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In all air plasma sprayed (APS) environmental barrier coating (EBC) applications, the predominant goal is to achieve maximum coating density, gas tightness, and/or hermeticity prior to subjecting it to harsh environments (i.e., high-temperature impingement of high-velocity water vapor). The microstructures of APS coatings are historically understood to be influenced by the input processing parameters. Beyond the local deposition rate (surface speed, feeding rate) explored in Part I, there are further extrinsic processing parameters such as plasma gas composition, feedstock choice, and anode orifice dimensions which can be tuned, but have not been fully explored in the context of EBCs. Screening these ancillary extrinsic inputs in a rigorous and systematic way presents challenges in determining which control variable(s) to select to gain meaningful insights. A constant particle temperature distribution (not average particle temperature) in the spray stream was held as a constraint, and the aforementioned extrinsic parameters were varied. As in Part I, a qualitative microstructural approach toward examining the presence (or absence) of advantageous vertical thin microcracks in the as-deposited coating was taken. For certain conditions, a Dense Vertically Macrocracked structure was achieved. Concurrent synthesis of these results offers further insights into process selection and parameter design can be gained.

The different reservoirs in deep Songliao Basin have non-homogeneous lithologies and include multiple layers with a high content of hydrogen gas. The gas composition and stable isotope characteristics vary significantly, but the origin analysis of different gas types has previously been weak. Based on the geochemical parameters of gas samples from different depths and the analysis of geological settings, this research covers the diverse origins of natural gas in different strata. The gas components are mainly methane with a small amount of C2+, and non-hydrocarbon gases, including nitrogen (N2), hydrogen (H2), carbon dioxide (CO2), and helium (He). At greater depth, the carbon isotope of methane becomes heavier, and the hydrogen isotope points to a lacustrine sedimentary environment. With increasing depth, the origins of N2 and CO2 change gradually from a mixture of organic and inorganic to inorganic. The origins of hydrogen gas are complex and include organic sources, water radiolysis, water-rock (Fe2+-containing minerals) reactions, and mantle-derived. The shales of Denglouku and Shahezi Formations, as source rocks, provide the premise for generation and occurrence of organic gas. Furthermore, the deep faults and fluid activities in Basement Formation control the generation and migration of mantle-derived gas. The discovery of a high content of H2 in study area not only reveals the organic and inorganic association of natural-gas generation, but also provides a scientific basis for the exploration of deep hydrogen-rich gas.

During the converter steelmaking process, the presence of supersonic oxygen jets can provide oxygen to high-temperature metal baths that promotes chemical reactions in the bath, accelerates the smelting rhythm, and facilitates a uniform distribution of the ingredients in the bath. In this paper, a computational fluid dynamics (CFD) model with combustion reactions is established and compared to the results of combustion experiment. This paper studies the behavior and fluid flow characteristics of supersonic oxygen jets under different environmental compositions under a steelmaking temperature of 1873 K. This validated CFD model can be used to investigate the effect of furnace gas on supersonic oxygen jet characteristics during the converter steelmaking process. The results indicate that the composition of furnace gas has an impact on the characteristics of the oxygen jet. Specifically, as the carbon monoxide (CO) volume fraction increases, the high velocity region of supersonic oxygen jet increases, and the high temperature and the high turbulent kinetic energy regions expand.

Reliable, affordable, and clean energy supply is of considerable importance for the society, economy, and the environment. Renewable energy sources can provide several times the world’s energy demand. Biomass energy is considered a promising clean energy option for the reduction in greenhouse gas emissions and energy dependency. Among feasible technologies, biomass gasification has been considered as an enabling technology for municipal solid waste (MSW) conversion systems. The synthesis gas produced in waste-to-energy gasification of MSW can lead to their increased role in electricity generation in the future and reduces waste disposal costs. In this study, a thermodynamic equilibrium model was developed based on the downdraft fixed-bed gasifier to evaluate the effect of waste moisture content on synthesis gas composition. Besides, the equilibrium temperature of the gasifier and heating value of synthesized gas from the downdraft fixed-bed gasifier have been analyzed. Municipal solid waste of Tehran is considered as the main feed of the proposed system. The modeling results showed reasonable agreement with the experiment. The effect of operating condition on fuel moisture content and gasifier temperature was investigated. The effect of fuel moisture content on syngas compositions was also studied. The hydrogen content in the synthesis gas composition increases slightly initially to 17.9% (in moisture content 18%) but then starts reducing again. Besides, the effect of reactor temperature on synthesis gas composition was investigated.

Results are given for a study of the thermodynamic conditions of the natural gas hydrates formation in a dispersed medium saturated with water, polymer solutions and their mixtures with aqueous CaCl 2 as well as the gas composition in the resultant hydrates. Natural gas in all studied systems is found to form a mixture of hydrates of methane (first-stage hydrates with cubic structure I) and of natural gas (second-stage hydrates with cubic structure II). The equilibrium conditions of the second-stage hydrates formation are shifted toward higher temperatures by 0.5-1°C relative to the calculated equilibrium curve, this is probably caused by the concentration of C 2 -C 4 hydrocarbons in the hydrate. The presence of CaCl 2 leads to a shift of the equilibrium conditions of the second-stage hydrates formation in comparison to the calculated curves toward higher temperatures and lower pressures with an increase of C 2 -C 4 components in the hydrates. No specific effect was found for CaCl 2 on the thermodynamic conditions of natural gas hydrate formation in a dispersed medium in a mixture with polymer solutions since these data obtained for the equilibrium conditions of the natural gas hydrates formation are identical with the data obtained upon hydrate formation in solutions of CaCl 2 and water.

Although natural gas (NG) is predominantly composed of methane (CH4), the ratio of other hydrocarbon gases (e.g., ethane, propane, butane) varies substantially between production basins and sections of the supply chain. In the event of a belowground pipeline leak, NG composition impacts its transport in the belowground, surface expression, and emission into the atmosphere, complicating leak detection. Mobile survey methods do not currently account for NG composition variability, as its effect on the probability of detection (POD) remains unclear. This study investigates the impact of NG composition on POD for mobile survey methods, including walking, driving, and simulated unmanned aerial vehicle (SUAV) surveys. Four controlled belowground NG release experiments were conducted at the Methane Emission Technology Evaluation Center at Colorado State University, Fort Collins, CO. Experiments, with a constant leak rate of 5 standard liters per minute, varied in NG composition: standard distribution-grade NG (85% CH4 v/v), a control composition (70% CH4 v/v), and compositions similar to those found in the Permian Basin in Texas and the Denver-Julesburg (DJ) Basin in Colorado. Results indicate that the POD for walking, driving, and SUAV surveys is variably influenced by NG hydrocarbon composition. In simulations for the DJ and Permian Basins, walking surveys showed POD values that were 2.5 and 0.8 times higher, respectively, compared to those for distribution-grade gas. These increases are attributed to larger surface plume areas associated with higher vapor density gases, as heavier hydrocarbons promote enhanced lateral subsurface migration. In contrast, driving and SUAV surveys exhibited negligible differences relative to the distribution-grade composition, with no statistically significant attribution to compositional effects. The observed differences are more likely attributable to environmental variability than to gas-specific behavior. This statistical ambiguity highlights the need for caution when interpreting POD trends based solely on visual inspection of POD curves. To confidently attribute observed effects to gas composition, it is essential to conduct experiments across multiple test facilities, apply rigorous statistical analyses, and collect data under a broad range of environmental and subsurface conditions.

Fengyun-3E (FY-3E)/Hyperspectral Infrared Atmospheric Sounder-II (HIRAS-II) is an extension Fengyun-3D (FY-3D)/HIRAS-I. It is crucial to fully explore and analyze the detection capabilities of these two instruments for atmospheric gas composition. Based on the observed spectral data from the infrared hyperspectral detection instruments FY-3D/HIRAS-I and FY-3E/HIRAS-II, simulated radiance data and Jacobian matrices are obtained using the Rapid Radiative Transfer Model RTTOV (Radiative Transfer for TOVS (TIROS Operational Vertical Sounder)). By perturbing temperature (T), surface temperature (Tsurf), water vapor (H2O), ozone (O3), carbon dioxide (CO2), methane (CH4), carbon monoxide (CO), and nitrous oxide (N2O), the brightness temperature differences before and after the perturbations are calculated to analyze the sensitivity of temperature and various atmospheric gas components. The Improved Optimal Sensitivity Profile (OSP) algorithm is used to select the channels for atmospheric gas retrieval. The observation error covariance and background error covariance matrices are calculated, and then the information capacity is calculated, specifically the degrees of freedom for signal(DFS) and the entropy reduction (ER). Based on this, a comparative analysis is conducted on the information capacity of atmospheric water vapor and ozone components contained in the hyperspectral detection data from HIRAS-I and HIRAS-II instruments, respectively, to explore the retrieval capabilities of the two instruments for atmospheric gas components. We selected clear-sky data from the African oceanic region and the Chinese Yangtze River Delta terrestrial region for quantitative analysis of the information capacity of HIRAS-I and HIRAS-II. The results show that FY-3D/HIRAS-I and FY-3E/HIRAS-II exhibit different sensitivities to atmospheric gas components. In different experimental regions, temperature and water vapor show the most dramatic sensitivity changes, followed by ozone, methane, and nitrous oxide, while carbon monoxide and carbon dioxide exhibit the lowest variability. Regarding channel selection, HIRAS-II identifies more gas channels compared to HIRAS-I. The experiments concluded that HIRAS-II has a significantly higher information capacity than HIRAS-I, and the information capacity of atmospheric gas components varies across different experimental regions. Water vapor and ozone exhibit the highest information capacity, followed by nitrous oxide and methane, while carbon monoxide and carbon dioxide demonstrate the lowest capacity. The H2O ER (DFS) contained in FY-3E/HIRAS-II is 1.51 (0.35) higher than that in FY-3D/HIRAS-I, the O3 ER (DFS) in FY-3E/HIRAS-II is 1.51 (0.36) higher than that in FY-3D/HIRAS-I, while the N2O ER (DFS) in FY-3E/HIRAS-II is 0.17 (0.19) higher and the CH4 ER (DFS) is 0.07 (0.04) higher than that in FY-3D/HIRAS-I.

The gas composition of the Earth’s atmosphere largely determines numerous weather and climate processes and phenomena. The importance of studying the composition of the atmosphere stimulated in recent decades the creation of global and regional observation systems for water vapor, ozone and the substances depleting it, carbon dioxide and other greenhouse gases, and dozens of contaminant gases. A significant part in the global monitoring of the gas composition of the atmosphere is played by satellite observation systems which make it possible to obtain regular, global, and regional high-quality (in terms of accuracy and spatial resolution) data on its gas composition. The review is devoted to the analysis of present-day remote satellite passive methods for determining the gas composition of the atmosphere and the main results obtained to date. A modern classification of passive and active satellite methods, the physical and mathematical foundations of passive methods, the main characteristics of the used orbits of space carriers, and the types of geometry of satellite observations are given. The advantages and disadvantages of various satellite passive methods using measurements of atmospheric transparency characteristics (the eclipse method), Earth’s own radiation, as well as reflected and scattered solar radiation are analyzed for various satellite measurement geometries in a wide spectral region from UV to radio waves. A brief history of the creation of special modern satellite equipment is given, as well as their characteristics–information content, altitude measurement ranges, errors, and vertical resolution. Numerous results of global and regional monitoring of the atmospheric gas composition and examples of their use in various problems of atmospheric physics and climatology are presented.

The existing molecular relaxation models based on both parallel relaxation theory and series relaxation theory cannot extract the contributions of gas compositions to acoustic relaxation absorption in mixtures. In this paper, we propose an analytical model to predict acoustic relaxation absorption and clarify composition relaxation contributions based on the rate-determining energy transfer processes in molecular relaxation in excitable gases. By combining parallel and series relaxation theory, the proposed model suggests that the vibration-translation process of the lowest vibrational mode in each composition provides the primary deexcitation path of the relaxation energy, and the rate-determining vibration–vibration processes between the lowest mode and others dominate the coupling energy transfer between different modes. Thus, each gas composition contributes directly one single relaxation process to the molecular relaxation in mixture, which can be illustrated by the decomposed acoustic relaxation absorption spectrum of the single relaxation process. The proposed model is validated by simulation results in good agreement with experimental data such as N2, O2, CO2, CH4 and their mixtures.

The recycling of lithium-ion batteries (LIBs) is becoming increasingly important regarding the expansion of electromobility and aspects of raw material supply. Pre-treatment and liberation are crucial for a sufficient recovery of all relevant materials from LIBs. Organic removal and phase transformations by thermal pre-treatment are beneficial in many respects. This study deals with the influence of flow-gas composition on reaction products and water-based lithium recovery after thermal treatment. Therefore, a spent NMC black mass was thermally treated at 610 °C in a moved bed batch reactor under an N2 atmosphere and mixtures of N2 with 2.5% and 5% O2. Since the phase transformation of the lithium content to Li2CO3 is targeted for water leaching, a treatment under a CO2 atmosphere was studied as well. The resulting off-gas was analyzed by FTIR, and the black mass was characterized by XRD. Afterward, water washing of the black mass was carried out for selective lithium recovery. The gained lithium product was analyzed for the purity and phases present. The addition of O2 resulted in reduced reduction reactions of lithium metal oxides and lower Li-yields in the water leaching compared to the other two atmospheres. In the case of CO2, the formation of Li2CO3 is favored compared to LiF, but the Li-yield of 56% is comparable to N2 treatment.