires an instant intervention. Among techniques to eliminate foreign body and relieve obstruction, most used is Heimlich maneuver. However, it can itself cause severe damage. Case Description: We report case of gastric rupture after successful foreign body elimination. Clinical signs were weak, diagnosis was based mostly on radiological evidence of wast quantity of free air in abdominal cavity. Urgent laparotomy revealed gastric rupture, repaired with hand-sewn sutures. Conclusions: Complications due the resuscitation, although rare, can be life threatening, so should be taken into account in every case. Public awareness and knowledge about aid and self-aid in case of choking could be improved.

Development of automatic control system of drum boiler on the basis of fuzzy controller with pid-controller adaptation

The aim of the study is to reduce energy losses in a drum steam boiler by introducing an automatic control system realized on the basis of fuzzy adaptation of proportional-integral-derivative (PID) controller coefficients using fuzzy term-multiplications. Control algorithms of the main technological parameters of the boiler unit (air quantity, fuel quantity, steam pressure, feed water flow rate), reducing energy costs due to the maintenance of the ratio of fuel and air pressure in accordance with the mode map of the boiler unit (optimal technological process of combustion and steam formation in a steam boiler) are developed. The structural scheme of the object control is offered, in which, besides regulation of values of technological parameters, full compensation of mutual influence of all regulation circuits is made.

Design and optimization of runner and gating systems, in high-pressure casting and sand casting, for an aluminum alloy valve cover

The weight and speed advantage of aluminum die-casting leads to its use in many parts in the automotive industry. Casting simulation programs are used, to avoid time-consuming and expensive production costs, and to design the production process. For casting production one of the most important factors is the runner design, which directly affects castability, material selection, and casting quality. With the correct design of runner systems, there will be no problem with the casting part. In this study, the final part and the runner design for the aluminum alloy valve cover were modeled in CAD, according to the empirical calculations. Furthermore, an appropriate casting method was selected for the valve cover not only according to the results of both high-pressure die-casting and sand-casting simulations but also economic calculations. The main technical parameters for selection were mold and part temperature distribution, liquid metal flow rates, cold shut possibilities, final air quantities, microporosity, and microporosity values. After the final decision, the casting part was produced with high pressure die casting by the implementation of the final runner design.

The temperature effect and system equilibrium of preparing powdered activated coke sorbent in a rapid carbonization-activation two-step process

ABSTRACT In this study, a rapid carbonization-activation two-step process for preparing powdered activated coke (PAC) sorbent is proposed. Shengli lignite is utilized as the feedstock to prepare PACs through this process, employing various combinations of carbonization and activation temperatures. The pore structure, surface functional groups, yield and SO2 adsorption properties of the PACs are comprehensively analyzed. Additionally, Aspen Plus software is employed to calculate the system equilibrium of this process. Results demonstrate that the performance of the prepared PAC is predominantly influenced by the activation temperature. Despite variations in carbonization temperature, consistent performance and yield are achieved as long as the activation temperature remains constant. Through the experimental design, the optimum combination of carbonization temperature and activation temperature of the two-step process is optimized, that is, the carbonization temperature is 750°C, and the activation temperature is 950°C. The SBET of the PAC prepared under optimal condition is 550 m2/g, and its SO2 adsorption capacity is 116.58 mg/g, which are both higher than that of the other ACs. The system equilibrium indicates that the optimal parameters for PAC preparation can be achieved by employing a water and air spray technique between the combustion zone and activation zone, with a water spray rate of 1.70 (kg/kg coal for combustion) and an air spray rate of 2.75 (kg/kg coal for combustion). In addition, the maintenance of system equilibrium necessitates the combustion of a certain amount of gas to elevate the temperature through the injection of a specific quantity of air into the carbonization step, with an air spray rate set at 11.00 (kg/kg coal for combustion).

The Effects of Raw Material Ratio and Calorific Value on Gasification Rate from Co-Gasification of Coal and Biomass (Bagasse)

To reduce greenhouse gas pollution by 29% in 2030 and actively fight climate change, Indonesia uses biomass as an alternative energy which can be combined with coal. Bagasse is a relatively abundant biomass that has not been effectively utilized. Bagasse can be used as a more effective alternative energy source if it is processed with co-gasification, which is the conversion of solid fuel into gas from two different fuel materials at the same time to produce syngas. The characteristics of biomass and coal co-gasification are closely linked to reactor type and gasification parameters such as temperature, gasifying agent, and mass ratio. The composition of the produced syngas changes depending on the calorific value of the coal used and the raw material ratio. The amount of syngas produced rises in direct proportion to the amount of biomass, and the quantity of air supplied causes complete combustion, so the syngas content decreases. The impact of the calorific value of the coal used, as well as variations in the ratio of the composition of coal and bagasse, on the supply of oxygen in downdraft type gasification equipment is investigated in this study. Bagasse characteristics identified by proximate and ultimate analysis indicate that this biomass can be used as an alternative source of renewable energy. The co-gasification process with 100% coal raw material has the highest temperature and the longest time; the co-gasification process with 100% sugarcane bagasse raw material has the lowest temperature and the shortest time; and the duration of the flame produced in syngas ranges from 5-6 minutes. The 25% bagasse and 75% coal ratio provided the fastest high temperature in this testing, making it more efficient. The calorific value of coal and biomass determines combustion efficiency, with 5300 cal/gr coal producing heat that lasts longer than 3800 cal/gr and 4500 cal/gr.

Pneumatic Insufflation to Confirm Distal Stoma When in Doubt.

Background Distal colostogram and ileostogram are commonly performed radiological procedures in the pediatric population. It is sometimes difficult to identify the distal stoma while performing these procedures. Aim The aim of this study was to describe a technique for the confident identification of distal stoma. Methods Injection of a small quantity of air through the catheterized stoma and following it can help to identify the stoma, as proximal or distal, based on anatomy of the delineated bowel. Conclusion Pneumatic insufflation is a simple, quick procedure to confidently identify the distal stoma whenever in doubt.

Dynamic performance analysis of the discharging process of a solar aided liquid air energy storage system

As a clean and high energy density large-scale energy storage technology, liquid air energy storage (LAES) has great development prospects. Among various LAES technologies, solar aided liquid air energy storage (SALAES) is becoming a hotspot for its cleanness and high efficiency, but its dynamic performance characteristics have not yet been revealed. In this paper, the dynamic model and control systems of the discharging process of an SALAES system considering the metal thermal inertia and axial heat conduction are established and two different start-up methods, rated parameter start-up and variable parameter start-up, are proposed and compared. Meanwhile, a parabolic trough collector control strategy with fixed outlet fluid temperature is designed to avoid DNI fluctuations that greatly affect the system's operation. Furthermore, off-design start-ups and predictable molten salt-air heat exchangers trip due to the lack of solar energy caused by continuous bad weather are noted and analyzed. Research results show that the variable parameter start-up is faster and more stable, in which the heat exchange time of two evaporators is about 895 s, the rotor speed stability time is about 12–15 s, and the load stability time is about 75–80 s. The required air quantity for the design condition start-up is 6.84 tons and will rise to 9.02 tons for the off-design start-up. The response times for the unit load to decrease from the rated value to different levels (taking 75 %, 50 %, and 25 % of the rated load as examples) are around 15–20 s, and for the trip of salt-air heat exchangers, the response time is about 20–25 s, resulting in a load fluctuation from 85.5 % to 103.6 %. The research results of this study can guide the dynamic operation of the SALAES system.

Installed Fan Noise Simulation of a Supersonic Business Aircraft

Overcoming the problem of excessive engine noise at low altitudes is a formidable task on the way to developing a supersonic passenger aircraft. The focus of this paper is on the fan noise shielding during take-off, investigated as part of the DLR project ELTON SST (estimation of landing and take-off noise of supersonic transport) for an in-house aircraft design. The supersonic inlet is required to provide the proper quantity and uniformity of air to the engine over a wider range of flight conditions than the subsonic inlet. For passenger aircraft, the noise problem influences engine integration and placement, and the new generation of supersonic transport would require innovative engineering solutions in order to come up with an efficient low-noise design. Potential solutions are evaluated using DLR tools capable of accurate source generation and noise propagation to the far-field. For low-speed aircraft operation, the method of choice is a strongly coupled volume-resolving discontinuous Galerkin (DG) and fast multipole boundary element method (FM-BEM) which is applied due to a large disparity between the Mach numbers on the interior and exterior of the inlet. The method is used for obtaining the acoustic signature of the full-scale model at realistic flight points, including the application of the programmed lapse rate (PLR), which involves simulations at higher pitch angles than for the reference flight path. The results show that the proposed method is highly suitable for obtaining accurate noise footprints during the low-speed phase and could be used to assist with certification procedures of future supersonic aircraft.

Numerical Solutions of Casson-Nano Fluid Flow Past an Isothermal Permeable Stretching Sheet: MHD, Thermal Radiation and Transpiration Effects

The Runge-Kutta Shooting Technique may be used to discover numerical solutions by the absence of magnetic field, thermal radiation, then transpiration consequence for viscous, incompressible, electrically conducting with combination of Casson and Nano-fluids that approach an isothermal permeable non-linearly stretched sheet. The governing equations for this fluid flow were transformed keen on non-linear ODEs using the similarity quantities. Visualizations of velocities, temperatures, and concentrations illustrate the mathematics behind the issue. According to tabular data, these flow regulating factors affect the coefficient of friction for skin-friction, heat transfer, and mass flow coefficients. Program code validation literature has been compared to the new numerical findings. It has been shown that flow characteristics are greatly affected by the amount of air that is exhaled. The study’s applications include industrial Nano-technological manufacturing processes. In this current work, the speed profiles are diminishing growing values of Casson fluid limitation as well as decreases by growing values of Magnetic field & Suction/Injection parameters. With increasing effects Brownian motion and Thermophoresis temperature profiles are increase. As the values of Thermal radiation of limitation enhances, the temperature profiles are also increases. The concentration profiles are increasing with increasing values of Thermophoresis parameter and reverse effect observed in case of Brownian motion effect. Also, concentration profiles decreases with increasing values of Lewis number.

The Influence of Alternative Characteristics of the Vicinity of the Ventilation District on Air Quantity

The Influence of Alternative Characteristics of the Vicinity of the Ventilation District on Air Quantity