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Underground hydrogen storage (UHS) critically relies on cushion gas to maintain pressure balance during injection and withdrawal cycles, prevent excessive water inflow, and expand storage capacity. Interfacial tension (IFT) between brine and hydrogen/cushion gas mixtures is a key factor affecting fluid dynamics in porous media. This study develops four machine learning models— Decision Trees (DT), Random Forests (RF), Support Vector Machines (SVM), and Multi-Layer Perceptrons (MLP)—to predict IFT under geo-storage conditions. These models incorporate variables such as pressure, temperature, molality, overall gas density, and gas composition to evaluate the impact of different cushion gases. A group-based data splitting method enhances the realism of our tests by preventing information leakage between training and testing datasets. Shapley Additive Explanations (SHAP) reveal that while the MLP model prioritizes gas composition, the RF model focuses more on operational parameters like pressure and temperature, showing distinct predictive dynamics. The MLP model excels, achieving coefficients of determination (R2) of 0.96, root mean square error (RMSE) of 2.10 mN/m, and average absolute relative deviation (AARD) of 3.25%. This robustness positions the MLP model as a reliable tool for predicting IFT values between brine and hydrogen/cushion gas (es) mixtures beyond the confines of the studied dataset. The findings of this study present a promising approach to optimizing hydrogen geo-storage through accurate predictions of IFTs, offering significant implications for the advancement of energy storage technologies. • ML techniques were used to estimate IFT in H 2 /cushion gas (es)-brine systems. • A novel data splitting method focused on gas composition over sample quantity. • Inputs were pressure, temperature, molality, overall gas density, and gas composition. • The MLP model outperformed other models. • Shapley Additive Explanations (SHAP) approach was used to interpret the results. [ABSTRACT FROM AUTHOR]

This study aims to clarify the effect of oxygen in shielding gas on weldability in the plasma-GMA (Gas Metal Arc) hybrid welding process of high-tensile strength steel plates. The difference in keyhole profile and bead formation, when the GMA shielding gas was pure Ar, Ar + 2% O2, or Ar + 20% CO2, was investigated for plate thicknesses of 6 and 9 mm for the first time. It was found that the weld beads were in good condition for 6 mm thickness plates for all shielding gases, which implied that the window of welding conditions for this thickness is wide. In contrast, for 9 mm thickness plates, a fully penetrated weld bead was achieved only in Ar + 20% CO2, and weld bead penetration in Ar + 20% CO2 is higher than in pure Ar and Ar + 2% O2 in the same welding condition. Due to decreased surface tension caused by sufficiently increased oxygen absorbed into the weld pool, the keyhole diameter increased to penetrate the bottom side of the plate, and the depressing weld pool surface under GMA allowed the heat input from the GMA to be directly applied to a deeper position. Consequently, the plasma-GMA hybrid welding process with Ar + 20% CO2 achieved a complete penetration for a plate of 9 mm thickness, owing to the effects of both phenomena. It proved a potential to increase penetrability in welding thicker plates by controlling oxygen content in shielding gas of GMA adequately. [ABSTRACT FROM AUTHOR]

Background: Fire models have used pyrolysis data from oxidising and non-oxidising environments for flaming combustion. In wildland fires pyrolysis, flaming and smouldering combustion typically occur in an oxidising environment (the atmosphere). Aims: Using compositional data analysis methods, determine if the composition of pyrolysis gases measured in non-oxidising and ambient (oxidising) atmospheric conditions were similar. Methods: Permanent gases and tars were measured in a fuel-rich (non-oxidising) environment in a flat flame burner (FFB). Permanent and light hydrocarbon gases were measured for the same fuels heated by a fire flame in ambient atmospheric conditions (oxidising environment). Log-ratio balances of the measured gases common to both environments (CO, CO2, CH4, H2, C6H6O (phenol), and other gases) were examined by principal components analysis (PCA), canonical discriminant analysis (CDA) and permutational multivariate analysis of variance (PERMANOVA). Key results: Mean composition changed between the non-oxidising and ambient atmosphere samples. PCA showed that flat flame burner (FFB) samples were tightly clustered and distinct from the ambient atmosphere samples. CDA found that the difference between environments was defined by the CO-CO2 log-ratio balance. PERMANOVA and pairwise comparisons found FFB samples differed from the ambient atmosphere samples which did not differ from each other. Conclusion: Relative composition of these pyrolysis gases differed between the oxidising and non-oxidising environments. This comparison was one of the first comparisons made between bench-scale and field scale pyrolysis measurements using compositional data analysis. Implications: These results indicate the need for more fundamental research on the early time-dependent pyrolysis of vegetation in the presence of oxygen. Composition of pyrolysis gases measured in non-oxidising and ambient atmospheric conditions has been compared using compositional data analysis. Mean compositions changed between the non-oxidising and ambient atmosphere samples. These results indicate the need for more fundamental research on the early time-dependent pyrolysis of vegetation in the presence of oxygen. [ABSTRACT FROM AUTHOR]

The scientific article describes a mathematical method for calculating the amounts of hydrocarbon gases at different stages of hydrocarbon processing, starting from mixing hydrocarbon feed streams and ending with monitoring the accuracy of product yields. This integrated approach ensures systemic improvement of all processing processes. The scientific article contains examples of calculations, which makes the methodology accessible for use by industry specialists. This makes it easy to adapt and apply the proposed methods in various production conditions. These aspects emphasize the high significance and innovativeness of the scientific work performed, contributing to solving pressing problems of hydrocarbon processing and increasing the efficiency of the petrochemical industry. [ABSTRACT FROM AUTHOR]

The cultivation of green leafy vegetables is crucial for improving our nation's nutritional security. Challenges like limited arable land and excessive fertilizer use have become significant concerns on cultivating in open field. To address these issues, vertical farming technology, with a focus on space optimization and hydroponic integration to manage fertilizer use, is gaining attention. This experiment aims to determine the best growing media and nutrient solutions for palak in an A-framed vertical unit. Three growing media were tested: coir pith (M0), Rockwool (M1), and a 1:1 mix of coir pith and vermiculite (M2). Various combinations of water-soluble fertilizers [Ca (NO3)2, MAP, and SOP] were used for each crop's nutrient recipe preparation. Optimal yields were achieved when palak were grown in a coir pith and vermiculite mix with nutrient concentrations of 60:50:60 ppm. Despite high yields, green leafy vegetables face rapid spoilage and storage challenges. The study examined factors affecting post-harvest quality, including storage conditions (ambient at 35 ± 5°C, refrigerated at 5 ± 5°C), packing substrates (low-density polyethylene, high-density polyethylene covers), and gas compositions with modified atmosphere packaging. Results showed that refrigerated storage with low-density polyethylene packing and a gas composition of 6% O2, 5% CO2, and 89% N2 (G2) resulted in the least deterioration in physiological attributes and overall visual quality. This study highlights the potential of vertical farming technology, precise nutrient management, and advanced post-harvest techniques for sustainable production and preservation of green leafy vegetables to meet our nation's nutritional security needs. [ABSTRACT FROM AUTHOR]

The article presents the results of study of ferruginous mineral waters. The waters under consideration are discharged on the territory of Western Transbaikalia and belong to the anoxic sulfide-free and acidic types. The peculiarities of the formation of gas, major and trace elements, and dissolved organic substance composition have been established using modern methods. It has been shown that the chemical composition of the waters is greatly influenced by acid–base conditions. Acidic ferruginous waters contain large amounts of heavy metals; organic matter is mainly represented by low molecular weight organic compounds. The only metals present in significant amounts in ferruginous waters are manganese and zinc. Dissolved organic matter is represented by diverse types of high-molecular weight compounds that are formed as a result of biotic processes. [ABSTRACT FROM AUTHOR]

This study explores the synergistic effects of gas composition and electric field modulation on beetroot seed germination using dielectric barrier discharge (DBD) plasma. The investigation initially focuses on the impact of air plasma exposure on germination parameters, varying both voltage and treatment duration. Subsequently, the study examines how different gas compositions (argon, nitrogen, oxygen, and carbon dioxide) affect germination outcomes under optimal air plasma conditions. Results indicate that plasma treatment significantly enhances germination rates and seedling growth relative to untreated controls. Notably, plasma exposure alters seed surface morphology and chemistry, increasing roughness, porosity, and hydrophilicity due to the formation of new polar functional groups. The highest germination rate (a 54.84 % increase) and germination index (a 40.11 % increase) were observed at the lowest voltage and shortest duration, whereas higher voltages and prolonged exposure reduced germination, likely due to oxidative stress. Among the tested gas environments, air plasma was most effective in enhancing water uptake and electrical conductivity, while oxygen plasma resulted in the highest germination index and marked improvements in root and shoot length. Conversely, carbon dioxide plasma treatment exhibited inhibitory effects on both germination and subsequent growth metrics. The results highlight the potential of DBD plasma technology to enhance agricultural productivity by optimizing seed germination and early growth. The study emphasizes the importance of precise parameter tuning, particularly gas composition and plasma exposure conditions, to maximize benefits while minimizing adverse effects, offering a refined approach to seed priming in agricultural practices.

Oil-immersed transformers are widely used in power systems. When an arc fault occurs inside a transformer, the surrounding oil is rapidly pyrolyzed. These high-temperature, flammable gases are compressed into a high-pressure bubble, which is likely to cause tank deformations, explosions, and fires. Currently, related simulations on tank internal pressure and transformer fires are based on a constant gas composition, a constant gas production rate of 0.1 L/kJ, and a constant bubble temperature of 2000 K. This paper deals with a case of a power-frequency arc (5 kA, 30 mm, 80 ms) in transformer oil. The time-varying characteristics of pyrolyzed gas production, composition, and temperature are experimentally investigated. The percentage of hydrogen changes considerably, decreasing from 85.2 % to 70 %. The overall gas production rate increases slowly from 0.0574 L/kJ in the first 2.5 ms to 0.0982 L/kJ in 80 ms. The local temperature inside the main bubble (30 mm from the arc) decreases gradually from 2200 K to 1400 K, while the average bubble temperature decreases from 2550 K to 550 K. This case and these results provide an experimental basis for the parameter selections in the simulations about transformer internal pressure and fire progression.

The results of experimental studies of the process of electroslag remelting of titanium in a chamber furnace at different values of pressure in the melting space, from vacuum to excess pressure, are given. Experiments were carried out during the melting of ingots with a diameter of 85 and 105 mm from titanium alloys VT1-0 and VT22 using fluoride-chloride flux AN-T4. The pressure of the inert gas in the furnace chamber was varied from 20 to 300 kPa. It is shown that in the entire studied range of pressures, the electroslag process proceeded stably with the formation of ingots with a high-quality side surface and a dense structure, without pores, slag inclusions and other internal defects. Experimental data on the effect of pressure in the melting space on the gas composition and structure of titanium ingots are given. the possibility of reducing the hydrogen content in titanium alloys by carrying out the electroslag process in vacuum conditions is shown. It was also established that the VT1-0 titanium ingot, melted under vacuum conditions, is characterized by a larger grain size compared to the ingot obtained under excess pressure. [ABSTRACT FROM AUTHOR]

The cultivation of green leafy vegetables is crucial for improving our nation’s nutritional security. Challenges like limited arable land and excessive fertilizer use have become significant concerns on cultivating in open field. To address these issues, vertical farming technology, with a focus on space optimization and hydroponic integration to manage fertilizer use, is gaining attention. This experiment aims to determine the best growing media and nutrient solutions for palak in an A-framed vertical unit. Three growing media were tested: coir pith (M0), Rockwool (M1), and a 1:1 mix of coir pith and vermiculite (M2). Various combinations of water-soluble fertilizers [Ca (NO3)2, MAP, and SOP] were used for each crop’s nutrient recipe preparation. Optimal yields were achieved when palak were grown in a coir pith and vermiculite mix with nutrient concentrations of 60:50:60 ppm. Despite high yields, green leafy vegetables face rapid spoilage and storage challenges. The study examined factors affecting post-harvest quality, including storage conditions (ambient at 35 ± 5°C, refrigerated at 5 ± 5°C), packing substrates (low-density polyethylene, high-density polyethylene covers), and gas compositions with modified atmosphere packaging. Results showed that refrigerated storage with low-density polyethylene packing and a gas composition of 6% O2, 5% CO2, and 89% N2 (G2) resulted in the least deterioration in physiological attributes and overall visual quality. This study highlights the potential of vertical farming technology, precise nutrient management, and advanced post-harvest techniques for sustainable production and preservation of green leafy vegetables to meet our nation’s nutritional security needs.

The aim of this article is to review applications of modified atmosphere packaging (MAP) in poultry meat. As well as, its effects on the qualitative characteristics and shelf-life stability. Packaging is a harmonized rule of preparing the product for transportation, dissemination, retail, and end-use to ensure safe delivery. MAP is modern packaging that includes air removal (78% N2, 21% O2, and 3% CO2 gas) from inside the casings and replacing them with a single gas or a mixture of gases. The atmosphere with a high concentration of O2 by 80 % leads to off-oxygenating the dye and keeps it from deteriorating on the surface of the meat. O2 causes oxidation of fat and protein, and decreases the quality of meat. The CO2 gas concentration and the casings composition significantly affect the change in the meat pH value. The decrease in oxygen in the packaging alters the meat colour from red to purple to convert the Oxymyoglobin to Deoxymyoglobin. Moreover, the consumer rejects this type of meat with a myoglobin tint. The colour stability using MAP has improved, and the Metmyoglobin configuration rate has decreased. MAP gave less moisture loss. The total and psychrophile bacterial populations in the poultry meat treated with MAP decreased and increased with the progress of storage periods. The TBA value, the peroxide value, and the fatty acid percentage decreased by using the MAP. MAP can be a part of Hurdle's technique to prolong the chicken meat shelf life.

The aim of this article is to review applications of modified atmosphere packaging (MAP) in poultry meat. As well as, its effects on the qualitative characteristics and shelf-life stability. Packaging is a harmonized rule of preparing the product for transportation, dissemination, retail, and end-use to ensure safe delivery. MAP is modern packaging that includes air removal (78% N2, 21% O2, and 3% CO2 gas) from inside the casings and replacing them with a single gas or a mixture of gases. The atmosphere with a high concentration of O2 by 80 % leads to off-oxygenating the dye and keeps it from deteriorating on the surface of the meat. O2 causes oxidation of fat and protein, and decreases the quality of meat. The CO2 gas concentration and the casings composition significantly affect the change in the meat pH value. The decrease in oxygen in the packaging alters the meat colour from red to purple to convert the Oxymyoglobin to Deoxymyoglobin. Moreover, the consumer rejects this type of meat with a myoglobin tint. The colour stability using MAP has improved, and the Metmyoglobin configuration rate has decreased. MAP gave less moisture loss. The total and psychrophile bacterial populations in the poultry meat treated with MAP decreased and increased with the progress of storage periods. The TBA value, the peroxide value, and the fatty acid percentage decreased by using the MAP. MAP can be a part of Hurdle's technique to prolong the chicken meat shelf life. [ABSTRACT FROM AUTHOR]

Aqueous foam is a dispersion of gas in liquid, where the liquid acts as the continuous phase and the gas is separated by thin liquid films stabilized by a surfactant. Foam injection is a widely used technique in various applications, including CO2 sequestration, enhanced oil recovery, soil remediation, etc. Surfactant-alternating-gas (SAG) is a preferred approach for foam injection, and injectivity plays a vital role in determining the efficiency of the SAG process. Different gases can be applied depending on the process requirements and availability. However, the underlying mechanisms by which gas composition impacts injectivity are not yet fully understood. In this work, the effect of gas composition on fluid behavior and injectivity in a SAG process was investigated using three gases: N2, CO2, and Kr. Our observations revealed that gas solubility in liquid was key for the formation and evolution of liquid fingers, and therefore was very important for liquid injectivity. A lower gas solubility in liquid led to a slower increase in surfactant solution injectivity. In addition, the development of surfactant solution injectivity took significantly longer when the surfactant solution was partially pre-saturated compared to when it was unsaturated. Additionally, the propagation of the collapsed-foam bank during gas injection was accelerated when the gas had a greater solubility in water. [ABSTRACT FROM AUTHOR]

Cold plasma (CP) is a non-thermal preservation technology that has been successfully used to decontaminate and extend the shelf life of aquatic products. However, the preservation effect of CP treatment is determined by several factors, including voltage, time, and gas compositions. Therefore, this study aimed to investigate the effects of gas composition (GasA: 10% O2, 50% N2, 40% CO2; GasB: air; GasC: 30% O2, 30% N2, 40% CO2) on the lipid oxidation of tilapia fillets treated after CP treatment. Changes in the lipid oxidation values, the percentages of fatty acids, and sensory scores were studied during 8 d of refrigerator storage. The results showed that the CP treatment significantly increased all the primary and secondary lipid oxidation values measured in this study, as well as the percentages of saturated fatty acids, but decreased the percentages of unsaturated fatty acids, especially polyunsaturated fatty acids. The lipid oxidation values were significantly increased in the GasC-CP group. After 8 d, clearly increased percentages of saturated fatty acids, a low level of major polyunsaturated fatty acids (especially linoleic (C18:2n-6)), and a decrease in the percentages of eicosapentaenoic acid (C20:5n-3) and docosahexaenoic acid (C22:6n-3) were found in GasC-CP; that is, the serious oxidation of lipids was found in the high O2 concentration group. In addition, the sensory score was also lower than that of the hypoxia CP group. Therefore, high O2 concentrations can enhance lipid oxidation and the changes in the fatty acid concentration. Controlling the O2 concentration is reasonable to limit the degree to which lipids are oxidized in tilapia after the in-package CP treatment. [ABSTRACT FROM AUTHOR]

The results of experimental studies of the process of electroslag remelting of titanium in a chamber furnace at different values of pressure in the melting area, from vacuum to excess pressure, are given. Experiments were carried out during the melting of ingots with a diameter of 85 and 105 mm from titanium alloys VT1-0 and VT22 using fluoride-chloride flux AN-T4. The pressure of the inert gas in the furnace chamber was varied from 20 to 300 kPa. It is shown that in the entire studied range of pressures, the electroslag process proceeded stably with the formation of ingots with a high-quality side surface and a dense structure, without pores, slag inclusions and other internal defects. Experimental data on the effect of pressure in the melting area on the gas composition and structure of titanium ingots are given. The possibility of reducing the hydrogen content in titanium alloys by carrying out the electroslag process under vacuum conditions is shown. It was also established that the VT1-0 titanium ingot, melted under vacuum conditions, is characterized by a larger grain size compared to the ingot obtained at excess pressure. [ABSTRACT FROM AUTHOR]

Green hydrogen can be produced by consuming surplus renewable generations. It can be injected into the natural gas networks, accelerating the decarbonization of energy systems. However, with the fluctuation of renewable energies, the gas composition in the gas network may change dramatically as the hydrogen injection fluctuates. The gas interchangeability may be adversely affected. To investigate the ability to defend the fluctuated hydrogen injection, this paper proposes a gas interchangeability resilience evaluation method for hydrogen-blended integrated electricity and gas systems (H-IEGS). First, gas interchangeability resilience is defined by proposing several novel metrics. Then, A two-stage gas interchangeability management scheme is proposed to accommodate the hydrogen injections. The steady-state optimal electricity and hydrogen-gas energy flow technique is performed first to obtain the desired operating state of the H-IEGS. Then, the dynamic gas composition tracking is implemented to calculate the real-time traveling of hydrogen contents in the gas network, and evaluate the time-varying gas interchangeability metrics. Moreover, to improve the computation efficiency, a self-adaptive linearization technique is proposed and embedded in the solution process of discretized partial derivative equations. Finally, an IEEE 24 bus reliability test system and Belgium natural gas system are used to validate the proposed method.

This study evaluated the effects of gas composition in kimchi packaging on kimchi quality. Completely sealed packaging without gas inflow/outflow during fermentation (S1), packaging allowing gas outflow (S2), and packaging allowing gas inflow and outflow (S3) were used. Microbial composition analysis, volatile compound content analysis, and sensory evaluation were performed to determine the differences in kimchi quality among samples. Metabolites were examined using principal component analysis. Gas composition analysis showed that the ratio of CO2 increased during the storage period in S1, the ratio of nitrogen and CO2 contents was constant in S2, and the ratio of oxygen was significantly higher in S3. No significant differences in the lactic acid bacteria number were observed. However, coliforms were only detected in S3, and yeast and mold proliferated faster in S3 than in S2 or S1. The main compounds detected in S1 and S2 were alcohols, whereas those in S3 were esters such as β-phenethyl acetate produced by yeast. Sensory evaluation showed that S3 had the lowest odor, taste, and overall scores, whereas S2 had the highest. In conclusion, the gas composition inside the kimchi package greatly affects the quality of kimchi. Our findings provide important data that can be useful in the manufacture of commercial kimchi. [ABSTRACT FROM AUTHOR]

Gasification of organic waste represents one of the most effective valorization pathways for renewable energy and resources recovery, while this process can be affected by multi-factors like temperature, feedstock, and steam content, making the product's prediction problematic. With the popularization and promotion of artificial intelligence such as machine learning (ML), traditional artificial neural networks have been paid more attention by researchers from the data science field, which provides scientific and engineering communities with flexible and rapid prediction frameworks in the field of organic waste gasification. In this work, critical parameters including temperature, steam ratio, and feedstock during gasification of organic waste were reviewed in three scenarios including steam gasification, air gasification, and oxygen-riched gasification, and the product distribution and involved mechanism were elaborated. Moreover, we presented the details of ML methods like regression analysis, artificial neural networks, decision trees, and related methods, which are expected to revolutionize data analysis and modeling of the gasification of organic waste. Typical outputs including the syngas yield, composition, and HHVs were discussed with a better understanding of the gasification process and ML application. This review focused on the combination of gasification and ML, and it is of immediate significance for the resource and energy utilization of organic waste. [ABSTRACT FROM AUTHOR]

Although many studies focusing on the causes of the abnormal concentration of different coalbed methane (CBM) compositions were conducted, the unified standard for defining the abnormal concentration of different components is still missed. To clarify the distribution of CBM composition in China and determine the concentration boundary of abnormal composition, based on 4654 measured and collected gas data from coalfield exploration boreholes and CBM wells, which meet the lower limit of CBM reserves estimation in the standard DZ/T 0216—2020. The statistical results showed that the average concentration of CH4, C2+, CO2, and N2 in CBM in China were 91.82%、0.85%、2.04% and 5.19%, respectively, and the proportion of CH4 concentration greater than 90% was 77.44%. It can be defined as abnormal gas composition meeting any of the following four conditions: the C2+ concentration is greater than 5%; the N2/CO2 concentration is greater than 10%; the harmful gas concentration exceeds the upper limit of coal mine safety regulations; the rare gas concentration exceeds that in air. Based on the definition, the results showed that the proportion of C2+ concentration greater than 5% is 5.16% in China and the CO2 concentration greater than 10% accounts for 4.00%. Moreover, the proportion of N2 concentration greater than 10% is 13.26%, and the maximum helium concentration in the southern Junggar Basin reaches 0.97%. Based on the above results, the causes of abnormal CBM composition/concentrations are summarized as the stages of coalification, the differences in coal petrography, sulfate reduction effect, ancient weathering crust, and the migration of gas outside the source. In the subsequent CBM exploration, it is suggested to determine the total gas composition; conduct the study focusing on the gas desorption in coal reservoirs with abnormal CO2 and N2 concentration; determine the helium source rock of coal measures and discuss the law of hydrocarbon helium source and reservoirs to analyze the interaction between organic gas and inorganic gas of coal measures; comprehensively clarify the transformation of geological structure, groundwater flow, microorganism and magmatic activity on gas components to reveal the evolution mechanism of migration, enrichment, and preservation of different gas components in different regions. The results provide a guide for CBM exploitation, coal mine safety production, and CBM utilization.

The study aimed to investigate the valve and geothermal microclimate systems' impact on microclimate indicators in farrowing rooms. In farrowing rooms, where the valve type of ventilation was installed, the temperature in the farrowing room in summer and autumn exceeded the norm by 3.90 and 1.60 °C, respectively. The amplitude of the average values of the annual temperature dynamics at all these measurement points was higher at using valve-type ventilation relative to geothermal, which provided a constant temperature during the year. Humidity during all seasons of the year was optimal with the use of both microclimate systems, but in summer and autumn, it was probably higher during using geothermal ventilation. The content of carbon dioxide reached its highest values in the autumn months with the use of both systems to create a microclimate, but without exceeding the norm. At the same time, its content was probably higher in the summer months in the room for keeping pregnant sows with the geothermal type of ventilation by 400 ppm or 50% (P

In order to explore the relationship between storage conditions and the quality changes of high-quality indica rice, the high-quality indica rice “Fengyou 22” samples were stored at 4 storage temperatures (15, 20, 25 and 30 ℃) and 3 moisture contents (13.5%, 14.5% and 15.5%) and 2 gas composition (modified atmosphere with nitrogen, non-modified atmosphere) simulated storage for 360 d, and the yellow rice content, germination rate, electrical conductivity, α-amylase activity, fatty acid value, gel consistency, straight chain starch content, rice soup solids, iodine blue value and rice hardness, rice viscosity, rice balance, rice elasticity, appearance score, taste score, comprehensive score and other indicators were regularly determined. The results showed that the higher the storage temperature and the higher the moisture content, the more obvious the quality changed; under the same condition of storage temperature and moisture content, nitrogen storage had the effect of delaying the quality change. The principal component analysis method was used to analyze the 16 indicators, and 5 principal component factors with a cumulative contribution rate of 81.055% were obtained through dimensionality reduction. Representative quality indicators were chosen from the indicators with larger positive eigenvalues in each principal component, which were germination rate, electrical conductivity, iodine blue value and amylose content. The correlation analysis of the four characteristic indexes with storage temperature, moisture content and gas composition showed that storage temperature had the greatest influence on the characteristic indexes of high-quality indica rice, followed by moisture content then gas composition.

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Current standards and procedures for parametric load release are based on technologies from the 1960s, are consensus based and are often not supported by scientific evidence. In the literature, however, methods are reported which can fairly easily be implemented and improve current parametric load release for steam sterilization. To implement an improved parametric load release procedure, exceeding the current standards and methods for monitoring steam sterilization processes. Implementation of the procedure should be feasible for all interested end-users. The steam sterilization criteria specified in the literature were used to define a set of steam sterilization conditions. A search for commercially available devices and methods which can assess these conditions parametrically was performed. After selecting a method, a field study was carried out. Two devices were identified which could be used to improve parametric load release after a steam sterilization process. A comparison showed that a permanently installed device which – independent from the sterilizer – measures the temperature, the steam composition in the chamber and the time for every steam sterilization process, offers the most advantages. The selected method has been implemented and tested on 51 steam sterilizers. The selected method makes steam sterilization safer, more sustainable, and more cost effective. It can be implemented by all interested end-users. [ABSTRACT FROM AUTHOR]

Cold plasma (CP) is a non-thermal preservation technology that has been successfully used to decontaminate and extend the shelf life of aquatic products. However, the preservation effect of CP treatment is determined by several factors, including voltage, time, and gas compositions. Therefore, this study aimed to investigate the effects of gas composition (GasA: 10% O2, 50% N2, 40% CO2; GasB: air; GasC: 30% O2, 30% N2, 40% CO2) on the lipid oxidation of tilapia fillets treated after CP treatment. Changes in the lipid oxidation values, the percentages of fatty acids, and sensory scores were studied during 8 d of refrigerator storage. The results showed that the CP treatment significantly increased all the primary and secondary lipid oxidation values measured in this study, as well as the percentages of saturated fatty acids, but decreased the percentages of unsaturated fatty acids, especially polyunsaturated fatty acids. The lipid oxidation values were significantly increased in the GasC-CP group. After 8 d, clearly increased percentages of saturated fatty acids, a low level of major polyunsaturated fatty acids (especially linoleic (C18:2n-6)), and a decrease in the percentages of eicosapentaenoic acid (C20:5n-3) and docosahexaenoic acid (C22:6n-3) were found in GasC-CP; that is, the serious oxidation of lipids was found in the high O2 concentration group. In addition, the sensory score was also lower than that of the hypoxia CP group. Therefore, high O2 concentrations can enhance lipid oxidation and the changes in the fatty acid concentration. Controlling the O2 concentration is reasonable to limit the degree to which lipids are oxidized in tilapia after the in-package CP treatment.

Aqueous foam is a dispersion of gas in liquid, where the liquid acts as the continuous phase and the gas is separated by thin liquid films stabilized by a surfactant. Foam injection is a widely used technique in various applications, including CO2 sequestration, enhanced oil recovery, soil remediation, etc. Surfactant-alternating-gas (SAG) is a preferred approach for foam injection, and injectivity plays a vital role in determining the efficiency of the SAG process. Different gases can be applied depending on the process requirements and availability. However, the underlying mechanisms by which gas composition impacts injectivity are not yet fully understood. In this work, the effect of gas composition on fluid behavior and injectivity in a SAG process was investigated using three gases: N2, CO2, and Kr. Our observations revealed that gas solubility in liquid was key for the formation and evolution of liquid fingers, and therefore was very important for liquid injectivity. A lower gas solubility in liquid led to a slower increase in surfactant solution injectivity. In addition, the development of surfactant solution injectivity took significantly longer when the surfactant solution was partially pre-saturated compared to when it was unsaturated. Additionally, the propagation of the collapsed-foam bank during gas injection was accelerated when the gas had a greater solubility in water.

Yutai Sag is a Mesozoic synsedimentary fault basin. It is characterized by much fault intersection and massive Ordovician carbonate rock in the deep, which indicates a good prospect of geothermal development. To study the characteristics of carbonate thermal reservoirs in this fault basin and evaluate its geothermal resource potential, a hole with a depth of 2 309.31 m was drilled in Yutai Sag. Through comprehensive logging, productivity testing, hydrochemical analysis, gas composition analysis, and geothermal water 14C age determination, the sources and supply of thermal fluid, heat source storage, and ion migration in the interior of the basin are analyzed.The result shows that the temperature anomaly presented in the geothermal well temperature curve and the fault position characterized by many fractures are consistent, indicating the source direction of geothermal water.The geothermal water with high content of Cl- and Na- is related to halite dissolution. The apparent age of geothermal water is 43.5 ka BP near the confluence of faults in the southeastern Yutai Sag, and the corrected age is 10.752 ka BP which is from the late Quaternary Pleistocene to the early Holocene.The study shows that there are relatively active or young geological structures in Yutai Sag, which are one of the thermal sources of thermal reservoirs. The recoverable geothermal resources of the Ordovician thermal reservoir in the area are approximately 2.12×109 GJ, equivalent to 7.27×107 t of standard coal, implying great resource potential and good prospects for development and utilization.

The aim of this study is to investigate the influence of biomass particle size on the torrefaction characteristics under different torrefaction temperatures and times. Paulownia wood with particle sizes ranging from 12 to <0.3 mm was selected. It was torrefied at 260 and 290 °C in a fixed-bed reactor for 30–90 min. The results showed that biomass particle size did affect the product's evolution during biomass torrefaction. With the decrease in particle size from 12 to <0.3 mm, the yield of the solid product decreased by 5.41 and 3.54 wt.%, the yield of the liquid product increased by 5.87 and 3.25 wt.%, and the yield of the gas product changed insignificantly, at 260 and 290 °C, respectively. Comparatively, torrefaction temperature had a more significant effect on the composition of gas products than particle size and torrefaction time. At lower temperatures, decarboxylation reactions dominated in the torrefaction process with more CO2 produced. However, at higher temperatures, decarbonylation reactions were significantly strengthened with more CO generated. The contents of CO2 and CO could account for more than 98 vol% of the product gas. The influence of particle size on the chemical composition of the solid product was much smaller than that of torrefaction temperature and time, but the energy yield of the solid product decreased with the decrease in particle size. The increase in torrefaction temperature and time could significantly increase the C content in the solid product while reducing its O content. It is recommended to use a relatively higher temperature (e.g., 290 °C) for the torrefaction of large particle biomass, as it could significantly reduce the impact of particle size on the torrefaction process and reduce the torrefaction time. [ABSTRACT FROM AUTHOR]

Blast furnace ironmaking is one of the most serious carbon dioxide emission processes. To reduce energy consumption and CO2 emissions, fluidized bed ironmaking technology with hydrogen as a reducing agent has attracted more and more attention. An inclined agitator was added to the fluidized bed reactor to address the sticking issue in the conventional fluidized bed ironmaking process. In this research, numerical simulation was used to examine the impacts of reducing gas composition and agitation speed on the gas-solid fluidization quality in the cold fluidization of iron ore powder in the fluidized bed with an inclined agitator. The results indicate that the fluidization effect of iron ore powder is better when the volume ratios of H2 to CO and H2 to N2 are 1:1. Under the intensive shear action of the agitator, the standard deviation of pressure drop constantly decreases with the increase in agitation speed, and the decreasing range is smaller and smaller. The fluidization state of the iron ore powder particles in the bed stabilized when the agitation speed reached 160 rpm. [ABSTRACT FROM AUTHOR]

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the dehydrogenation of formic acid, catalyst has a great influence on the composition and formation rate of gaseous products. However, the hydrogen used in fuel cells has strict requirements on the content of carbon monoxide impurities. Therefore, it is very important to study the relationship between catalyst components and their synergistic effects and the composition of gaseous products. The role of Pd-Cr bimetallic nanoparticles supported on amino modified Cr-based metal-organic framework catalyst (Pd4Cr6@(NH2)M-MOF(Cr)) in the formic acid dehydrogenation was explored through comparative experiments and catalyst characterization. Results show that both Cr-based metal-organic framework (MOF(Cr)) and amino-modified Cr-based metal-organic framework ((NH2)M-MOF(Cr)) have no effect on promoting the generation of gaseous products. The presence of Cr and NH2 groups in Pd4Cr6@(NH2)M-MOF(Cr) greatly improves the formation rate of H2 and CO2 products, the gas production rate of Pd4Cr6@(NH2)M-MOF(Cr) is 2.89 times that of Pd4@(NH2)M-MOF(Cr), and the gas production rate of Pd4Cr6@(NH2)M-MOF(Cr) is 6.26 times of Pd4Cr6@MOF(Cr). However, the formation rate of H2 increases more in the presence of Cr. Synergy of Pd-Cr and Pd-NH2 in the Pd4Cr6@(NH2)M-MOF(Cr) catalyst promotes CO formation. [ABSTRACT FROM AUTHOR]

Background: Fire models use pyrolysis data from ground samples and environments that differ from wildland conditions. Two analytical methods successfully measured oxidative pyrolysis gases in wind tunnel and field fires: Fourier transform infrared (FTIR) spectroscopy and gas chromatography with flame-ionisation detector (GC-FID). Compositional data require appropriate statistical analysis. Aims: To determine if oxidative pyrolysis gas composition differed between analytical methods and locations (wind tunnel and field). Methods: Oxidative pyrolysis gas sample composition collected in wind tunnel and prescribed fires was determined by FTIR and GC/FID. Proportionality between gases was tested. Analytical method and location effects on composition were tested using permutational multivariate analysis of variance and the Kruskal–Wallis test. Key results: Gases proportional to each other were identified. The FTIR composition differed between locations. The subcomposition of common gases differed between analytical methods but not between locations. Relative amount of the primary fuel gases (CO, CH4) was not significantly affected by location. Conclusions: Composition of trace gases differed between the analytical methods; however, each method yielded a comparable description of the primary fuel gases. Implications: Both FTIR and GC/FID methods can be used to quantify primary pyrolysis fuel gases for physically-based fire models. Importance of the trace gases in combustion models remains to be determined. Oxidative pyrolysis gases were measured in a wind tunnel and small prescribed burns using two analytical methods. Gas composition measured by FTIR spectroscopy differed between wind tunnel and field fires. The relative amount of the primary fuel gases (CO, CH4) was not significantly affected by fire location. (This paper is part of a Special Issue that includes papers on research presented at the IX International Conference on Forest Fire Research, Coimbra, Portugal, November 2022.) [ABSTRACT FROM AUTHOR]

• This study presents a quantitative measurement of the metal transfer frequency of a metal-cored wire under various argon-CO2 shielding gas mixtures (5, 10, 15, 20, 25,50, and 100%) and compares it with that of a solid wire. • Through shadowgraph observation and arc plasma investigation, the mechanism of the effect of CO2 concentration on the metal transfer of the metal-cored wire was proposed. • The metal transfer frequency of solid wire was monotonically decreased when CO 2 content increased, while that of the metal-cored wire reached a peak at a critical CO 2 concentration of 15%. • The equilibrium between arc attachment and the length of unmelted flux at the wire tip was found to influence droplet detachment behavior. Both factors were notably influenced by the CO 2 content, with equilibrium being attained at a CO 2 concentration of 15%. Metal transfer frequencies in a gas metal arc welding process with a metal-cored wire were quantitatively measured for the first time as a function of the CO 2 content (i.e., 5, 10, 15, 20, 25, 50, and 100%) in argon-CO 2 shielding gas mixtures at welding currents of 220, 250, and 280 A, and the results were compared with those of a solid wire. As a result, the metal transfer frequency of solid wire was monotonically decreased with the CO 2 content owing to an increase in the arc pressure, which prevented droplet detachment. However, the metal transfer frequency of the metal-cored wire presented a maximum value at 15% CO 2 under all the current levels. The transfer behavior was supposed to depend on the relation between the arc attachment position and the tip of the unmelted flux position inside the cored wire. When the CO 2 concentration was low, the arc was attached higher than the unmelted flux, causing the electromagnetic force to be ineffective in droplet separation. When the CO 2 concentration increased slightly, the arc was moved downward to the tip of the unmelted flux. That tendency temporarily facilitated the neck formation at the wire tip due to enhanced electromagnetic force flowing through the molten metal on the wire tip. Nevertheless, when the CO 2 content increased over a critical value, the arc pressure became a dominant factor to hinder the droplet detachment, which caused a decrease in transfer frequency. Consequently, the metal transfer frequency of metal-cored wire became maximum at 15% CO 2. [ABSTRACT FROM AUTHOR]

To meet the target of reducing greenhouse gas emissions, hydrogen as a carbon-free fuel is expected to play a major role in future energy supplies. A challenge with hydrogen is its low density and volumetric energy value, meaning that large tanks are needed to store and transport it. By injecting hydrogen into the natural gas network, the transportation issue could be solved if the hydrogen–natural gas mixture satisfies the grid gas quality requirements set by legislation and standards. The end consumers usually have stricter limitations on the gas quality than the grid, where Euromot, the European association of internal combustion engine manufacturers, has specific requirements on the parameters: the methane number and Wobbe index. This paper analyses how much hydrogen can be added into the natural gas grid to fulfil Euromot's requirements. An average gas composition was calculated based on the most common ones in Europe in 2021, and the results show that 13.4% hydrogen can be mixed with a gas consisting of 95.1% methane, 3.2% ethane, 0.7% propane, 0.3% butane, 0.3% carbon dioxide, and 0.5% nitrogen. The suggested gas composition indicates for engine manufacturers how much hydrogen can be added into the gas to be suitable for their engines. [ABSTRACT FROM AUTHOR]

Corrosion by metal dusting causes problems in various industries that process carbonaceous gases. Recently, the chromium‐ and aluminum‐rich Ni‐based Alloy 699 XA was introduced as a material with high resistance against metal dusting attacks. In this study, the metal dusting degradation of Alloy 699 XA and model alloys was investigated. In the model alloys, the aluminum, chromium, and iron contents were varied to analyze the role of each element systematically. Alloy 602 CA was included as a reference material. It was found that the alloys with the highest chromium and aluminum contents (30 and 2–3 wt%, respectively) showed the highest resistance against metal dusting. Also, the limited addition of iron enhanced the aluminum activity and thereby promoted the formation and maintenance of an aluminum‐rich oxide scale. This effect at low iron levels is contrary to the negative impact of iron at higher levels, which typically leads to an increased metal dusting susceptibility. Exposure tests were performed with two gas mixtures having similar compositions, but different carbon activities. It was found that both gases had a similar aggressiveness regarding metal dusting attacks. [ABSTRACT FROM AUTHOR]

This study explores the synergistic effects of gas composition and electric field modulation on beetroot seed germination using dielectric barrier discharge (DBD) plasma. The investigation initially focuses on the impact of air plasma exposure on germination parameters, varying both voltage and treatment duration. Subsequently, the study examines how different gas compositions (argon, nitrogen, oxygen, and carbon dioxide) affect germination outcomes under optimal air plasma conditions. Results indicate that plasma treatment significantly enhances germination rates and seedling growth relative to untreated controls. Notably, plasma exposure alters seed surface morphology and chemistry, increasing roughness, porosity, and hydrophilicity due to the formation of new polar functional groups. The highest germination rate (a 54.84 % increase) and germination index (a 40.11 % increase) were observed at the lowest voltage and shortest duration, whereas higher voltages and prolonged exposure reduced germination, likely due to oxidative stress. Among the tested gas environments, air plasma was most effective in enhancing water uptake and electrical conductivity, while oxygen plasma resulted in the highest germination index and marked improvements in root and shoot length. Conversely, carbon dioxide plasma treatment exhibited inhibitory effects on both germination and subsequent growth metrics. The results highlight the potential of DBD plasma technology to enhance agricultural productivity by optimizing seed germination and early growth. The study emphasizes the importance of precise parameter tuning, particularly gas composition and plasma exposure conditions, to maximize benefits while minimizing adverse effects, offering a refined approach to seed priming in agricultural practices., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors. Published by Elsevier Ltd.)

The phase structures, microstructures, wear properties, and corrosion resistance of plasma nitrided and plasma oxynitrided 4140 steel were studied. The plasma nitriding was conducted on a mixture of nitrogen and hydrogen at 520 °C. Additional oxygen in the form of plain air was added during oxynitriding treatment in a fixed ratio of nitrogen and hydrogen at 520 °C. The influences of gas composition on properties of the nitrided layer and oxynitrided layer were investigated using an optical microscope, scanning electron microscope, profilometer, X-ray diffractometer, X-ray photoelectron spectroscopy, Raman microscope, micro and nano-indenters, a tribometer, and potentiodynamic polarization testing. Results of tests demonstrate that an iron oxide layer with nanocrystalline Fe2–3N phase distributed forms on the surface of plasma oxynitrided specimens. Oxygen addition leads to different phase compositions, microstructures, and thicknesses of surface layer, which result in differences in mechanical, wear, and corrosion properties of specimens. The plasma oxynitrided specimen with optimal properties was obtained at a certain gas composition (N:H:O = 1:1:0.175), which shows better wear property and corrosion resistance than plasma nitrided specimen.

In this paper, in order to understand the development process and influencing factors of coal underground gasification, taking the two-dimensional underground gasification area of the plane as the simulation object, the characteristics of the multi-physical field coupling process of exudate mass heat transfer and combustion gasification reaction in the process of horizontal coal seam underground gasification are analyzed, and a two-dimensional mathematical model of thermal-hydrological-mechanical-chemical coupling of a porous medium is established. The temperature distribution of coal rock from the gasification point, the distribution of gas water vapor pressure and stress-strain, the temperature contour distribution of fractured coal rocks of different densities of heterogeneity, and the influence of different water-oxygen ratios and different fractured coal rocks on the gas components generated by the gasification reaction were studied. The results show that the tensile damage caused by the tensile strain volume expansion of the coal underground gasification center, the shear damage caused by the compression of the edge compressive strain volume, and the temperature conduction rate decrease with the increase in the coal rock fracture, but in the heterogeneous coal rock, the greater the fracture density, the faster the temperature conduction rate, which has a certain impact on the gasification combustion reaction. The ratio of CO2, H2 and CO in the case of simulating that the water-to-oxygen ratio is 1:2, 1:1, and 2:1 is 1:0.85:0.73, 1:1.1:0.97, and 1:1.76:1.33, respectively. At a water-oxygen ratio of 2:1, the concentration ratio is the most ideal, and the main gases, CO, CO2, and H2, are 32%, 21%, and 37%. Furthermore, the reaction rate increases with the increase of fracture density. The gas component concentration simulated in this paper has good consistency with the results of the previous experimental data, which has important guiding significance for the underground coal gasification project. [ABSTRACT FROM AUTHOR]

The study aimed to investigate the valve and geothermal microclimate systems' impact on microclimate indicators in farrowing rooms. In farrowing rooms, where the valve type of ventilation was installed, the temperature in the farrowing room in summer and autumn exceeded the norm by 3.90 and 1.60 °C, respectively. The amplitude of the average values of the annual temperature dynamics at all these measurement points was higher at using valve-type ventilation relative to geothermal, which provided a constant temperature during the year. Humidity during all seasons of the year was optimal with the use of both microclimate systems, but in summer and autumn, it was probably higher during using geothermal ventilation. The content of carbon dioxide reached its highest values in the autumn months with the use of both systems to create a microclimate, but without exceeding the norm. At the same time, its content was probably higher in the summer months in the room for keeping pregnant sows with the geothermal type of ventilation by 400 ppm or 50% (P <0.01). The ammonia content tended to increase in the autumn months in both farrowing rooms, but reached its highest values in the fall, remaining, however, within normal limits. The hydrogen sulfide content did not exceed the optimal values for both farrowing rooms during all seasons without a statistically significant difference between different types of ventilation. In the farrowing rooms where the geothermal ventilation system was used, the highest H2S content was in the winter months, amounting to 3.59 ppm, which is 0.96 ppm or 26.81% (P <0.001) higher than in spring, 0.83 ppm or 23.29% (P <0.001) higher than in summer and 0.26 ppm or 7.44% (P <0.05) higher than in spring. [ABSTRACT FROM AUTHOR]

A number of significant parameters such as gasification temperature, dimensions of gasifier, nature of feedstock, position of the components, particle size of feedstock, inlet air temperature, equivalence ratio, and type of gasifier highly influence the yield and characteristics of producer gas (PG). However, structural design of the air nozzle and temperature of the inlet air have received significant attention in enhancing the composition of producer gas and its gasification efficiency. In this study, species transport model of the numerical simulation had been selected to analyze the performance parameters of a gasifier for the air nozzle's angle and inlet air temperature from 0 to 60° and 27 to 627 °C, respectively. Rice husk was used as the feedstock. For the accuracy of simulation, the results were compared with an experimental study. The combustible gas composition, higher heating value of PG was analyzed in both numerical and experimental studies; furthermore, the prevailing temperature inside the gasifier was also keenly observed and recorded. Among the various nozzle positions, the composition of CO, H2, and CH4 in the producer gas was better at 45° nozzle inclination with 627 °C inlet air temperature; moreover, the composition of the gaseous compounds in the PG were found as 19 to 23%, 13 to 15%, and 2 to 3% respectively. For the above-mentioned conditions of nozzle inclination and inlet air temperature, the calorific value of producer gas was in the range of 4–6 MJ/Nm3. The temperature distribution in the combustion, reduction, pyrolysis, and drying zones was in the range of 1000–1200 °C, 600–700 °C, 300–420 °C, and 200–300 °C, respectively. [ABSTRACT FROM AUTHOR]

Smoking is an important process unit operation used for preservation, as well as flavor, color and texture modifications of many foods. Currently, wood pyrolysis temperatures in industrial smoke generators cannot be systematically adjusted, thus process outcomes can only be controlled by varying smoke exposure time and environmental conditions in the adjacent product chamber. In this study, we investigated changes in pyrolysis temperature and flue gas composition in a redesigned smoldering smoke generator in which air intake could be adjusted. Air volume flow rates were set at 5.6 m³/h, 7.7 m³/h, 10.2 m³/h, 12.1 m³/h and 15.7 m³/h. Ember bed temperatures and flue gas compositions were determined as a function of these rates. Mean ember bed temperatures were affected by both the air volume flow rate as well as the smoke generation time i.e. a higher volume flow rate and/or a longer smoke generation time increased mean ember bed temperatures. Increasing air volume flow rates also led to decreases in oxygen concentration and increases in carbon monoxide concentration. Furthermore, frequential supply of fresh wood chips from the storage container to the site of the pyrolysis led to an increase in oxygen concentration, which decreased again upon ignition. The results suggest that - contrary to current practice - smoke composition and amount may be altered by controlling the pyrolysis process itself, thereby providing new possibilities to modify quality attributes of smoked foods such as meat, seafood or dairy products. • Ember bed temperatures and flue gas were evaluated in a controlled smoldering process. • Temperature profiles vary within ember bed. • Unstable ember bed temperatures during ignition phase. • Contrary behavior from CO (increase) and O 2 (decrease). [ABSTRACT FROM AUTHOR]

Copyright of MESO is the property of Zadruzna Stampa D.D. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Composition of pyrolysis gases for wildland fuels is often determined using ground samples heated in non-oxidising environments. Results are applied to wildland fires where fuels change spatially and temporally, resulting in variable fire behaviour with variable heating. Though historically used, applicability of traditional pyrolysis results to the wildland fire setting is unknown. Pyrolytic and flaming combustion gases measured in wind tunnel fires and prescribed burns were compared using compositional data techniques. CO2 was dominant in both. Other dominant gases included CO, H2 and CH4. Relative amounts of CO, CO2 and CH4 were similar between fire phases (pyrolysis, flaming combustion); relatively more H2 was observed in pyrolysis samples. All gas log-ratios with CO2 in pyrolysis samples were larger than in flaming combustion samples. Presence of live plants significantly affected gas composition. A logistic regression model correctly classified 76% of the wind tunnel samples as pyrolysis or flaming combustion based on gas composition. The model predicted 60% of the field samples originated from pyrolysis. Fire location (wind tunnel, field) and fire phase affected gas composition. The compositional approach enabled analysis and modelling of gas compositions, producing results consistent with the basic characteristics of the data. [ABSTRACT FROM AUTHOR]

In this paper, the packed bed dielectric barrier discharge (DBD) with needle-plate electrode configuration is presented to study the effects of electrical parameters, such as pulse duration and pulse rising and falling time, on discharge characteristics under air and nitrogen. The waveforms of the voltage and the discharge current, discharge evolution images, and the emission spectral of N2 (C3Пu → B3Пg) and N2+ (B2Σu+ → X2Σg+) are collected to investigate the discharge current, as well as the spatial distribution of the discharge modes and the reactive species in the packed bed reactor specifically. It is found that the pulse duration and pulse rising and falling time can regulate the discharge current. Firstly, increasing the pulse duration and the pulse rising and falling time can both increase the discharge duration. Secondly, the peak value of the discharge current has an obvious increasing trend with the pulse duration. Finally, the discharge start time can be delayed by increasing the pulse rising and falling time. A bright discharge channel is distributed at the top of the reactor, while the discharge is diffused at the bottom of the reactor. The generation of N2+ (B2Σu+) tends to depend on the existence of the streamer channel, and N2 (C3Пu) can be generated in the entire discharge area. In addition, the discharge operated in pure nitrogen can reach higher current values, a stronger discharge intensity, and longer existence time for the reactive species than in the air. [ABSTRACT FROM AUTHOR]

The composition of hydrocarbons (HCs) generated in the course of transformation of the organic matter (OM) of domanik rocks from high-carbon siliceous–carbonate–clay deposits of the Romashkino (Соrg 7.07%) and Taveli (Соrg 1.90%) fields and from low-carbon carbonate deposits of the Bavly field (Соrg 0.33%) in supercritical water (SCW) at 374°С and pressures of up to 24.6 MPa was determined. The rock samples differ in the mineral composition, OM (including kerogen) content, and composition of bituminoids being recovered. The effect of SCW on the degradation of the polymer structure of kerogen and high-molecular-mass bituminous components of domanik rocks of different lithological and facial types with the formation of petroleum fractions was demonstrated. The content of saturated HCs in extracts from high-carbon rocks of the Romashkino and Taveli fields increases after the treatment in SCW, whereas the content of aromatic compounds, resins, and asphaltenes decreases. The fraction of resins in the extract from the carbonate low-carbon rocks of the Bavly field, transformed under similar conditions, appreciably increases, whereas the content of saturated and aromatic HCs and of asphaltenes decreases. The extract from the rock of the Romashkino field, characterized by the highest content of OM and kerogen, contains, along with liquid fractions, also solid substances of carbene/carboid type. The content of n-alkanes and isoprenoids in the saturated fractions increases irrespective of the type of domanik rocks, whereas the content of polycyclic steranes, triterpanes, arylisoprenoids, and monoaromatic steroids decreases. A common trend is observed for aromatic fractions: the content of dibenzothiophenes and phenanthrenes increases, whereas the content of arylisoprenoids, naphthalenes, and benzothiophenes decreases. The main differences in the composition of HC fractions generated from rocks of different types are manifested in the molecular-mass distribution of n-alkanes С10–С36. The role of SCW in the formation of HC (СH4, C2H4, C2H6, C3H8, n-C4H10, and n-C5H12) and inorganic (H2, O2, and CO2) gases was demonstrated. The yield and composition of the gases, as well as of С10–С36 HC fractions, depend on the mineral composition of the rocks, on the content and composition of OM in the rocks, and on the heat resistance of the OM in SCW medium. [ABSTRACT FROM AUTHOR]

Gas samples were collected from 25 m long horizontal boreholes drilled into the excavation field at 10° inclination to the longwall face in two mining areas, Pesje and Preloge, in the Velenje Coal Mine, Slovenia, from 2013 to 2018. The degassing mechanism of coalbed gas and its stable isotopic composition (δ13CCO2, δ13CCH4, and δ2HCH4) were investigated in boreholes in advance of eight working faces. The major coalbed gas constituents were CO2 and methane. Gas concentrations and isotope values revealed that the methane is biogenic in origin with δ13CCH4 values of −69.4 to −29.5 ‰, δ2HCH4 values of −301 to −222 ‰, and a fractionation factor (αCO2-CH4) of 0.998–1.073, suggesting that methane derives from microbial acetate fermentation and CO2 reduction. The carbon dioxide methane index values ranged from 50.0–98.3 vol.% and δ13CCO2 values from −11.8 to −0.5 ‰, indicating that CO2 is biogenic and endogenic in origin. The degassing mechanism results in isotope fractionation of methane and CO2 for carbon isotopes up to 39.9 ‰ and up to 8.5 ‰, respectively, depending on the position of the excavation fields in space, e.g. under pre-mined coal area, fresh overburden. [ABSTRACT FROM AUTHOR]

Plasma technology finds applications in many industrial areas. To improve the process efficiency, different plasma forming gases and their mixtures are used. Since CO2 is economical and has high thermal conductivity, it is identified as a potential candidate in plasma material processing. However, the characteristics and merits of CO2 plasma arc in material processing are scanty. In this work, a 2D model is built to simulate plasma arc with CO2 and its mixtures with Ar. Effects of arc current, gas composition and arc length on the arc heating efficiency and arc characteristics are discussed. The arc size is strongly influenced by the gas composition at 200 A than at 100 A. Temperature distribution in the arcs is wider when CO2 content is decreased. The effect of arc current on the arc heating efficiency is stronger at lower current. Results predicted by the present model are compared with measured data for model validation. [ABSTRACT FROM AUTHOR]