Gas Environment Research Articles

Mathematical Simulation of the Influence of Acoustic on the Efficiency of PM 2.5 Coagulation

The particles of micron and submicron sizes (PM 2.5 and less) in gas environments pose a significant danger to humanity due to the emergence of specific and very dangerous diseases of the cardiovascular, respiratory, and immune systems of the human body. Such particles are the most difficult to detect; therefore, their effects on human health have only been discovered in recent decades. Classical ultrasonic coagulation by sinusoidal action turns out to be ineffective for PM 2.5 due to the peculiarities of the physical mechanisms of hydrodynamic and orthokinetic interaction realized in gaseous media. This article presents a theoretical justification for choosing ways to increase the efficiency of ultrasonic coagulation of PM 2.5 by creating special conditions under which nonlinear disturbances of the velocity and pressure of the gas phase in the ultrasonic field occur. The authors performed simulations of ultrasonic coagulation under nonlinear disturbances of the velocity (vortex) and the pressure (shock waves), which has numerical difficulties due to the instability of existing methods. As a result of the numerical analysis, the possibility of increasing the coagulation rate of particles in the submicron size range up to limit values (13 times due to nonlinear pressure disturbances, and an additional increase of at least 2 times due to aerosol compaction in the vortex field of gas velocity) was shown.

Ignition characteristics of single coal particles under ammonia co-firing conditions

To meet the goal of an international carbon-neutral framework, the promotion of clean coal utilization occupies a vital position in reducing greenhouse gas emissions. Ammonia co-firing is considered as a potential strategy for future power generation to reduce fossil energy consumptions, soot, CO2 emissions, and hydrocarbon pollutants. In the present work, the ignition characteristics of single coal particles under ammonia (NH3) co-firing conditions were investigated. Particles were injected with NH3 or N2 into a hot flue gas environment at 1550 K generated by a CH4-fired Hencken burner. Temporally resolved images of CH* chemiluminescence and char thermal radiation were captured. Combining the signal profiles, ignition modes and characteristic times of single burning particles were studied with different coal types, carrying atmospheres, and O2 contents. When the carrier gas was replaced by NH3 atmosphere, the ignition delay time of all coal particles was greatly shortened, and the time interval from ignition to peak, as well as the combustible component burnout time, were both lengthened due to the promoted devolatilization and combustion reaction rates of coal particles caused by the NH3 flame. Concerning the ignition mode in the NH3-blended cases, the homogeneous ignition behaviors of the lignite particles were further enhanced, while the bituminous particles transitioned to the homogeneous-heterogeneous united ignition mode. As the O2 content in the flue gas increased, the ignition of all coal particles was advanced monotonously, and the chemiluminescence became more intense in both N2 and NH3 atmospheres.

Study on the Effect of Polyamine Water Treatment Agent on Metal Corrosion Inhibition in Boiler Steam-Water System.

A polyamine water treatment agent was prepared with the film-forming amine (N-oleyl-1,3-propylenediamine) and the neutralizing amine (cyclohexanamine) under optimal conditions. The copper sulfate liquid drop experiment showed that a protective film was formed by the polyamine water treatment agent on carbon steel. The analyses of the polarization curve and electrochemical impedance spectroscopy of carbon steel indicated that the polyamine water treatment agent exhibited geometric effects, which could inhibit both anode and cathode reactions of carbon steel, and the corrosion inhibition effect of the polyamine water treatment agent showed an extreme-concentration phenomenon. A metal corrosion experiment in a simulated boiler steam-water system indicated that the polyamine water treatment agent mitigated the corrosion of carbon steel at different temperatures, and the corrosion inhibition rates of the polyamine water treatment agent in liquid and gas environments at 150 °C were 53.84% and 67.43%, respectively, better than that at 350 °C. SEM-EDS characterization indicated that the formation of the corrosion product, iron oxide, on the carbon steel was reduced with the addition of the polyamine water treatment agent in the simulated boiler steam-water system.

Study on the Influence of Different Gas Concentrations on Coal Spontaneous Combustion

ABSTRACT The coexistence of gas and spontaneous coal combustion poses a serious threat to mine production safety. Therefore, studying the compound disaster of gas and spontaneous coal combustion and revealing the impact of gas concentration on the characteristic parameters of coal spontaneous combustion are of great significance for understanding the mechanism of compound disasters involving coal and gas and for comprehensive management. Based on theoretical analysis, this paper selects four typical types of cannel coal、non-caking coal、meager coal、anthracite coal as research subjects, and conducts programmed heating experiments on coal samples under different gas concentration conditions, aiming to provide a theoretical basis for the prevention and control of spontaneous coal combustion in a gas environment. Experimental results show that with the increase in temperature of the coal samples, the oxygen consumption rate and heating emission intensity exhibit a trend of slow increase followed by rapid increase. With the increase in gas concentration in the environment, the production of CO and CO2, oxygen consumption rate, and heat emission intensity of coal spontaneous combustion all show a decreasing trend. This is mainly because the high gas concentration occupies the adsorption sites on coal molecules, thereby hindering the reaction between coal and oxygen. Additionally, by calculating the thermodynamic parameters of the coal samples, it was found that the apparent activation energy increases with the increase in gas concentration, further confirming that the increase in gas concentration in the environment significantly inhibits the spontaneous combustion process of coal.

Laser surface cleaning of simulated radioactive contaminants in various technological environments

Special methods for cleaning surfaces of stainless steel with a coating simulating radioactive contamination have been developed and studied. The removal of simulated surface contamination was performed using lasers in the micron spectral range with pulse durations of 8 ns and 270 fs. Optimal cleaning modes were determined for gas and liquid environments, achieving surface cleaning coefficient of over 90% in a single pass. A correlation between the degree of cleaning in liquids and the viscosity of the environment was discovered.

Development of a super-hydrophilic anaerobic tube for the optimization of platelet-rich fibrin

Horizontal platelet-rich fibrin (H-PRF) contains a variety of bioactive growth factors and cytokines that play a key role in the process of tissue healing and regeneration. The blood collection tubes used to produce Solid-PRF (plasmatrix (PM) tubes) have previously been shown to have a great impact on the morphology, strength and composition of the final H-PRF clot. Therefore, modification to PM tubes is an important step toward the future optimization of PRF. To this end, we innovatively modified the inner wall surface of the PM tubes with plasma and adjusted the gas environment inside the PM tubes to prepare super-hydrophilic anaerobic plasmatrix tubes (SHAP tubes). It was made anaerobic for the preparation of H-PRF with the aim of improving mechanical strength and bioactivity. The findings demonstrated that an anaerobic environment stimulated platelet activation within the PRF tubes. After compression, the prepared H-PRF membrane formed a fibrous cross-linked network with high fracture strength, ideal degradation characteristics, in addition to a significant increase in size. Thereafter, the H-PRF membranes prepared by the SHAP tubes significantly promoted collagen synthesis of gingival fibroblast and the mineralization of osteoblasts while maintaining excellent biocompatibility, and advantageous antibacterial properties. In conclusion, the newly modified PRF tubes had better platelet activation properties leading to better mechanical strength, a longer degradation period, and better regenerative properties in oral cell types including gingival fibroblast and alveolar osteoblasts. It also improves the success rate of H-PRF preparation in patients with coagulation dysfunction and expands the clinical application scenario.

Utilizing rubidium chloride as an effective andstable interface modification layer forhigh-efficiency solar cells.

The presence of interface defects between the perovskite layer and the underlying substrate has a significant impact on the power conversion efficiency (PCE) and stability of perovskite solar cells (PSCs). S n O 2 thin films are employed in PSCs as electron transport layers to achieve high PCE. However, the significant lattice mismatch between S n O 2 and the perovskite material leads to a large number of uncoordinated defects at the interface between perovskite and substrate, resulting in recombination losses at the interface. In this study, rubidium chloride (RbCl) was introduced as the interface modification layer between the perovskite layer and the S n O 2 electron transport layer to enhance the PCE of PSCs. The research showed that the RbCl interface modification layer effectively passivated the under-coordinated defects of Sn ions and optimized the energy level alignment between the perovskite layer and the S n O 2 film. Moreover, the fabricated PSCs exhibited an open-circuit voltage of 1.11V and a power conversion efficiency of 21.64%. Furthermore, the device maintained 80% of initial efficiency after storage for 30days in an inert gas environment and 60% of the value after storage for 30days in ambient air.

Real-Time Tracking of Carbon Dioxide Concentration Using an Optical Microsphere Resonator Sensor.

Whispering gallery mode resonator sensors are nondisruptive optical sensors that can detect and monitor perturbations in a gaseous environment. Through its resonant properties of peak wavelength, amplitude, and quality factor (Q factor), changes in concentration can be quantified within seconds and monitored over days with great stability. In addition, the small footprint, low cost, and high sensitivity are ideal properties for a disposable sensor that can be utilized in extreme environments. The large Q factor of the resonant cavity enables long interaction lengths and amplifies the effect of small changes in the background refractive index, which is detectable in picometer shifts of the resonance wavelength. However, this measurement is susceptible to changes in other environmental factors such as temperature, pressure, and humidity, which manifest on the picometer wavelength scale, reinforcing the need to decouple the variables. In this work, we compare the spectral response of different diameter resonators to carbon dioxide, nitrogen, and its mixtures, observing the spectral shifting and broadening of the cavity resonance near 1550 nm. In addition, the effect of environmental temperature on spectral shifting due to the thermo-optic effect is characterized and quantified. Lastly, the gas concentrations are changed in real time to showcase the tracking and recovery capabilities of the resonator sensor.

The Effect of CuO on the Thermal Behavior and Combustion Features of Pyrotechnic Compositions with AN/MgAl

Ammonium nitrate (AN) is of considerable interest to researchers in developing new types of energetic mixtures due to the release of environmentally benign gaseous products during burning and thermal decomposition. However, poor ignition and a low burning rate require special additives to speed up this process. The advantage of this research is the use of high-energy aluminum-based alloys as fuel to compensate for the disadvantages of AN. In addition, the effect of copper oxide (CuO) on the burning kinetics and thermodynamics of the energetic mixture based on ammonium nitrate–magnesium–aluminum alloys (AN/MgAl) is investigated. Alloys based on aluminum were created through a process of high-temperature diffusion welding, conducted in an environment of argon gas. The structure and thermal characteristics of alloys are determined by X-ray diffraction, scanning electron microscopy, and DTA-TG analyses. It has been found that CuO has significant effects on the thermal decomposition of an AN/MgAl-based energetic mixture by shifting the decomposition temperature from 269.33 °C to 261.34 °C and decreasing the activation energy from 91.41 kJ mol−1 to 89.26 kJ mol−1. Adding CuO reduced the pressure deflagration limit from 2 MPa to 1 MPa, and the linear burning rate of the AN/MgAl energetic mixture increased approximately twice (rb = 6.17 mm/s vs. rb = 15.44 mm/s, at a chamber pressure of P0 = 5 MPa).

Experimental study on the freezing process of water droplets for ice air jet technology

Ice air jet technology is one non-destructive, residue-free and environmentally friendly machining process. It is an efficient method to form ice particles by atomizing water droplets in ultra-low temperature environment. The freezing characteristics of water droplets in cryogenic gas and liquid nitrogen environment are visually analyzed, and the effects of droplet volume, ambient temperature are also studied. The results show that when water droplets freeze in a cryogenic gas environment, four distinct stages are observed, namely pre-cooling stage, recalescence stage, solidification stage, and deep cooling stage. However, when water droplets freeze in liquid nitrogen, the recalescence stage cannot be observed. For a 5 µl water droplet, it takes 68 s for water droplets to freeze into ice particles at − 20.36 °C, while it takes only 1.7 s in liquid nitrogen. During the freezing process, the water droplets form an ice shell outside and freeze inwardly. Ice particles may break up due to differences in solubility and density. With the increase of volume the time spent on pre-cooling stage and freezing stage both increases. For the large latent heat of water phase transformation, the solidification stage time is greatly affected by the volume of water droplets. When the ambient temperature drops from − 10.67 °C to − 24.68 °C, the freezing time of 5 µl water droplets decreases by 45.5%, indicating that the ambient temperature has a great influence on the freezing time. The results of the study can significantly contribute to the development of ice air jet technology.

Effect of Gas Environment on Metal‐Support Interactions of Supported Metal Catalysts

AbstractSupported‐metal catalysts, pivotal for industrial applications, have their catalytic properties affected by metal‐support interactions (MSIs), which notably influence both their electronic and geometric characteristics. Therefore, understanding internal and external factors that influence MSIs is crucial for the rational design of catalysts. Our minireview focuses on the effects of the gas environment on the MSIs, particularly the morphological changes in metal nanoparticles, the migrating behavior of reducible supports (strong metal‐support interaction), and the compositional rearrangement of the catalysts (reactive metal‐support interaction). Future directions are suggested to elucidate the fundamental aspects of gas environment induced structural reconstruction of catalysts, including the quantitative analysis of dynamic behavior of both the surface and interface, atomic‐level insights into the structures of the metal, support, and interface under pertinent conditions through advanced in situ/operando characterization, and the in situ manipulation of structural reconstruction.

SiCf/SiC composites tolerance to high temperature combustion atmosphere and post ageing mechanical and microstructural characterisation

This article reports the activities carried out under WP4, coordinated by ENEA, within the CEM-WAVE European project, about experimental study on SiCf/SiC composites tolerance to high temperature combustion atmosphere. Water corrosion phenomena are known to affect mechanical properties of SiC-based CMC, due to the formation of a silica, volatile in certain condition. The study will simulate combustion conditions, aiming at using more environmentally friendly alternatives to methane, such as hydrogen, coke oven gas or biomethane, in steel production. It is essential to determine, in each case, if corrosion happens in active (that means continuous degradation) or passive (silica forms a protective “scale” on the component) regime. Since fibre-to-matrix interface can also be degraded, it is important to determine post-ageing mechanical flexural strength (by 4point bending tests). Water corrosion ageing was performed by means of direct flame exposure. When the oxidizing species becomes CO2, instead of O2, the formation rate of silica passivating layer is expected to be lower than the volatilization rate, and consequently active oxidation results in continuous weight loss. Ageing tests of SiCf/SiC composites were carried out at high temperature in a CO2/H2O/N2 gaseous environment at atmospheric pressure (reference conditions: 1200°C, 10/20/70 v/v). Bending tests up to failure are carried out at room temperature on these aged samples after different exposure times. Relationships are established between the evolution of mechanical properties, the ageing conditions, and the rates of oxidation reactions.

Optoelectronic Synapses Based on MXene/Violet Phosphorus van der Waals Heterojunctions for Visual-Olfactory Crossmodal Perception

HighlightsThe photoelectric response of violet phosphorus (VP) is significantly enhanced by the MXene/VP van der Waals heterojunctions and the highest photoresponsivity of VP is demonstrated.The first VP-based optoelectronic synapse with essential synaptic behaviours is demonstrated.Proof-of-concept visual-olfactory crossmodal perception based on MXene/VP optoelectronic synapses is explored to mimic neuromorphic vision with multi-sensory interactions.

A comprehensive study on applications of nanomaterials in petroleum upstream and downstream industry.

Nanotechnology has emerged as a revolutionary technology that has been applied in the oil and gas industry for over a decade, spanning the upstream, midstream, and downstream sectors. Nanotechnology has made significant contributions to the exploration of crude oil and natural gas, both in underground and deep-water environments. It has also played a crucial role in improving the drilling process, enabling the extraction of oil and gas resources from beneath the Earth's surface. Nanoparticles, with their unique physical and chemical properties, such as high specific surface area, high pore volume, and small size, have demonstrated considerable potential in the oil industry. Extensive research has been conducted to explore various types of nanoparticles for advanced applications, including oil exploration, drilling, production, and enhanced oil recovery (EOR). Moreover, nanomaterials have found applications in downstream and intermediate sectors, such as crude oil refining, natural gas processing, and transportation and storage of petroleum products. Ongoing advancements in nanomaterial synthesis methods, the exploration of new nanomaterial uses, and understanding the remarkable properties of nanomaterials will continue to make them increasingly valuable in the oil and gas sector. The oil and gas industry recognises the potential of nanotechnology and nanoparticles and is investing significantly in research and development in this area. This comprehensive review aims to summarise successful applications of nanotechnology while addressing associated challenges. It serves as a valuable resource for future research and application endeavours in the field, highlighting the potential of nanotechnology in the oil and gas industry.

Synthesis and characterization of low-friction W-V-N alloy coatings using reactive magnetron sputtering technique for tribological applications

In recent years, self-lubricating hard coatings have garnered significant interest across various industries such as cutting tools, molds, and manufacturing because of their ability to reduce friction and wear at high temperatures in dry-cutting applications. The present study focuses on synthesis of tungsten-vanadium-nitride (W-V-N) coatings using the reactive magnetron cosputtering technique in an Ar + N2 plasma gas environment. The coating microstructure, surface morphology, wetting behavior, and mechanical properties were characterized by grazing incidence x-ray diffraction, field-emission scanning electron microscopy, atomic force microscopy, energy-dispersive spectroscopy, and nanoindentation. Wear resistance properties of the prepared W-V-N alloy coatings were investigated using a ball-on-disk tribometer at two different temperatures. The findings indicate that all W-V-N coatings, regardless of the vanadium content, exhibit a face-centered cubic structure and form a solid solution of W-V-N. Among the coatings studied, W0.68V0.32N exhibited the highest hardness (14.25 GPa) and Young's modulus (257.53 GPa), as well as an excellent wear resistance. Increasing the vanadium content in the W-V-N coating led to a notable reduction in both the specific wear rate and friction coefficient. Moreover, this reduction was more pronounced with an increase in temperature during the wear test. Improvement in the wear properties can be attributed to the formation of Magnéli phases of vanadium oxides on the surface of the coatings. The ability of the W-V-N coating to reduce friction and wear, combined with its improved mechanical properties, makes it a promising candidate for solid lubricating coatings in tribological applications.

Preparation of hydroxypropyl methylcellulose/pueraria-based modified atmosphere film and its influence on delaying the senescent process of postharvest Agaricus bisporus

Based on the key factor of spontaneous modified atmosphere packaging (MAP)—gas permeability, a spontaneous MAP film was created for the preservation of Agaricus bisporus by delaying the senescence of white mushrooms. Compared with other mixed films, hydroxypropyl methylcellulose (HPMC)/pueraria (P)-2 showed better mechanical properties, barrier properties and thermal stability energy. Applying the HPMC/P-2 film for preserving white mushrooms can spontaneously adjust the internal gas environment. Moreover, the O2 concentration in the package remained stable at 1–2 %, and the CO2 concentration was between 8 % and 14 %. The film can effectively reduce the respiration rate of white mushrooms, inhibit enzymatic browning, maintain their good color and texture, and delay their aging. In conclusion, the HPMC/P-2 film can be used not only for fruit and vegetables preservation but also provide theoretical basis for sustainable food packaging.

Investigating the adsorption potential and sensitivity of pristine along with carbon, boron, and nitrogen substituted hetero-nanocages towards azacitidine drug

The use of nanomaterials as carriers for the delivery of a diverse array of anticancer drugs and their application as effective sensors in clinical environments has been steadily growing as a result of advancements in nanoscience. Using density functional theory at the B3LYP-D3/6-31G(d,p) level, this study made a comparative adsorption efficiency assessment of pure C24 and B12N12 nanocages along with some of their hetero-counterpart nanocages toward the anticancer drug azacitidine. Out of the nanostructures that were examined in this study, B6C6N12 nanocage appeared as the most prominent adsorbent by developing drug delivery conjugated structure that demonstrates the highest degree of stability in adsorbing the azacitidine, making it most suitable for transportation or detection purposes in both gaseous and aqueous environments. The confirmation of the interaction between the azacitidine and the adsorbents is further supported by examining frontier molecular orbitals, natural bond orbital, quantum theory of atoms in molecules, and non-covalent interaction analysis. The simulation of ultraviolet–visible spectra was performed for all systems to assess the feasibility of using ultraviolet–visible spectroscopy to track and monitor the binding of azacitidine to the suggested adsorbents. The findings presented here open up endless possibilities for these nanocages as drug delivery and detection systems of nanomedicine.

Laser-Induced Thermal Decomposition of Uranium Coordination Compounds with Non-oxidic Ligands to Produce Nitride and Carbide Materials.

The production of ceramics from uranium coordination compounds can be achieved through thermal processing if an excess amount of the desired atoms (i.e., C or N), or reactive gaseous products (e.g., methane or nitrogen oxide) is made available to the reactive uranium metal core via decomposition/fragmentation of the surrounding ligand groups. Here, computational thermodynamic approaches were utilized to identify the temperatures necessary to produce uranium metal from some starting compounds─UI4(TMEDA)2, UCl4(TMEDA)2, UCl3(pyridine)x, and UI3(pyridine)4. Experimentally, precursors were irradiated by a laser under various gaseous environments (argon, nitrogen, and methane) creating extreme reaction conditions (i.e., fast heating, high temperature profile >2000 °C, and rapid cooling). Despite the fast dynamics associated with laser irradiation, the central uranium atom reacted with the thermal decomposition products of the ligands yielding uranium ceramics. Residual gas analysis identified vaporized products from the laser irradiation, and the final ceramic products were characterized by powder X-ray diffraction. The composition of the uranium precursor as well as the gaseous environment had a direct impact on the production of the final phases.

Effects of ignition voltage and electrode structure on electric ignition and combustion characteristics of Ammonium Dinitramide (ADN)-based liquid propellants in electric ignition mode in inert gas environment

Hydrazine is toxic and carcinogenic, which greatly increases the difficulty of application and no longer meets the needs of green aerospace. As a green propellant, the Ammonium Dinitramide (ADN)-based liquid propellant has the advantages of higher specific impulse, being non-toxic, pollution-free, and easy storage. However, an ADN-based space engine in orbit has exposed the problems of high-temperature deactivation of catalysts and cold-start failure. An active ignition technology—electric ignition technology was explored in this paper to break through the technical bottleneck of catalyst deactivation and the inability to a cold start. An experimental system of a constant-volume combustor for the ADN-based liquid propellant based on the electric ignition method was established. The electric ignition and combustion characteristics of the ADN-based liquid propellant in a volume combustor with an electric ignition method were studied. The influencing mechanisms of the ignition voltage and the electrode structure on the electric ignition characteristics of the ADN-based liquid propellant were investigated. An elevation of the ignition voltage could facilitate the ignition process of the ADN-based liquid propellant, curtail electric energy input and heating effect, while exerting an adverse impact on the combustion process of the propellant. An increase in the ignition voltage enhanced the ignition process of the propellant while simultaneously suppressing its combustion process when utilizing mesh electrodes. Compared to the strip electrodes, the mesh electrodes increased the contact area between the electrodes and the propellant, increased the electric energy input power in the electric ignition process, and reduced the ignition delay time. The mesh electrodes could promote the combustion process of the propellant to a certain extent.

Ion molecule reaction dynamics for disentangling competing reactive pathways

ABSTRACT Chemical reactions are by definition dynamical. Reactants move towards each other, collide and products separate again. Therefore, it is important to look beyond the stationary description, and look at how molecules rearrange and how energy is partitioned during a reactive collision. Chemical reactions are complex and often involve competing chemical and/or atomistic pathways whose dominance depends on several factors as for example the involved quantum states or collision energy. Here, we focus on ion molecule reactions which play an important role in gaseous environments even though their steady-state abundance is often much lower than that of their neutral counterparts. We present the use of angle and energy differential cross sections from crossed beam imaging experiments to disentangle competing reaction pathways. The general term pathways includes different effects of specific reactant quantum states on the atomistic mechanism to the competition of different product channels.