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In-situ aeration of landfills accelerates biodegradation of waste organic matter and hence advances waste stabilization. The spatial outreach of aeration greatly affects stabilization efficiency. This study analyzed the spatial variability of gas composition and flow in 230 wells spread over four compartments of a Dutch landfill which is under in situ aeration since 2017, as well as the carbon extraction efficiency, tem-perature, and settlement. Flow rates and gas composition in the extraction wells varied strongly. The highest variability was observed in the compartment with the highest water tables with submerged filter screens for most wells, with low flow rates, and elevated ratios of CH4 to CO2, indicating predominance of anaerobic processes (compartment 11Z). The compartment with the most uniform distribution of gas flow rates, composition and lower ratios of CH4 to CO2, suggesting a significant share of aerobic carbon mineralization, also showed higher temperatures, a carbon extraction efficiency, and larger cumulative settlement, all indicative of enhanced microbial activity (compartment 11N). In this compartment, the amount of extracted carbon exceeded the carbon generation predicted from landfill gas modeling by the factor of 2 over the hitherto four years aeration. The effect of water tables on gas flow and the correlation between the flow, and the ratio of CH4 to CO2 appeared weak, indicating that also other factors than water tables influence gas concentration and flow. Future work includes stable isotope probing to analyze the significance of microbial respiration and microbial CH4 oxidation for the composition of the final extracted gas mixture.

The aim of this study was to preserve the quality and prevent the colour, lipid and protein oxidation in chicken breast fillet (pectoralis major muscle) during storage. For this purpose, modified atmospheres (MA) with four different gas mixtures (vol. %) of oxygen (O2 ), carbon dioxide (CO2 ) and nitrogen (N2 ) were used: oxygen free (0: 20: 80), low (20: 20: 60), medium (40: 20: 40), and high oxygen MA (70: 20: 10). After 9 days of storage in a refrigerator at 2 ± 1 °C, pH was measured, colour was evaluated instrumentally and sensorially, the basic chemical composition, thiobarbituric acid reactive substances (TBARs), and protein carbonyl content of raw chicken breast were determined. After thermal treatment (82 °C, 1 hour, sous-vide) of the breast fillet, the sensory characteristics of odour and aroma were evaluated, and the texture (Warner-Bratzler shear force) was measured instrumentally. The composition of the gas mixture affected all oxidation dependent parameters: (i) colour: L* and b* values were the highest under all MA with oxygen, and the a* value under MA without, medium and high-oxygen, (ii) lipids: the TBARs increased significantly under high oxygen MA after 7 days of storage (below the sensory thresholds value for rancidity), (iii) proteins: protein carbonyl content was the highest under medium and high oxygen MA, and (iv) sensory properties: colour oxidation and intensity of odd aromas under all MA with oxygen, as well as odour and aroma of stale in oxygen-free MA were increased. For chicken breast the most suitable is packaging under modified atmosphere without O2 , because the oxidation rate of colour, lipids and proteins during storage was the lowest., Cilj ovog istraživanja bio je sačuvati kvalitetu i spriječiti oksidaciju boje, lipida i proteina u filetima pilećih prsa (mišić pectoralis major) tijekom skladištenja. U tu svrhu korištene su modificirane atmosfere (MA) s četiri različite mješavine plinova (vol. %) i to kisika (O2 ), ugljikovog dioksida (CO2 ) i dušika (N2 ). MA su bile: bez kisika (0: 20: 80), s niskim sadržajem kisika (20: 20: 60), sa srednjim sadržajem kisika (40: 20: 40) i atmosfera s visokim sadržajem kisika (70: 20: 10). Nakon 9 dana skladištenja u hladnjači pri 2 ± 1 °C izmjeren je pH, boja je ocijenjena instrumentalno i senzorski te su utvrđeni osnovni kemijski sastav, reaktivne tvari tiobarbiturne kiseline (TBAR) i proteinsko-karbonilni sadržaj sirovih pilećih prsa. Nakon termičkog tretmana (82 °C, 1 sat, sous-vide) pilećeg fileta ocijenjene su senzorne karakteristike mirisa i arome, a tekstura je izmjerena instrumentalno (Warner-Bratzler rezivim sječivom). Sastav smjese plinova utjecao je na sve parametre zavisne o oksidaciji: (i) boja: L* and b* vrijednosti bile su najviše pod svim MA s kisikom, s a* vrijednost pod MA bez kisika, sa srednjim i visokim sadržajem kisika, (ii) lipidi: TBAR su se znatno povećale pod MA s visokim sadržajem kisika nakon 7 dana skladištenja (ispod senzornih graničnih vrijednosti užeglosti), (iii) proteini: proteinsko-karbonilni sadržaj bio je najviši pod MA sa srednjim i visokim sadržajem kisika, i (iv) senzorne karakteristike: povećana je oksidacija boje i intenzitet neobičnih aroma pod svima MA s kisikom, kao i miris i aroma ustajalog pod MA bez kisika. Za pileća prsa najprikladnije je pakiranje s modificiranom atmosferom bez kisika jer je brzina oksidacije boje, lipida i proteina tijekom skladištenja bila najniža., Ziel dieser Studie war es, die Qualität zu erhalten und die Oxidation von Farbe, Lipiden und Proteinen in Hähnchenbrustfilet (Musculus pectoralis major) während der Lagerung zu verhindern. Zu diesem Zweck wurden modifizierte Atmosphären (MA) mit vier verschiedenen Gasmischungen (Vol.-%) aus Sauerstoff (O2 ), Kohlendioxid (CO2 ) und Stickstoff (N2 ) verwendet: sauerstofffrei (0: 20: 80), niedrig (20: 20: 60), mittel (40: 20: 40) und hoch sauerstoffhaltig (70: 20: 10). Nach einer 9-tägigen Lagerung im Kühlschrank bei 2 ± 1 °C wurden der pH-Wert gemessen, die Farbe instrumentell und sensorisch bewertet sowie die chemische Grundzusammensetzung, die reaktiven Substanzen der Thiobarbitursäure (TBAR) und der Proteincarbonylgehalt der rohen Hühnerbrust bestimmt. Nach der thermischen Behandlung (82 °C, 1 Stunde, sous-vide) des Brustfilets wurden die sensorischen Merkmale Geruch und Aroma bewertet und die Textur (Warner-Bratzler-Scherklinge) instrumentell gemessen. Die Zusammensetzung des Gasgemisches beeinflusste alle oxidationsabhängigen Parameter: (i) Farbe: L*- und b*-Werte waren bei allen MA mit Sauerstoff am höchsten und der a*-Wert bei MA ohne Sauerstoffgehalt, bei mittlerem und hohem Sauerstoffgehalt, (ii) Lipide: die TBARs stiegen bei MA mit hohem Sauerstoffgehalt nach 7 Tagen Lagerung signifikant an (unterhalb des sensorischen Schwellenwerts für Ranzigkeit), (iii) Proteine: der Proteincarbonylgehalt war bei MA mit mittlerem und hohem Sauerstoffgehalt am höchsten und (iv) sensorische Eigenschaften: die Oxidation der Farbe und die Intensität der ungeraden Aromen bei allen MA mit Sauerstoff sowie der Geruch und das Aroma von abgestandenem Fleisch bei sauerstofffreier MA waren erhöht. Für Hähnchenbrust ist die Verpackung unter modifizierter Atmosphäre ohne O2 am besten geeignet, da die Oxidationsrate von Farbe, Lipiden und Proteinen während der Lagerung am geringsten war., El fin de este estudio fue preservar la calidad y prevenir la oxidación del color, de los lípidos y proteínas en los filetes de la pechuga de pollo (el músculo pectoralis mayor) durante el almacenamiento. Para ello fueron utilizadas las atmósferas modificadas (AM) con cuatro mezclas diferentes de gases (vol %), a saber, el oxígeno (O2 ), el dióxido de carbono (CO2 ) y el nitrógeno (N2 ). Las AM fueron: la atmósfera libre de oxígeno (0: 20: 80), la AM baja en oxígeno (20: 20: 60), la AM media en oxígeno (40: 20: 40) y la AM alta en oxígeno (70: 20: 10). Después de 9 días de almacenamiento en frío a 2 ± 1 °C, fue medido el pH, evaluado el color de forma instrumental y sensorial y fueron determinados la composición química básica, las sustancias reactivas al ácido tiobarbitúrico (TBAR) y el contenido de proteína-carbonilo de la pechuga de pollo cruda. Luego del tratamiento térmico (82 °C, 1 hora, sous-vide) del filete de pollo, fueron evaluadas las características sensoriales de olor y aroma, y fue medida la textura de manera instrumental (corte tipo Warner-Bratzler). La composición de la mezcla de gases afectó todos los parámetros dependientes de la oxidación: (i) color: los valores L* y b* fueron los más altos en todos los AM con oxígeno, con un valor a* en AM sin oxígeno, con contenido de oxígeno medio y alto, (ii) lípidos: los TBAR aumentaron significativamente bajo MA con alto contenido de oxígeno después de 7 días de almacenamiento (por debajo de los valores límite sensoriales), (iii) proteínas: el contenido de proteína-carbonilo fue más alto bajo AM con contenido de oxígeno medio y alto, y (iv) características sensoriales: mayor oxidación del color e intensidad de aromas inusuales bajo todos los AM con oxígeno, así como el olor y el aroma rancio bajo AM sin oxígeno. Para las pechugas de pollo, el envasado con una atmósfera libre de oxígeno modificado es más apropiado porque la tasa de oxidación del color, los lípidos y las proteínas durante el almacenamiento fue la más baja., Lo scopo di questo studio consisteva nel preservare la qualità e prevenire l'ossidazione del colore, dei lipidi e delle proteine nei filetti di petto di pollo (muscolo grande pettorale) durante la conservazione. A tale scopo sono state utilizzate atmosfere modificate (MA) con quattro diverse miscele di gas (vol. %) a base di ossigeno (O2 ), anidride carbonica (CO2 ) e azoto (N2 ). Sono state utilizzate le seguenti MA: senza ossigeno (0: 20: 80), a bassa (20: 20: 60), media (40: 20: 40) e alta concentrazione di ossigeno (70: 20: 10). Dopo 9 giorni di conservazione in frigorifero a 2 ± 1 °C, è stato misurato il pH, il colore è stato valutato strumentalmente e sensorialmente, sono state determinate la composizione chimica di base, le sostanze reattive all'acido tiobarbiturico (TBAR) e il contenuto di carbonile proteico del petto di pollo crudo. Dopo il trattamento termico (82 °C, 1 ora, sottovuoto) dei filetti di petto di pollo, sono state valutate le caratteristiche sensoriali di odore e aroma, mentre la consistenza è stata misurata strumentalmente (con dispositivo Warner-Bratzler). La composizione della miscela di gas ha influenzato tutti i parametri dipendenti dall'ossidazione: (i) colore: i valori L* e b* erano i più alti in tutti gli MA con ossigeno e il valore a* in MA senza O2 e con ossigeno medio e alto, (ii) lipidi: i TBAR sono aumentati significativamente con MA ad alto contenuto di ossigeno dopo 7 giorni di conservazione (al di sotto del valore delle soglie sensoriali per l'irrancidimento), (iii) proteine: il contenuto di carbonile proteico è risultato il più alto con MA con ossigeno medio e alto e (iv) le proprietà sensoriali: l'ossidazione del colore e l'intensità degli aromi insoliti sono aumentate in tutte le MA con ossigeno, così come l'odore e l'aroma di stantio nelle MA senza ossigeno. Per il petto di pollo, il confezionamento più indicato sembra essere quello in atmosfera modificata senza ossigeno, perché il tasso di ossidazione del colore, dei lipidi e delle proteine durante la conservazione è risultato il più basso.

Blending hydrogen into the natural gas (NG) network could provide an efficient pathway for decarbonising the NG system through power-to-gas technologies. However, due to the presence of potentially multiple and intermittent hydrogen injection sources, the gas blended throughout the network would be neither homogenous nor at a constant mole fraction. The above features are not captured by the current transient modelling techniques. To bridge this gap, this work presents a transient analysis model that enables the tracking of gas compositions and particularly hydrogen fractions in real-world meshed networks with multiple NG sources, non-pipe elements, and multiple and intermittent hydrogen injection sources. A time-varying compressibility factor is also introduced to account for the variable gas composition across the network. Moreover, numerical techniques are adopted for improving the stability of the Eulerian numerical calculation, and a specific grid size threshold Δxmax is introduced for selecting the stable mesh grid to alleviate convection-dominated oscillations caused by the hydrogen fraction tracking. The case study based on the well-known 20-node Belgian gas network validates the effectiveness of the method in solving practical-scale problems, whereas the unsuitability of steady-state models is also discussed and highlighted. The results clearly demonstrate the effect and importance of introducing variable compressibility factor, hydrogen fraction tracking, and variable gas demand. The impacts of hydrogen blending on pressures and linepack of the network are further investigated.

Methanation of CO2 using H2 obtained by renewable energy sources has been gaining attention as one of the promising options for utilizing captured CO2 and surplus power obtained when intermittent p...

Controlled ice nucleation offers several key benefits to the pharmaceutical lyophilization process, including reducing lyophilization cycle time, control of ice crystal morphology, and increased consistency of lyophilized product quality attributes. The rapid depressurization based controlled ice nucleation technique is one of the several demonstrated controlled ice nucleation technologies and relies on the rapid discharge of an inert pressurized gas to induce ice nucleation. In this work, a series of custom wireless gas pressure and temperature sensors were developed and applied to this process to better understand the mechanism of controlled ice nucleation by depressurization. The devices capture highly transient conditions both in the chamber near the vial and within the vial headspace throughout the entire process. The effects of ballast gas composition, initial charge pressure, and vial size on gas pressure and headspace/chamber temperature are explored individually. We model the depressurization as an isentropic process, allowing the influence of these parameters to be evaluated quantitatively. It is demonstrated that monatomic gases (e.g. argon) with low thermal conductivity produce the most favorable conditions for ice nucleation at the end of depressurization, based on temperature drop in the vial headspace. Experimental data also reveal a correlation between initial charge pressure and vial size with the temperature drop within the vial headspace, during depressurization. These findings ultimately provide deeper insight into the rapid depressurization based controlled ice nucleation process and help lay the foundation for a more robust process development and control.

In the present study, the countermeasures are proposed to minimize the problem on torque and power output performance and exhaust gas emissions of natural gas engine with use of lower calorific gas. An experiment was conducted to identify thermal efficiency and harmful exhaust gas emission characteristics under partial load conditions in order to improve efficient fuel use in engines affected by the introduction of low calorific gases. A countermeasure for coping with emission gas regulations and preventing thermal efficiency deterioration under rated power operating conditions was then presented. An 11 L six-cylinder turbo-charged engine for city buses compliant with the EURO 6 regulation was used in the experiment, and the results obtained using the reference natural gas fuel were compared with those obtained using simulated low calorific gases. Pure methane (CH 4) was also used to investigate the effects of gas composition changes on thermal efficiency and exhaust gas emissions. When N 2 is added or pure CH 4 is used under partial load operating conditions, the combustion rate decreases; consequently, the optimum ignition timing is additionally advanced relative to that obtained when the reference natural gas fuel is used. If the N 2 mixing ratio is increased to a minimum of 4.7% under rated power operating conditions, combustion becomes unstable. Stable operation can be secured by increasing the set base fuel amount, 2.35% and 9.41% for pure CH 4 and 8% N 2 , respectively; however, torque decreases in proportion to the combustion speed of the gas fuel. The strategy of boost pressure control for the torque compensation can minimize the decrease in thermal efficiency.

Hydrogen is being considered integral to the future energy landscape but there is limited mechanistic understanding and a lack of predictive models to describe the combined effects of alloy and gas composition, temperature, thermal cycling and water vapor contents on the oxidation behavior of high-temperature materials. Experimental evaluations were combined with coupled thermodynamic-kinetic modeling to investigate the oxidation behavior of five representative Ni-based superalloys in two water vapor contents (10%, 60% H2O) under thermal cycling (1-h, 100-h cyles) conditions at 800°C and 1000°C. The alloy with the highest Ti content demonstrated the poorest cyclic oxidation behavior while the alloy with highest Cr and Al contents was expected to continue to support protective formation of a compact Al2O3 scale. Accelerated degradation of the chromia-forming alloys was observed in the higher water vapor content but the impact on transient oxidation of the alumina-forming alloys needs further investigations.

Gasification is a multiphase process that converts the solid fuels into useful synthetic gas. Despite the potential of biomass gasification as a clean technique to produce a high caloric value syngas, it is not as well looked upon as its advantages suggest. In the present study, an ASPEN plus model of biomass gasification was developed with considering the kinetics of the reactions and tar cracking mechanism. Firstly, the model was validated against the experimental data in the literature. Next, a parametric study was done to investigate and evaluate the performance and produced gas composition of air–steam gasification of biomass. The effect of various operational parameters, such as the reaction temperature, equivalence ratio (ER) and steam/biomass ratio (S/B) on the gas product composition, products yield and the gasifier performance was investigated. The results showed that the increase of reaction temperature not only can enhance the H2 content in the gas stream, but inhibit the formation of tar. The achieved optimal conditions for production of maximum H2 content (16.18 vol %) were as follows: reaction temperature of 800 °C, S/B of 0.8 and ER of 0.211.

During the first tentative examination of Matsesta's personnel working in conditions of toxic concentration of hydrogen sulfide, we felt an urgent need to conduct parallel experiments on animals.

In the dry etching of borosilicate glass (BSG), the process gas reacts with the impurities of borosilicate glass and forms a non-volatile compound layer on the surface. This surface compound layer (SCL) makes it difficult to control the surface morphology and device structure dimension with precision and significantly influences the etch rate. We examined the influence of SCL on the etch rate of quartz and BSG and discussed its etching mechanism depending on the thickness of the SCL. The formation of SCL was dominated by both the plasma gas composition and substrate material, and the etching regime can be defined by the thickness of the SCL. A thin SCL was formed on the BSG by CF4/Ar gas plasma etching, and the etch rate was suppressed by the SCL. A significantly thin SCL was formed on the quartz specimens under in same etching conditions, and a direct etching reaction was occurred. As the ratio of physical etching gas (Ar) increased, both the ion energy flux and the physical ion bombardment increased and consequently improved the etch rate. The SCL plays the role of an F radical supplier, while the thick SCL reduces the etch rate because it takes time for the etchants to transit from the surface to the interface. The SCL acts as a barrier in the etching reaction, which could be adjusted by the regulation of the etching gas composition or the plasma parameters, such as the inductive power and the bias power of the RIE reactor. [2021-0071]

The paper presents the study focused on the application of poultry manure as an energy resource. Such solution is expected to bring limitation of fossil fuels exploitation, reduction of poultry farming costs, as well as sustainable waste to energy conversion. The study was performed by the use of a prototype gasification installation. The study involved analysis of the outlet gas composition, calorific value and flue gas emission. Measured heat of combustion of dry poultry manure is comparable to wood or straw. It contains relatively large amount of ash (9.11%), volatile components (78.4%) and low amount of sulphur. The chemical composition of obtained ash, shows low contribution of components elevating the melting temperature and high contribution of components decreasing the melting temperature, which indicates slagging tendency. The calorific value of the process gas, ranges from 6.47 MJ/m3 to 9.47 MJ/m3. Measured emission values match the applicable standards, except dust content. Performed studies indicated that poultry manure is a valuable energy resource, which allows to reduce the use of fossil fuels for the needs of poultry farming. Obtained results are essential for the design and operation of gasification installation in order to avoid operation problems associated with slagging of the gasification chamber.

The paper presents the thermodynamic modeling results of zinc and iron reduction from B2O3 ‒ CaO ‒ Fe2O3 ‒ ZnО melts by CO ‒ CO2 and H2 ‒ H2O mixtures containing 0 – 60 % CO2 (H2O) at 1273 – 1673 K using a technique describing the reduction of metals from an oxide melt by gas in bubbling processes, under conditions that provide an approximation to real systems. Its originality is equilibrium determination for each individual portion of gas supplied into the working fluid. The reducible metals oxides content in each calculation cycle is taken from the previous data. During the calculations, changes in the content of zinc (СZnO ) and iron (СFe2O3 , СFe3O4 and СFeO ) oxides in the melt and the degree of their reduction were estimated. When using CO or H2 as a reducing agent, this process proceeds in three stages. In the first stage, Fe2O3 is reduced to Fe3O4 and FeO. CFe2O3 values decrease to almost zero, while CFe3O4 and CFeO increase simultaneously. By the end of the stage, СFe3O4 reaches its maximum value. At the second stage, the Fe3O4 → FeO transition occurs, when СFeO values reach its maximum. At these stages, there is a slight increase in the CZnO . At the third stage, the values CFeO and CZnO decrease, and iron and zinc are reduced. An increase in temperature dramatically reduces the gas consumption for zinc reduction by 2 – 3 times, and the replacement of CO with H2 reduces it by less than 20 %. In the presence of oxidizing agents (CO or H2O), only zinc is reduced. The process ends when the final content of zinc oxide in the melt corresponds to the equilibrium with the initial gas composition. The higher the temperature, the less CZnO is. The obtained data are useful for the development of technologies for the selective recovery of metals.

Diesel particulate matter (DPM) and oxides of nitrogen (NOx) are the emissions from diesel engines (compression ignition engines) of the most concern and are currently strictly regulated. In this work, we present an alternative diesel emission control technique to assist in further emission reduction. An experiment-oriented study on diesel engine emission abatement using low-power, low-frequency, high-voltage discharge (HVD) treatment was carried out in a laboratory-scale reactor with whole diesel engine exhaust gas. A dielectric barrier discharge (DBD) reactor was used in direct contact with diesel exhaust gas at atmospheric temperature with an input energy density between 200 and 400 J/L. An investigation of the direct effect of the high-voltage discharge reactor on the diesel exhaust gas treatment was carried out to characterize both diesel particle and gaseous emissions. The proposed HVD system demonstrated up to 95% particulate matter reduction by mass or 64% reduction by number, and 63% reduction of the diesel soot particle geometrical mean diameter by HVD-generated O3 oxidation. Thermogravimetric analysis revealed the significant change in the diesel soot compositions and oxidation characteristics. HVD-treated particulate matter demonstrated a lower reactivity in comparison to untreated soot. Gas composition analysis indicated the generation of free radicals (e, O, OH, O3, and N) by the HVD system, as mainly indicated by the increase of the NO2/NO ratio and concentration of CO and O2. The pattern of CO2 reduction while CO and O2 increased indicated the dissociation of CO2 by HVD. Free radicals generated by HVD directly affected DeNO, DeNOx, NO2/NO ratio, and CO and CO2 selectivities.

The top surface of carbon nanotube (CNT) “forests” produced by thermal chemical vapor deposition (CVD) often has a tangled morphology, owing to the self-organization of the CNTs at the initial stage of the CVD process. Removal of this top “crust” layer, without damaging the intrinsic microstructure of the CNT forest is often a key step for further applications. This paper studies the tailored use of Ar/O2 plasma etching to modify the surface morphology of multi-walled CNT forests. First, we investigate the effects of process parameters including plasma power, flow rate, and gas composition on the etching of CNT forests. As a result, we identify the plasma conditions that successfully remove the top crust yet maintain the structural shape of a CNT forest. Second, we prepare CNT forests having different packing densities and heights to study the influence of the initial characteristics on the etching result. We experimentally confirm that the etching rate depends strongly on the density and morphology of the crust layer. We also compare the material removal rate in vertical and lateral directions. Finally, we explore the enhancement of alignment and chemical uniformity of the top surface of CNT forests by the Ar/O2 plasma

In this paper, the plasma coupled catalyst was used for the dry reforming of methane (DRM). The impacts of the reaction temperature, the molar ratio of CO2/CH4, and the concentration of the main gas components (N2, H2, CO, H2O) on the conversion rate of CH4 and the energy efficiency of plasma catalysis were observed. The results shows that the conversion rate of CH4 is 41.57%, with La-Ni/γ-Al2O3 as the catalyst, the reaction temperature being 450°C and the molar ratio of CO2/CH4 being 1.0, and without other gases. The conversion rate of CH4 increases with the increase of the molar ratio of CO2/CH4. The conversion rate of CH4 is 92.82% respectively during DRM by plasma catalysis, with the molar ratio of CO2/CH4 being 5.0. The reaction temperature and the molar ratio of CO2/CH4 have a significant effect on CH4 conversion. The excited particles in the system are influenced by the changes of gas composition, which affect not only CH4 conversion directly, but also the carbon deposition on the surface of catalyst. The addition of N2 and H2O in the reaction system not only improves conversion of CH4 but also inhibits carbon deposition; the addition of H2 and CO reduces the conversion of CH4 significantly. The results are expected to provide basic data and reference for the development of the synthetic process of chemicals through biomass gasification.

Aim. To study the features of the gas composition and acid-base state in newborns with specific intrauterine infections.Material and methods. The examination was conducted based on the neonatal pathology unit of the SI NMCShifobakhsh.The degree of oxygenation of blood and skin was determined using daily pulse-oximetry. The partial pressure of gases and the study of the acid-base state (CBS) of blood was carried out using Convergys/liquid device.Result and discussion. The results of our study of blood gases and the acid-base indicator of blood in newborns with severe IUI showed noticeable hypoxemia, moderate hypercapnia, and a deficiency of buffer States, which indicate a violation of gas exchange function in the lungs with the development of compensatory respiratory-metabolic acidosis in children of this group. In patients with a very severe course of IUI, as the syndrome of respiratory disorders and the severity of hyperventilation syndrome increased, deeper changes in blood gas parameters and the acid-base state of the blood were noted. It indicates significant damage to the ventilation function of the lungs, diffuse perfusion processes, gas, and acid-base homeostasis.Conclusions. Impairment of the function of organs and systems that developed against the background of a severe or very severe course of IUI, depending on the degree of severity of deviations in blood gas parameters and acid-base balance, shows the need for adequate corrective therapy.

A novel high sensitivity all-fiber Fabry-Perot interferometer (FPI) gas refractive index (RI) sensor based on hole-assisted one-core fiber (HAOCF) and Vernier effect was proposed and demonstrated. The sensor is fabricated by splicing a section of HAOCF to a section of silica tube (ST) fused with the lead-in single-mode fiber (SMF), ensuring that the sensor is composed of an air-cavity FPI and a silica-cavity FPI. The cascaded dual-cavities generate the Vernier effect due to a similar free spectrum range (FSR), which significantly improve the sensitivity of the sensor. Owing to the air hole in the cladding of the HAOCF, gases with different RI can enter or leave the in-fiber air cavity, which makes the device usable as a gas RI sensor. The sensor was used to monitor the RI changes of air with different pressures and provided a high sensitivity of −9462.4 nm/RIU. The proposed sensor has a potential to find further applications in the fields of gas composition detection, medical diagnostics and environmental monitoring.

In this work, the transition boundary of high-temperature co-electrolysis towards pure CO2-electrolysis was investigated. AC and DC measurements with H2O concentrations from 0.0%eq to 39.7%eq led to the identification of the underlying electrochemical processes. Comparison of CO2 conversion in the (R)WGS reaction with electrochemical CO2 reduction by means of area specific resistance (ASR) showed that gas composition determines the dominant reduction reaction (H2O or CO2 reduction). The cell performance of CO2-electrolysis was found to be comparable to co-electrolysis in the boundary region up to around 4.7 %eq H2O. The threshold for the perception of CO2-electrolysis during co-electrolysis has been established to be around 31.7 %eq H2O. The hypothesis that pre-domination of CO2-electrolysis increases with decreasing H2O concentrations below this boundary limit was underlined by measurement results.

Bio-oil derived from fast pyrolysis of oil palm empty fruit bunch (EFB) was catalytically reformed inside a stainless steel multichannel tubular reactor using steam and air as reforming agents. The catalyst used, denoted as Fe/AC, was an iron catalyst loaded on the coconut shell-derived activated carbon (AC) prepared by a new approach of impregnating iron from an aqueous solution onto the AC in a stepwise manner. Results indicate that a stepwise impregnation was able to minimise the agglomeration of iron particles on AC surface, allowing high loading of iron onto the AC without severely affecting Fe dispersion and catalyst pore properties. The highly reducible, highly efficient catalyst produced in this study was able to lower the concentration of tar in producer gas to lower than 100 mg/Nm3. The best composition of the burnable product gas was obtained with iron loading of 15 wt%, reaction temperature of 800 °C, steam-to-carbon molar ratio (S/C) of 1.0 and air equivalence ratio (ER) of 0.1, with gas composition of 33.5% H2, 21.0% CO, 14.0% CH4, 18.8% CO2 and 1% C2 hydrocarbons and a cold gas efficiency of 78.5%.

Oxidation of the Fe-base alloy T22 in humid air at 500 °C was investigated. The samples were exposed for up to 1000 h at 1 bar and 20 bar. The influence of three furnace tube materials, alumina, ET45 and quartz glass, on the oxide scale morphology was investigated. Samples and their cross sections were examined using optical microscopy, scanning electron microscopy, electron probe micro analysis and Raman spectroscopy. Multilayered oxide scales consisting of hematite, magnetite and Fe–Cr spinel were found on all samples. However, the composition and morphology of the oxide scales depend on the furnace tube material and on the system pressure. The system pressure is assumed to change the reaction equilibria and adsorption rates. The tube material changed the initial gas composition by formation of volatile Cr species. This volatilization rate increased at higher system pressures.

In this study, the adsorption–desorption/induced strains/permeability characteristics of seven columnar coal samples with Ro.ran ranging from 0.42 to 3.23% were monitored dynamically during N2-enhanced coalbed methane (N2–ECBM) recovery. The results showed that N2 injection and sealing (N2–IS) is an important step in N2–ECBM recovery, with average desorption of 60.25%. During desorption with stepwise depressurization (DSD), the desorption volume increased linearly with time. The breakthrough point of gas production was in the first gas drainage phase, and the low-rank coal reservoirs entered the depletion well stage earlier. The samples were subjected to N2–IS and DSD, the cumulative desorption of the samples was in the 88.03–100.96% range, and the average desorption of the medium-rank coals was 100.40%. The residual volume strain was negative in medium-rank coals and caused by pore–fracture structural damage. The induced strain behavior was independent of gas composition, but with the gas volume being polynomial, it had a predictive effect. The permeability recovery percentage (PRP) during N2–IS was in the order of medium- > high- > low-rank coal, and the PRP of medium-rank coal was up to 90%. The strain sensitivity coefficient of low-rank coal increased with increase in volume strain, that of medium-rank was independent of volume strain, and that of high-rank coal decreased with increase in volume strain. This work revealed that, by injecting N2 into the reservoir and sealing the well for a certain period of time while maintaining high reservoir pressure, CH4 desorption induced coal volume shrinkage, the fracture aperture was restored, and some new fractures were induced, increasing permeability; in addition, DSD can be more consistent with the gas production process.

The microscopic mechanism of the competitive adsorption of CH4, CO2 and N2 in coal is the theoretical basis for enhancing coal seam gas recovery by injecting CO2 (CO2-ECBM). Based on this principle, this work used Grand Canonical Monte Carlo and Molecular Dynamics to investigate the microscopic adsorption mechanism of single, binary, and ternary component gases in Wiser bituminous coal molecules. The adsorption mechanism was explored by changing gas composition and concentration. The comparison of adsorption separation coefficients suggested that CO2 had the highest adsorption capacity, whereas N2 had the lowest capacity. When the CO2 concentration in the gas mixture was high, the adsorption amount was large and the adsorption separation coefficient was small. This finding indicated that high concentrations of CO2 had negative effects on competitive adsorption. Energy changes were also evaluated. The potential energy between CO2 and the framework was the strongest among the two other gases. The inhibition of CH4 adsorption intensified with decreasing molar fraction of CO2. This phenomenon was explained from the perspective of heat of adsorption. As the molar fraction of CO2 in the adsorption system decreased, the heat of the isotherm adsorption increased. Meanwhile, the adsorption system became unstable and the capacity of CH4 adsorption on the framework weakened. Results provide a theoretical basis for the use of CO2-ECBM.

Separation of mixtures, gases, and phases is of great industrial importance. Various methods and equipment are utilized for the separation. One of the most novel and innovative as well as efficient methods is supersonic separation where acceleration of the flow mixture is accompanied by fast reduction in temperature and pressure. As a consequence, heavier components which have a higher condensation temperature will liquefy faster than lighter components. Swirling flow and centrifugal force will drive heavier condensed droplets toward the outer wall and separate them from lighter components in the gas phase. In general, supersonic separators consist of a converging-diverging nozzle and a cyclone separator. Due to no moving or rotating parts, supersonic separators have high reliability, long endurance, easy manufacturing, and less expensive operation and maintenance. In this paper, the one-dimensional design of a supersonic separator for separation and purifying of Methane from natural gas mixture is presented. Since separation process is in vicinity of saturation line, real gas model from NIST REFPROP software is used to estimate the fluid thermodynamic properties. For the design of cyclone separator and phase separations, instantaneous nucleation at the nozzle discharge is assumed and displacement of smallest droplet (as the worst case) is only considered. After calculating the supersonic separator geometry, performance sensitivity to changes in inlet temperature, pressure, and gas composition is studied, the effectiveness of these parameters is compared and rate of performance change is calculated. At next step, the simultaneous change of the inlet conditions is investigated and effect of each parameter on the effectiveness of others is studied. Finally, in order to optimize phase separation in various operating conditions, effects of swirler angle and swirl intensity on separation length are studied and optimum swirl intensity to gain the best possible separation performance with a fixed geometry separator for different inlet conditions is determined.

The application of membrane separation processes to industrial hydrogen-rich waste gases promotes the efficient recovery of this clean fuel. The first step to address and overcome this waste of resources is to assess the real performance of commercially available polymeric membranes for hydrogen separation in terms of hydrogen purity that meets the quality standards to be used in hydrogen-based applications. Therefore, this work makes a comparison of the performance of commercial flat hydrogen-selective membranes based on non-porous polymeric materials through the experimental assessment in a lab-scale set up that contains a gas permeation cell with the aim of recovering hydrogen from the most suitable multicomponent waste gaseous streams. To assess the mixed-gas permeation performance, the influence of the feed gas composition, temperature and pressure was examined. The results of experimental tests indicated that there is a strong dependency of H2 permeability on CO2 concentration, that induces a decay of H2/CO2 selectivity in mixed-gas experiments for the membranes under study. Accordingly, the permeability-selectivity trade-off in the state-of-the-art membranes defines the balance between H2 recovery and the product purity. Finally, it is worth noting that although H2 purities obtained are higher than 98% vol. H2 for APG and COG mixtures, which may indeed be used as a commodity chemical in many industrial processes, they are still far from fuel cell requirements. This research was supported by the projects CTQ2016-75158-R (AEI/FEDER, UE), RTI2018-093310-B-I00 (MINECO/AEI/FEDER, UE), and PEMFC-SUDOE project (SOE1/P1/E0293 - INTERREG SUDOE/FEDER, UE), “Energy Sustainability at the SUDOE Region: Red PEMFC-SUDOE”.

Adaptation of a mathematical model of gas diffusion combustion for different flow rates of CO–H2 and a constant coal flow rate is carried out. It is shown that the results of calculating the main characteristics of the flame are in satisfactory agreement with experimental data and can be used to determine the structure of pulverized coal–gas flow, gas composition, particle and gas temperature, carbon combustion efficiency, etc. The proposed model is suitable for analyzing the stability of coal–gas flame and the transient processes accompanying changes in the mode of supply of the fuel-oxidizer medium.

Chemical vapor deposition is an important method for the preparation of boron carbide. Knowledge of the correlation between the phase composition of the deposit and the deposition conditions (temperature, inlet gas composition, total pressure, reactor configuration, and total flow rate) has not been completely determined. In this work, a novel approach to identify the kinetic mechanisms for the deposit composition is presented. Machine leaning (ML) and computational fluid dynamic (CFD) techniques are utilized to identify core factors that influence the deposit composition. It has been shown that ML, combined with CFD, can reduce the prediction error from 25% to 7%, compared with the ML approach alone. The sensitivity coefficient study shows that BHCl2 and BCl3 produce the most boron atoms, while C2H4 and CH4 are the main sources of carbon atoms. The new approach can accurately predict the deposited boron-carbon ratio and provide a new design solution for other multi-element systems.

The gas produced by gasification is more versatile than the original solid biomass and can be applied as raw material for chemical industry and as fuel for the electrical and thermal energy production. Small gasification plants are being considered as an option for electrical energy generation in remote areas where agriculture wastes can be found easily. In this way, the aim of this work was to evaluate the characteristics of the gas composition of co-gasification using pine pellets and blends with agricultural wastes. The experiments were carried out in duplicate in a pilot scale fixed bed downdraft gasifier, GEK Power Pallet 20kW. It was performed experimental runs with 100 % pine pellets, 80 % pine pellets and 20 % agriculture wastes, and 80 % pine pellets with 15.4 % agriculture wastes and 4.6 % of glycerol used as an agglutinant agent. The samples were analyzed by GC-FID/TCD. The moisture of different feedstocks varied between 8.00 and 10.88. The results of the produced gas show an average composition of 37.45% CO and 15.79% H2, and LHV 7,155 kJ/kg for gasification of 100 % pine pellets. While the mixture of pine pellets and agriculture wastes resulted in a gas with 32.13% CO and 20.10% H2, and LHV of 6,663.4 kJ/kg. When added glycerol, the gas composition to CO was 20.52 % and to H2 11.21 % with LHV of 4,507.4 kJ/kg. The results indicate that the gasifier is compatible with the mixture of agricultural residues and pines pellets in co-gasification.

Biomass gasification generates a gas mixture (syngas) that constitutes a rich source of carbon and energy for the production of second-generation renewable fuels such as biomethane. However, the produced syngas composition (H2/CO/CO2) cannot be converted to natural gas grade biomethane due to stoichiometric limitations, and a waste stream of CO2 is released unexploited in the atmosphere. The present study introduces the concept of biomass gasification coupled to syngas biomethanation with in-situ exogenous H2 supply for the complete sequestration of the syngas carbon, the valorization of renewable excess electricity from wind and solar power and the production of biomethane satisfying the criteria for injection in the natural gas grid. Syngas biomethanation was executed by mixed microbial consortia in a trickle bed reactor at 37 °C and 60 °C. The assessment of the effects of the net inlet gas composition was performed according to a hereby proposed syngas quality index (SQI), which is based on the syngas content in compounds able to act as carbon and electron donors and the stoichiometry of methane production. The SQI of the stoichiometrically ideal syngas composition is 4. Values below 4 correspond to a stoichiometric carbon-moles excess while values above 4 correspond to a stoichiometric electron-moles excess. It was demonstrated that switching the SQI of the supplied syngas from 1.44 to 3.67 increased the CH4 content in the outlet of the reactor from 30 to 72%, accompanied by an at least 1.2-fold increase of the CH4 productivity. A SQI of 4.78 (> 4) resulted in a significant deterioration of the quality of the produced biomethane due to a high content (52–54%) of unconverted H2 and because of thermodynamic limitations on carboxydotrophic hydrogenogenesis in thermophilic conditions. Maximal carbon sequestration and production of natural gas grade biomethane was shown to be feasible at a SQI = 3.98 in thermophilic conditions. Graphic Abstract: [Figure not available: see fulltext.]

Modified atmosphere packaging (MAP) is widely used for the preservation of fresh-cut fruit and vegetables. But many commercial polymeric films are limited to MAP applicability due to a low gas permeability of these films. Laser perforation is a novel method to provide micropores that raises gas permeability. Laser-induced micropore-based MAP (0, 2, 4, 6, 8 pores) and carbon-dot/chitosan (CDs/CH) coating with CD concentration of 4.5% for the preservation of fresh-cut cucumber during storage were investigated. Fresh-cut cucumber was coated by chitosan carbon-dot, packaged by micropore-based packaging bag of about 100 μm, then stored at 4 °C for 15 days. Results showed that micropore-based MAP (100 μm) can effectively adjust the gas composition of fresh-cut cucumber during storage. Micropore-based MAP (100 μm) with four micropores in combination with CD/CH coating provided appropriate O2 concentration of 9.8% and CO2 concentration of 10.3%. Micropore-based MAP (100 μm) with four micropores and CDs/CH coating effectively maintained minimum weight loss of 4.1%, firmness of 6.6 N, and aerobic plate count of 5.02 log CFU g−1, malondialdehyde content of 2.94μmol kg−1, and inhibited the degradation of flavor as well as the maintenance in water distribution behavior at the 15th day of storage. Therefore, micropore-based MAP in combination with chitosan carbon-dot coating can be used as an effective method for the preservation of fresh-cut cucumber.

Underground coal mining operations produce large numbers of gobs that contain methane from mining coal seams and their adjacent coal seams. In longwall mining, gob methane is released to coal faces, presenting safety issues. Therefore, if gob methane sources can by identified accurately under extraction conditions, then efficient methane extraction strategies can be adopted to maximize the capture of methane from gobs and to control effectively methane flow to the coal face, thereby reducing safety risks. In this study, a new method to determine quantitatively gob methane sources under extraction conditions was proposed and tested in China’s Liyazhuang Coal Mine. Firstly, the isotope and gas composition of methane desorbed from coal cores of the mining seams and their adjacent seams, as well as methane collected from methane drainage boreholes at different heights in the gobs, were measured. Then, an isotope source model for calculating gob methane sources was established. Finally, based on isotope and gas compositions, the proportions of sources of gob methane that had been extracted from methane drainage boreholes were determined using the afore-mentioned model, and the extraction range that could maximize efficiently the control of methane emissions from each methane source was obtained.

The variation in the heat fluxes from the arcs with the wall height in 100-ton electric arc furnaces (EAF) for different arc lengths and slag layer thicknesses and constant arc power are calculated and analyzed. As the depth of submersion of the arcs into the slag is increased from 70 to 300 mm, the maximum heat flux in the lower part of walls decreases by half. As the arc length is decreased by a factor of 1.5 while the arc power remains constant, the heat flux decreases by 10 to 30% and its distribution over the height and perimeter of the walls changes.

Since 2011, the Devonian Berea Sandstone in northeastern Kentucky has produced oil where thermal maturity studies indicate that likely source rocks, namely, the Devonian Ohio Shale and Mississippian Sunbury Shale, are thermally immature. Downdip, where source rocks are mature for oil, the Berea Sandstone and Ohio Shale primarily produce gas. To investigate this thermal maturity discordancy, the molecular and isotopic composition of gases from the Berea Sandstone (oil associated) and Ohio Shale (nonassociated) were analyzed to understand the gas generation and migration history. Collected along a northwest-southeast transect in eastern Kentucky, samples range from 1079 to 4602 ft, respectively. All are wet gases with a thermogenic origin (δ13C-CH4 e −53.5‰ to −46.1‰). This is mostly consistent with a reevaluation of thermal maturity in a companion study that expands the area mature for oil. Gas migration is required, however, in updip parts of the Berea play where vitrinite reflectance (VRo) values are less than 0.6%. Southeast regional dip exerts a first-order influence on thermal maturity as gases become drier and isotopically heavier downdip. Correlation of δ13C values for heavier hydrocarbon gases in a natural gas plot with VRo contour spacing demonstrates the influence of nearby source rock thermal maturity on gas composition. Downdip, migration of oil and the attendant increase in permeability relative to gas may account for the dominance of gas production in the Ohio Shale. Migration along with basin uplift after the Alleghany orogeny may have contributed to development of a gas phase that exsolved from oil.

This paper shows the results of a study of gas evolution from a patented modified cellulose mix used in the production of no-bake casting moulds. The modified cellulose mixture was used for investigation with additives such as expanded perlite, expanded vermiculite and microspheres. The binder was an inorganic resin based on commercial technology, called Geopol. Samples were tested in different compositions in order to show the influence of all the additives mentioned. Two different methods were used—one was based on TG–TDG–MS investigation and the other was based on pyrolysis combined with a gas composition analyser. Investigations of both methods were carried out at temperatures up to 900 °C. The results showed that the gas emissions during thermal degradation of all the modified mixtures did not constitute substances that are hazardous or dangerous to health. Therefore, the material proposed can be used as a solution that is more environmentally friendly when compared to formulas which exist on the market and are abundant in harmful compounds.

In this study, a one-dimensional generic model capable of being integrated with reactor scale models is proposed for a single pellet through solving the transient differential conservation equations. Predicted results comparison with the experimental data showed close agreement. In addition, the model was used to investigate the relevance of physical characteristics of pellet, reacting gas composition, diffusion factors, and prevailing regime. It was found that the pure magnetite pellet could achieve a temperature rise of about 245 K at oxygen concentration of 40 vol.%, whereas the maximum temperature difference inside the pellet was approximately 24 K. Moreover, increasing pellet size, the maximum attainable temperature reached a peak and then leveled out. Furthermore, by decreasing the pore diameter, the pellet size with peak temperature shifted to the smaller pellet sizes. Analyzing the numerical results also showed that for the small pellet sizes, shortening the diffusion path leads to the spreading of the reaction interface. The modeling methodology herein can be applied to any particulate processes and is not limited to the aforementioned case.

The daily gas production of a single well (coalbed methane (CBM) vertical well) in the western Fukang mining area in the southern margin of the Junggar Basin, Xinjiang, China is relatively high. However, there are significant differences between gas and water production of CBM wells at different locations in the area, and the reason has not been adequately explained. To explore the distribution characteristic of coalbed methane and water in the Fukang mining area, the three-phase CBM gas (adsorption gas, free gas, and water-soluble gas) content was determined based on theoretical analysis and simulation. Combining the calculation results and the basis of geological data, the CBM-water differential distribution in the study area was discussed. The results show that the average daily water production and average daily gas production of CBM wells show a negative correlation in the study area. The CBM wells with high daily gas production are mainly located in the high areas of the structure, and these wells commonly begin to produce gas within a short period. The calculation of three-phase CBM gas content and the test results of gas composition show that the gas content (especially the free gas) is relatively high in the high areas of the structure, while the concentration of C2H6 is relatively low. Meanwhile, the concentration of C2H6 shows a positive correlation with buried depth, which indicates that CBM migrates from the deep areas to the higher areas. The calculation of equivalent water level elevation and hydraulic head shows that the groundwater mainly flows from the central part to the east and the west within the CBM well areas, and the groundwater flows downward along the coal seam controlled by gravity, which results in the CBM-water differential distribution. The CBM-water differential distribution in the western Fukang mining area is the result of coupling control of tectonic and hydrological geology factors. Multistage tectonic movements formed large-scale folds and faults in the area, which controlled the migration direction of CBM and groundwater. The dip angle of the stratum in the study area is commonly greater than 45°, and the gravity effect is greater in the process of groundwater flow, which promotes the CBM-water differential distribution. Free gas migrates to the high area of the structure, and groundwater accumulates in the axial part of the syncline. The results in this study provide a basis for the large-dip angle CBM exploration and development in the Fukang mining area.

Molten salt reactors (MSRs) have the potential to safely support green energy goals while meeting baseload energy needs with diverse energy portfolios. While reactor designers have made tremendous strides with these systems, licensing and deployment of these reactors will be aided through the development of new technology such as on-line and remote monitoring tools. Of particular interest is quantifying reactor off-gas species, such as iodine, within off-gas streams to support the design and operational control of off-gas treatment systems. Here, the development of advanced Raman spectroscopy systems for the on-line analysis of gas composition is discussed, focusing on the key control species I2(g). Signal response was explored with two Raman instruments, utilizing 532 and 671 nm excitation sources, as a function of I2(g) pressure and temperature. Also explored is the integration of advanced data analysis methods to enable real-time and highly accurate analysis of complex optical data. Specifically, the application of chemometric modeling is discussed. Raman spectroscopy paired with chemometric analysis is demonstrated to provide a powerful route to analyzing I2(g) composition within the gas phase, which lays the foundation for applications within molten salt reactor off-gas analysis and other significant chemical processes producing iodine species.

The 2-D numerical simulation of the particle motion and combustion behavior in the raceway has been done to analyze the gas-flow field, pressure field, temperature field, distribution of gas composition, as well as the effect of coke mass-flow rate, and blowing gas temperature on the maximum temperature in the raceway zone. The results show that the temperature in the cavity reaches the maximum in the upper part of the cavity region, and the maximum value is above 3000 K. During the combustion process, the concentration of O2 decreases, and the concentration of CO increases. The highest CO content in the gas leaving the raceway zone and entering the coke bed is about 0.95, while the lowest O2 content is 0.05.

A comprehensive three-dimensional (3D) model based on multiphase particle-in-cell (MP-PIC) approach is developed to simulate the co-gasification process of coal and wood in a dual fluidized bed (DFB) system. The pyrolysis of coal and wood, formation and conversion of tar and gaseous pollutants, as well as gasification and combustion reactions are integrated with dense gas-solid flow and heat transfer. The pilot DFB system comprises a bubbling bed gasifier and a fast fluidized bed combustor connected by loop seals. The model correctly predicts profiles of pressure and temperature, the yield and components of the product gas. The gas composition distributions, allocations of particle mass, and solid residence time inside the reactors are explored. The effects of various fuel blend ratios and particle sizes on gasification performances are also investigated. The results show that increasing coal ratio accelerates the steam gasification due to higher char content, which results in the increment of H2 and CO concentrations. The tar content in the product gas continues to decline, while the emissions of NH3 and H2S increase. The size variation of feedstock is not enough to dramatically affect product gas components. The tar content and product gas yield appear a slight upward trend with the smaller size. The variations of NH3 and H2S concentrations are consistent with those of bed temperature.

The effect of a shielding gas on the plasma flow of an electric arc and molten metal is studied. The effect of the shielding gas on the plasma flow of the electric arc of molten metal is simulated, and a mathematical model is developed that describes the flow of the plasma-forming gas inside a device that forms the necessary directions of plasma flows to form a droplet of molten electrode metal of the required size. It is established that the shielding gas and its pressure affect the gas outflow rate and the formation and size of an electrode metal drop. The time of the formation and detachment of the droplet changes at the increase in the pressure of the shielding gas, the higher the gas pressure, the smaller the volume of the droplet. Argon and carbon dioxide have different effects on the plasma flow of the electric arc, the length of the arc, the formation and detachment of the droplet. The process of the droplet formation can be controlled by changing the gas composition, pressure, and gas velocity. It is determined that the gas flow rate increases from 1.2 to 5.2 m/s and the volume of a droplet of molten electrode metal decreases at the increase in the gas flow from 10 to 30 L/min. The droplet volume can be changed on average by 65% depending on the shielding gas.

Gas and water samples were collected from coalbed methane (CBM) wells, rivers, and springs in the southern Junggar Basin (SJB). These samples were analyzed for gas composition, stable isotopes, 16s ribosomal ribonucleic acid sequence, chemical compositions, and radioisotopes. The objective of this study was to understand CBM genesis in the Junggar Basin, the reason for abnormal CO2 accumulation, the development of microbial communities, the source of coalbed water, and the timing of methanogenesis. The CBM genesis is complex in the SJB, but it is closely related to microbial activities. The stagnant zone, which experiences limited groundwater recharge, may represent a relatively closed system where CO2 is easily trapped and the residual CO2 becomes progressively enriched in 13C. Only two families of methanogens (i.e., Methanobacteriaceae and Methanospirillaceae) are present in the coalbed waters, indicating that CO2 reduction is the main pathway for generating microbial gas. The coalbed water samples from the Houxia and Manasi–Hutubi regions plot around the local meteoric water line (LMWL), indicating recharge by modern meteoric water and rivers. However, the samples from the Miquan and Fukang regions plot below the LMWL, reflecting older snowmelt water recharge. Isotopic dating indicates that the age of coalbed water in the Miquan and Fukang regions is 43.5–2000 ka. Early coalification and later hydrological events collectively determined the regional variations in CBM genesis and gas composition in the SJB.

Photoacoustic spectroscopy (PAS) is a sensitive technique for the detection of trace gases and aerosols and measurements of their absorption coefficients. The accuracy of such measurements is often governed by the fidelity of the PAS instrument calibration. Gas samples laden with O3 of a known or independently measured absorption coefficient are a convenient and commonplace route to calibration of PAS instruments operating at visible wavelengths (λ), yet the accuracy of such calibrations remains unclear. Importantly, the photoacoustic detection of O3 in the Chappuis band (λ ∼ 400–700 nm) depends strongly on the timescales for energy transfer from the nascent photoproducts O(3P) and O2(X, v > 0) to translational motion of bath gas species. Significant uncertainties remain concerning the dependence of these timescales on both the sample pressure and the bath gas composition. Here, we demonstrate accurate characterisation of microphone response function dependencies on pressure using a speaker transducer to excite resonant acoustic modes of our photoacoustic cells. These corrections enable measurements of photoacoustic response amplitudes (also referred to as PAS sensitivities) and phase shifts with variation in static pressure and bath gas composition, at discrete visible wavelengths spanning the Chappuis band. We develop and fit a photochemical relaxation model to these measurements to retrieve the associated variations in the aforementioned relaxation timescales for O(3P) and O2(X, v > 0). These timescales enable a full assessment of the accuracy of PAS calibrations using O3-laden gas samples, dependent on the sample pressure, bath gas composition and PAS laser modulation frequency.

Depending on reservoir conditions, composition of reservoir oil and gas agent, various modes of oil displacement by gas can be implemented in reservoir conditions. The most preferable mode from the standpoint of the completeness of oil recovery is the mode of miscible displacement of oil by gas. The main parameter indicating the achievement of the miscible displacement mode is the minimum miscibility pressure. The most popular and reliable laboratory method for determining the minimum mixing pressure is the slim-tube method. The results of laboratory studies performed to determine the value of the minimum miscibility pressure of reservoir oil from the Tolumskoye field and associated petroleum gas of the Semividovskaya group of fields and also to determine the mode of oil displacement by associated petroleum gas are presented. To determine the parameters of reservoir oil and change its properties at various molar concentrations, the standard PVT research technique was used. To determine the minimum miscibility pressure, the slim-tube technique was used. To assess the mechanism of miscibility process development, chromatographic analysis of the sampled gas composition and visual analysis of the phase fluids behavior by means of a visual cell were additionally performed. Two series of filtration experiments were performed to displace the recombined oil model of the Tolumskoye field by the model of associated petroleum gas from the Semividovskaya group of fields on slim models. According to the obtained dependence of the oil displacement coefficient on pressure, when oil from the Tolumskoye field was displaced by associated petroleum gas of the Semividovskaya group of fields, the minimum miscibility pressure would be 14.8 MPa. Based on the criteria for determining the mixing mode, as a result of generalization and comprehensive analysis of the research results, it was found that for the conditions of the Tolumskoye field, the mode of oil displacement by associated petroleum gas of the Semividovskaya group of fields was the mode of the developed multi-contact miscible displacement (the mechanism of condensation of solvent components into the oil phase).

The aim of this work was to use fish processing waste (FW) as main substrate for anaerobic digestion. To enhance the biogas production of FW, co-digestion was done with two other substrates: cow dung (CD) and waste of market (MW). Batch test was carried out in an 1 L glass digester in a temperature controlled chamber at 38°C. The following mixtures were carried out: FW with CD respectively at different ratios 100:0% (A), 80:20% (B) and 60:40% (C); FW with MW at the following ratio 80:20% (D); FW with CD and MW respectively at these ratios 80:10:10% (F) and 60:20:20% (G). The biogas produced was measured using a milligas counter® and the volume of gas was recorded. The gas composition was determined using gas chromatography. With a pH stable for raw substrates and mixtures, TS and VS (%TS) contents for FW were respectively 31.01% and 91.55%. Between 3 to 13 days of experimentation, the highest flow rate was observed. The percentage of methane was more important for mixtures B and D, 61% and 59% respectively. pH and VOA/TIC were stable at the end of the batch test for all mixtures, meaning that the organic matter was already well digested. The highest values of Volatile Solid Removal (VSR) were found for mixtures C, D, F and G. Therefore, the promising mixtures for next experimentations in large scale are B and D.

The conceptual light olefin production system from biomass via gasification and methanol synthesis was simulated and its thermodynamic performance was evaluated through exergy analysis. The system was made up of gasification, gas composition adjustment, methanol synthesis, light olefin synthesis, steam & power generation and cooling water treatment. The in-depth exergy analysis was performed at the levels of system, subsystem and operation component respectively. The gasifier and the tail gas combustor were the main sources of irreversibility with exergy destruction ratios of 17.0% and 16.8% of the input exergy of biomass. The steam & power generation subsystem accounted for 43.4% of the overall exergy destruction, followed by 41.0% and 5.69% in the subsystems of gasification and gas composition adjustment respectively. The sensitivity evaluation of the operation parameters of gasifier indicates that the system efficiency could be improved by enhancing syngas yield and subsequent yield of light olefins. The overall exergetic efficiency of 30.5% is obtained at the mass ratios of steam to biomass and O2-rich gas (95 vol%) to biomass (S/B and O/B) of 0.26 and 0.14 and gasification temperature at 725 °C.

A new approach is demonstrated in which soft experimentation can be performed for MMP measurements, thus replacing the common practice of slim tube displacement laboratory experiments. Recovery potential from oil reservoirs by miscible flue gas injection was studied by slim tube and field-scale numerical simulation using two flue gases and seven crude oils sampled at different depths in three candidate reservoirs. The soft experimentations were conducted using Eclipse300TM, a three-phase compositional simulator. This study investigates minimum miscibility pressure (MMP), a significant miscible gas injection project screening tool. Successful design of the project is contingent to the accurate determination of the MMP. This study evaluates effects of important factors such as injection pressure, oil component composition, and injection gas composition on the MMP and recovery efficiency for slim tube and field-scale displacements. Two applicable MMP correlations were used for comparison and validation purposes.

A flare system in oil platform is a combustion stack used to burn off excess gases that cannot be processed and gases that have to be eliminated in emergency shutdown to avoid the risk of explosion. Gas flow measurement in flares is still considered challenging because the measurement has to attend many specific demands, quite different from any other flow measurement application. For these types of measurements, many sensor technologies are available; however, they are all very expensive, and only a few ones can attend all demands. The objective of this article is to present a flow rate sensor based on fiber Bragg grating (FBG), cross correlation, and heatwave travel time techniques. The system was developed with inexpensive components and is little intrusive, capable of attaining the rangeability of the flare demand and independent of gas composition, pressure, and temperature.

Mercury lamps are typically the major light sources in water treatments. However, the use of mercury has raised some concerns with regard to the Minamata Convention on Mercury. As such, Hg-free microwave discharged electrodeless lamps (MDELs) that incorporate a rare gas and a halogen gas (R/H-MDEL) have been investigated with such Hg-free mixture filler gases as Kr/Cl2, Xe/Cl2, and Kr/Br2 (R/H). Of these, only the Kr/Br2-MDEL lamp is self-ignited at an inner pressure of 15 Torr when irradiated with microwave radiation. Accordingly, a novel Kr/Br2 three-layer MDEL (Kr/Br2-MDEL) photoreactor was fabricated to assess the optimal gas composition and gas pressure toward its performance vis-a-vis the treatment of model wastewaters contaminated with the tartrazine dye in aqueous media and with Escherichia coli (E. coli) bacteria. The extent of degradation of the tartrazine dye and sterilization of E. coli increased with irradiation time, with microwave radiation power (100, 200, and 300 W), and with increased sample flow rate 0.4 L min‒1 to 0.8 L min‒1. The tartrazine-contaminated wastewater was treated at a flow rate of 0.4 L min‒1 for 60 min of microwave irradiation by three different protocols that resulted in UV (62%) >> UV/ROS (24%) > ROS (0%); ROS denotes reactive oxygen species. After 5 min irradiation of the E.coli wastewater, also at 0.4 L min‒1, the order was UV (99.5%) ≈ UV/ROS (99.3%) >> ROS (14.5%). For comparison, the photosterilization of E. coli with an equivalent Hg/Ar-MDEL light source was also nearly complete (99.7%). Thus, the suitability of the environmentally friendlier Kr/Br2 gas fill to replace Hg/Ar filler gas in MDELs for the photoelimination of organic pollutants and microbial disinfection in aqueous media has been demonstrated.

In this study, numerical analysis for downdraft gasifier was performed. The influence of operational parameters such as temperature and equivalence ratio on the composition of producer gas was investigated. The range of temperature was from 750 K to 1150 K with an equivalence ratio of 0.2 to 0.67 were considered for this study. Moisture content of 12% and 7% was identified for Neem leaves and Asoka leaves, respectively. The main gas constituent of producer gas formed during biomass gasification in downdraft gasifier was hydrogen (H2), carbon monoxide (CO), methane (CH4), steam (H2O), carbon dioxide (CO2), and nitrogen (N2).

The angular thermal radiation coefficients and the efficiency of arcs for different distances from them to the walls of electric-arc furnaces of 0.5 to 120 t capacity are calculated. A relationship between the arc efficiency and the specific power consumption of the furnaces is established. The arc efficiency versus the depth of submersion of the arcs into the metal bath and slag in high- and low-capacity electric-arc furnaces is calculated and plotted.

Scuba diving could increase free radicals production which acts as signaling molecules to induce adaptation against oxidative attack. The aim of the new research was to study the impact of scuba diving effects on multiple gas composition responses from the exhaled breath of professional divers. Ethylene, ammonia, and carbon dioxide concentrations from diver s respiration were measured before and after the immersion to 8 m depth in the Black Sea. The ethylene gas (for oxidative stress condition), the ammonia gas (for proteins degradation) and the carbon dioxide gas from the respiration of the six divers were evaluated by mean of the breath test using infrared laser absorption spectroscopy. The experimental results for each breath test of scuba divers will be presented and discussed.