Journal articles: 'Methane number'

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Blankenship, Andrea N., Manoj Ravi, and Jeroen A. van Bokhoven. "Esterification Product Protection Strategies for Direct and Selective Methane Conversion." CHIMIA International Journal for Chemistry 75, no. 4 (April 28, 2021): 305–10. http://dx.doi.org/10.2533/chimia.2021.305.

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A scale-flexible process for the direct and selective oxidation of methane to primary oxygenates is of great interest, however, a commercially feasible approach has yet to be realized due to a number of challenges. Low product yields imposed by a well-established selectivity-conversion limit are particularly burdensome for direct methane-to-methanol chemistry. One strategy that has emerged to break out of this limit is the in situ esterification of produced methanol to the more oxidation-resistant methyl ester. However, these methaneto-methyl-ester approaches still elude commercialization despite their unprecedented high yields. Herein, we outline some of the key barriers that hinder the commercial prospects of this otherwise promising route for highyield direct catalytic methane conversion, including extremely corrosive reagents, homogeneous catalysts, and inviable oxidants. We then highlight directions to address these challenges while maintaining the characteristic high performance of these systems. These discussions support the efficacy of product protection strategies for the direct, selective oxidation of methane and encourage future work in developing creative solutions to merge this promising chemistry with more practical industrial requirements.

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Yudiandika, I. Putu, I. Wayan Suarna, and I. Made Sudarma. "PENGARUH JUMLAH BAKTERI METHANOBACTERIUM DAN LAMA FERMENTASI TERHADAP PROPORSI GAS METANA (CH4) PADA PENGOLAHAN SAMPAH ORGANIK DI TPA SUWUNG DENPASAR." ECOTROPHIC : Jurnal Ilmu Lingkungan (Journal of Environmental Science) 11, no. 1 (May 1, 2017): 29. http://dx.doi.org/10.24843/ejes.2017.v11.i01.p05.

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EFFECT OF NUMBER OF METHANOBACTERIUM AND FERMENTATION DURATION TO METHANE (CH4) GAS PROPORTION IN ORGANIC WASTE PROCESSING IN SUWUNG TPA DENPASARA research has been conducted to find out the effect to the amount of methanobacterium bacteria and fermentation duration toward proportion of methana (CH4) at organic waste processing at TPA Suwung Denpasar. Methana gas produced from this organic waste will be processed become fuel of electric generation. From this study will be expected to get all methana gas that contained at the waste so that there is no methana gas loss to the atmosphere. This study was conducted by using 4 treatments that are without bacteria (B0), bacteria with number of population 106 CFU/ml (B1), bacteria with population of 107 CFU/ml (B2), and bacteria with population of 108 CFU/ml (B3). Each treatment conducted thrice (3) repeat. The four treatments conducted measurement of gas variable after fermentation during 0 week, 3 weeks, 5 weeks, 7 weeks and 9 weeks by uisng gas analyzer GA 2000 Geotech. Data from study result then analyzed by using complicated factorial design (RAL). From ANOVA analysis shows there was significant bacteria number and fermentation duration toward proportion or procentage of methana gas resulted. The longer fermentation time takes place, the bigger the proportion of the methane gas produced. However, the greater number of the bacteria population does not always produce bigger proportion of methane gas To find out the combination which could give best effect the researcher used Duncan test. The result of analysis from Duncan shows that combination at the ninth weeks by number of bacteria 107 CFU/ml giving best result that was percentage of methana gas is 55,10%.

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Malenshek, Martin, and Daniel B. Olsen. "Methane number testing of alternative gaseous fuels." Fuel 88, no. 4 (April 2009): 650–56. http://dx.doi.org/10.1016/j.fuel.2008.08.020.

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Ryan, T. W., T. J. Callahan, and S. R. King. "Engine Knock Rating of Natural Gases—Methane Number." Journal of Engineering for Gas Turbines and Power 115, no. 4 (October 1, 1993): 769–76. http://dx.doi.org/10.1115/1.2906773.

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A procedure has been developed and documented for determining the methane number of gaseous fuels. The methane number provides an indication of the knock tendency of the fuel. An experimental test matrix was designed for quantifying the effects of ethane, propane, butane, and CO2. A unique gas mixing and control system was developed to supply test gases to the engine and to control the equivalence ratio and engine operation. The results of the experiments agreed well with the limited data published in the literature. Predictive equations were developed for the methane number (MN) of gaseous fuels using the gas composition. The forms of these equations are suitable for incorporation in a computer program or a spreadsheet.

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Kussmaul, Martin, Markus Wilimzig, and Eberhard Bock. "Methanotrophs and Methanogens in Masonry." Applied and Environmental Microbiology 64, no. 11 (November 1, 1998): 4530–32. http://dx.doi.org/10.1128/aem.64.11.4530-4532.1998.

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ABSTRACT Methanotrophs were present in 48 of 225 stone samples which were removed from 19 historical buildings in Germany and Italy. The average cell number of methanotrophs was 20 CFU per g of stone, and their activities ranged between 11 and 42 pmol of CH4 g of stone−1 day−1. Twelve strains of methane-oxidizing bacteria were isolated. They belonged to the type II methanotrophs of the genera Methylocystis,Methylosinus, and Methylobacterium. In masonry, growth substrates like methane or methanol are available in very low concentrations. To determine if methane could be produced by the stone at rates sufficient to support growth of methanotrophs, methane production by stone samples under nonoxic conditions was examined. Methane production of 0.07 to 215 nmol of CH4 g of stone−1 day−1 was detected in 23 of 47 stone samples examined. This indicated the presence of the so-called “mini-methane”-producing bacteria and/or methanogenic archaea. Methanotrophs occurred in nearly all samples which showed methane production. This finding indicated that methanotrophs depend on biogenic methane production in or on stone surfaces of historical buildings.

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Kuczyński, Szymon, Mariusz Łaciak, Adam Szurlej, and Tomasz Włodek. "Impact of Liquefied Natural Gas Composition Changes on Methane Number as a Fuel Quality Requirement." Energies 13, no. 19 (September 26, 2020): 5060. http://dx.doi.org/10.3390/en13195060.

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The one of main quality requirements of natural gas as an engine fuel is the methane number (MN). This parameter indicates the fuel’s capability to avoid knocking in the engine. A higher MN value indicates a better natural gas quality for gas engines. Natural gas with higher methane content tends to have higher MN value. This study presents analysis of deviation of liquefied natural gas (LNG) composition and its impact on LNG quality as an engine fuel. The analysis of higher hydrocarbons and nitrogen content impact on LNG parameters was considered for several samples of LNG compositions. Most engine manufacturers want to set a new, lower limit value for methane number at 80. This fact causes significant restrictions on the range of variability in the composition of liquefied natural gas. The goal of this study was to determine the combination of the limit content of individual components in liquefied natural gas to achieve the strict methane number criterion (MN > 80). To fulfill this criterion, the methane content in LNG would have to exceed 93.7%mol, and a significant part of the LNG available on the market does not meet these requirements. The analysis also indicated that the methane number cannot be the only qualitative criterion, as its variability depends strongly on the LNG composition. To determine the applicability of LNG as an engine fuel, the simultaneous application of the methane number and Wobbe index criteria was proposed.

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Islam, Tajul, Maqsud Hossain, Naushin Tabassum, Mahir Amer Haque, Hasan Mahmud Reza, and Lise Øvreås. "Two Novel Thermotolerant Methane Oxidizers from a Tropical Natural Gas Field in Bangladesh." Bangladesh Journal of Microbiology 38, no. 2 (February 6, 2022): 63–71. http://dx.doi.org/10.3329/bjm.v38i2.58104.

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Aerobic thermotolerant methane oxidizers utilize methane as a sole carbon and energy source, and predominantly they are associated with the phylum Proteobacteria. Here we present two further new strains (HGS-45: coccusshaped and HGF-47: rod-shaped and vibrioid) of thermotolerant obligate proteobacterial methanotrophic bacteria, which were isolated from an abandoned tropical natural gas field wet soil sample in the northeast of Bangladesh. Strains are Gram-negative, nonmotile, and capable of growth on methane and methanol as their energy sources. Isolates are thermotolerant and could grow up to 52oC, optimally at 42oC, but show no growth at 55 or 15oC. Based on 16S rRNA gene sequence analyses and phylogenetically, HGS-45 is most closely related to the obligate Type Ib methanotroph Methylococcus capsulatus of the family Methylococcaceae, whereas HGF-47 is affiliated to Type IIa methanotroph Methylocystis sp. of the family Methylocystaceae and possesses Type II intracytoplasmic membrane (ICM) systems. Genes of particulate methane monooxygenase (pMMO) and the methanol dehydrogenase (MDH) were detected by PCR. Southern-blot analyses of genomic DNA from both strains were positive, implying the aerobic biological oxidation process from methane to methanol by the pMMO. Each strain presumably represents a novel species. Furthermore, both strains will increase our knowledge of thermotolerant methanotrophic proteobacterial diversity, cohabitation, and their participation to global carbon cycles as well as signifying biological methane sinks in the terrestrial natural gas field ecosystems. Bangladesh J Microbiol, Volume 38, Number 2, December 2021, pp 63-71

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Inagaki, Fumio, Urumu Tsunogai, Masae Suzuki, Ayako Kosaka, Hideaki Machiyama, Ken Takai, Takuro Nunoura, Kenneth H. Nealson, and Koki Horikoshi. "Characterization of C1-Metabolizing Prokaryotic Communities in Methane Seep Habitats at the Kuroshima Knoll, Southern Ryukyu Arc, by Analyzing pmoA, mmoX, mxaF, mcrA, and 16S rRNA Genes." Applied and Environmental Microbiology 70, no. 12 (December 2004): 7445–55. http://dx.doi.org/10.1128/aem.70.12.7445-7455.2004.

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ABSTRACT Samples from three submerged sites (MC, a core obtained in the methane seep area; MR, a reference core obtained at a distance from the methane seep; and HC, a gas-bubbling carbonate sample) at the Kuroshima Knoll in the southern Ryuku arc were analyzed to gain insight into the organisms present and the processes involved in this oxic-anoxic methane seep environment. 16S rRNA gene analyses by quantitative real-time PCR and clone library sequencing revealed that the MC core sediments contained abundant archaea (∼34% of the total prokaryotes), including both mesophilic methanogens related to the genus Methanolobus and ANME-2 members of the Methanosarcinales, as well as members of the δ-Proteobacteria, suggesting that both anaerobic methane oxidation and methanogenesis occurred at this site. In addition, several functional genes connected with methane metabolism were analyzed by quantitative competitive-PCR, including the genes encoding particulate methane monooxygenase (pmoA), soluble methane monooxygenase (mmoX), methanol dehydrogenese (mxaF), and methyl coenzyme M reductase (mcrA). In the MC core sediments, the most abundant gene was mcrA (2.5 × 106 copies/g [wet weight]), while the pmoA gene of the type I methanotrophs (5.9 × 106 copies/g [wet weight]) was most abundant at the surface of the MC core. These results indicate that there is a very complex environment in which methane production, anaerobic methane oxidation, and aerobic methane oxidation all occur in close proximity. The HC carbonate site was rich in γ-Proteobacteria and had a high copy number of mxaF (7.1 × 106 copies/g [wet weight]) and a much lower copy number of the pmoA gene (3.2 × 102 copies/g [wet weight]). The mmoX gene was never detected. In contrast, the reference core contained familiar sequences of marine sedimentary archaeal and bacterial groups but not groups specific to C1 metabolism. Geochemical characterization of the amounts and isotopic composition of pore water methane and sulfate strongly supported the notion that in this zone both aerobic methane oxidation and anaerobic methane oxidation, as well as methanogenesis, occur.

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Dec, Steven F., Kristin E. Bowler, Laura L. Stadterman, Carolyn A. Koh, and E. Dendy Sloan. "Direct Measure of the Hydration Number of Aqueous Methane." Journal of the American Chemical Society 128, no. 2 (January 2006): 414–15. http://dx.doi.org/10.1021/ja055283f.

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Tjojudo, Danianto Hendragiri, and Sutrasno Kartohardjono. "Methane Number Improvement of Gas from LNG Regasification Unit." E3S Web of Conferences 67 (2018): 04033. http://dx.doi.org/10.1051/e3sconf/20186704033.

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Methane Number (MN) is one of quality requirement of gas as fuel for gas engine, which indicates fuel capability to avoid knocking in the engine. Higher MN provides better quality of gas for gas engine. Natural gas with higher methane (CH4) and fewer higher hydrocarbon, tends to have higher MN score. This study aims to obtain heating methods of LNG to produce vapor that has appropriate MN as a fuel gas supply to gas engine. The simulation for LNG regasification prepared is an approach to the design of the existing regasification facility of the power plant in Bali. The temperature ranges for LNG heating simulation were obtained based on saturated temperatures of LNG phase envelopes. In the simulation. to obtain a certain MN value can be conducted by adjusting the temperatures at two different values i.e. above -110 ° and below - 80 °. To produce LNG vapor that has MN of 80 either through higher temperature of heating (HT heating) or lower temperature of heating (LT heating) requires more energy than direct heating without MN improvement. Heat loading for LT heating is higher than HT heating due to more temperature defference between LT and heating fluid temperatures. The ability of engine to produce power decreased with decreasing fuel gas MN. The power increment increases for lower MN gas if MN improvement is conducted.

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Uchida, Tsutomu, Takashi Hirano, Takao Ebinuma, Hideo Narita, Kazutoshi Gohara, Shinji Mae, and Ryo Matsumoto. "Raman spectroscopic determination of hydration number of methane hydrates." AIChE Journal 45, no. 12 (December 1999): 2641–45. http://dx.doi.org/10.1002/aic.690451220.

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Sarothi Roy, Partho, Christopher Ryu, Sang Keun Dong, and Chan Seung Park. "Development of a natural gas Methane Number prediction model." Fuel 246 (June 2019): 204–11. http://dx.doi.org/10.1016/j.fuel.2019.02.116.

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Didmanidze, Otari, Aleksandr Afanasev, and Ramil Khakimov. "Natural gas methane number and its influence on the gas engine working process efficiency." Записки Горного института 251 (October 29, 2021): 730–37. http://dx.doi.org/10.31897/pmi.2021.5.12.

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The natural gas usage as a vehicle fuel in the mining industry is one of the priority tasks of the state. The article pays special attention to the component composition of natural gas from the point of view of its thermal efficiency during combustion in the combustion chamber of a power plant on a heavy-duty vehicle in difficult quarry conditions. For this, domestic and foreign methods for determining the main indicator characterizing the knock resistance of fuel in the combustion process – the methane number – are considered. Improvement of technical and economic indicators will be carried out by changing the composition of the gas mixture based on methane to fit the design features of the gas power plant, the methane number will be the determining indicator. A theoretical analysis of the influence of the methane number on such engine parameters as the compression ratio and the maximum speed of the flame front propagation in the second phase of combustion in the engine cylinder, expressed through the angle of rotation of the crankshaft, is presented. Based on the results of theoretical and experimental studies, the dependences of the influence of the methane number on the efficiency of the working process of the engine and its external speed characteristic were obtained.

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Wu, Zhenkuo, Christopher J. Rutland, and Zhiyu Han. "Numerical evaluation of the effect of methane number on natural gas and diesel dual-fuel combustion." International Journal of Engine Research 20, no. 4 (February 22, 2018): 405–23. http://dx.doi.org/10.1177/1468087418758114.

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Natural gas and diesel dual-fuel combustion is a promising technology for efficiently utilizing natural gas in a compression ignition engine. Natural gas composition varies depending on the geographical source, which affects engine performance. The methane number is an indicator of natural gas fuel quality to assess the variation in composition. In this study, the influences of methane number on natural gas/diesel dual-fuel combustion were numerically examined using computational fluid dynamic simulations. The differences between natural gases with the same methane number but different components were also compared. Two dual-fuel combustion strategies, diesel pilot ignition, and reactivity controlled compression ignition were evaluated. The results show that for both diesel pilot ignition and reactivity controlled compression ignition, the ignition delay increases and the combustion duration decreases as the methane number is increased. The retarded trend of ignition of reactivity controlled compression ignition is more significant than that of diesel pilot ignition, while the decreased trend in combustion duration is less significant. To understand this trend, a chemical kinetics study of ignition delay characteristic of natural gas and n-heptane mixture was conducted. The result reveals that introducing ethane, propane, or an ethane–propane mixture into pure methane shortens the ignition delay in the entire temperature range. However, for the methane and n-heptane mixture, adding ethane, or propane, or an ethane–propane mixture shortens the ignition delay in the high temperature range, while increases the ignition delay in the low temperature range. These observations in combination with the analysis of air–fuel mixture formation and combustion provide the evidence to interpret the different ignition and combustion behaviors between diesel pilot ignition and reactivity controlled compression ignition combustion. In addition, a temperature A-factor sensitivity study was carried out to explain the result of the chemical kinetics study. Furthermore, the responses of emissions to methane number were also investigated. The results show that for diesel pilot ignition, the hydrocarbon and carbon monoxide emissions decrease with the decreased methane number. However, for reactivity controlled compression ignition, the variations of hydrocarbon and carbon monoxide emissions with the methane number are not so obvious as for diesel pilot ignition combustion. For both diesel pilot ignition and reactivity controlled compression ignition combustion, the nitrogen oxides emissions show a strong dependence on combustion phasing rather than natural gas composition. Overall, to control diesel pilot ignition combustion, the methane number should be considered together with other parameters. However, attention should be paid to other control parameters for the reactivity controlled compression ignition combustion. The engine performance of reactivity controlled compression ignition is not sensitive to the variation of natural gas composition, so it can adapt to the natural gas from different sources.

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M. Sauer, Vinicius, and Derek Dunn-Rankin. "Impinging nonpremixed coflow methane–air flames with unity Lewis number." Proceedings of the Combustion Institute 36, no. 1 (2017): 1411–19. http://dx.doi.org/10.1016/j.proci.2016.06.193.

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Zhang, Shiran, Yuting Li, Ziyun Wang, Yu Tang, Xing Huang, Stephen D. House, Hao Huang, et al. "Coordination Number-Dependent Complete Oxidation of Methane on NiO Catalysts." ACS Catalysis 11, no. 15 (July 20, 2021): 9837–49. http://dx.doi.org/10.1021/acscatal.1c01455.

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Holewa-Rataj, Jadwiga, and Ewa Kukulska-Zając. "Wpływ dodatku wodoru na liczbę metanową gazu ziemnego." Nafta-Gaz 76, no. 12 (December 2020): 945–50. http://dx.doi.org/10.18668/ng.2020.12.08.

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Liczba metanowa jest istotnym parametrem charakteryzującym paliwa silnikowe. Wartość liczby metanowej określa podatność paliwa na spalanie stukowe, przy czym im wartość ta jest większa, tym większa jest odporność paliwa na spalanie stukowe. Gaz ziemny należący do grupy H powinien charakteryzować się minimalną liczbą metanową powyżej 65 (PN-EN 16726:2018). W doniesieniach literaturowych dominuje z kolei pogląd, że ze względu na efektywność pracy silnika oraz niską emisję szkodliwych substancji optymalna wartość liczby metanowej dla gazów spalanych w silnikach samochodowych zasilanych gazem CNG lub LNG powinna wynosić powyżej 80. W dobie dążenia do ograniczenia zużycia i zastępowania paliw kopalnych odnawialnymi źródłami energii (OZE) istotne jest sprawdzenie, jak duży wpływ na wartość liczby metanowej gazu ziemnego będzie miało dodanie do niego wodoru, który od kilku już lat znajduje się w centrum uwagi jako doskonały nośnik energii i tzw. czyste paliwo i dla którego przyjęto zerową wartość liczby metanowej. W artykule omówiono wpływ dodatku wodoru do gazu ziemnego na wartość liczby metanowej powstającej mieszaniny, w odniesieniu do minimalnej i optymalnej wartości liczby metanowej. Podczas analizy wykorzystano dane dotyczące 19 różnych składów gazu ziemnego, charakteryzujące gaz ziemny należący do grupy E pochodzący z polskiej sieci dystrybucyjnej. Wyniki przeprowadzonych obliczeń pozwalają stwierdzić, że dodanie wodoru do gazu ziemnego, w ilości pozwalającej na zachowanie parametrów fizykochemicznych gazu określonych w odpowiednich normach, powoduje obniżenie wartości liczby metanowej powstałej mieszaniny gaz ziemny–wodór maksymalnie o 22,1%. Należy dodać, że w żadnym z analizowanych przypadków uzyskana wartość liczby metanowej nie była niższa niż wartość minimalna wynosząca 65. W odniesieniu z kolei do optymalnej wartości liczby metanowej dla paliw gazowych można stwierdzić, że dodatek wodoru do gazu ziemnego, z zachowaniem przyjętych założeń w zakresie parametrów energetycznych i gęstości gazu, może powodować zwiększenie właściwości stukowych powstałej mieszaniny i przyczyniać się do tego, że nie będzie ona optymalnym paliwem. Przeprowadzone obliczenia i analizy wykazały także, że zmiana wartości liczby metanowej mieszaniny gaz ziemny–wodór jest proporcjonalna w stosunku do ilości wodoru wprowadzonego do gazu ziemnego.

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Haitl, Martina, Tomáš Vítěz, Tomáš Koutný, Radovan Kukla, Tomáš Lošák, and Ján Gaduš. "Use of G-phase for biogas production." Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis 60, no. 6 (2012): 89–96. http://dx.doi.org/10.11118/actaun201260060089.

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Biogas is very promising renewable energy resource. The number of biogas plants increase every year. Currently there is a demand for new ways of organic waste treatment from production of different commodities. One of the technologies which produce waste is biodiesel production. One of the wastes from the biodiesel production is G-phase which is mainly consisted from glycerol and methanol. The aim of work was to find the effect of G-phase addition, to fermented material, on biogas resp. methane production. Two lab-scale batch anaerobic fermentation tests (hydraulic retention time 14 and 22 days) under mesophilic temperature conditions 38.5 °C have been performed. The positive effect of G-phase addition to methane production has been found. G-phase was added in three different amounts of inoculums volume 0.5 %, 1% and 1.5 %. The highest absolute methane production has been achieved by 1.5 % addition of G-phase. However it was also found difference in specific methane production due to use of different inoculum consisted of swine or cow manure. The specific methane production in hydraulic retention time of 14 days has been for the same G-phase dose 1.5 % higher for swine manure, 0.547 m3∙kg−1 of organics solids compare with cow liquid manure 0.474 m3∙kg−1 of organics solids.

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Peterson, Joseph R., Piyush Labhsetwar, Jeremy R. Ellermeier, Petra R. A. Kohler, Ankur Jain, Taekjip Ha, William W. Metcalf, and Zaida Luthey-Schulten. "Towards a Computational Model of a Methane Producing Archaeum." Archaea 2014 (2014): 1–18. http://dx.doi.org/10.1155/2014/898453.

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Progress towards a complete model of the methanogenic archaeumMethanosarcina acetivoransis reported. We characterized size distribution of the cells using differential interference contrast microscopy, finding them to be ellipsoidal with mean length and width of 2.9 μm and 2.3 μm, respectively, when grown on methanol and 30% smaller when grown on acetate. We used the single molecule pull down (SiMPull) technique to measure average copy number of the Mcr complex and ribosomes. A kinetic model for the methanogenesis pathways based on biochemical studies and recent metabolic reconstructions for several related methanogens is presented. In this model, 26 reactions in the methanogenesis pathways are coupled to a cell mass production reaction that updates enzyme concentrations. RNA expression data (RNA-seq) measured for cell cultures grown on acetate and methanol is used to estimate relative protein production per mole of ATP consumed. The model captures the experimentally observed methane production rates for cells growing on methanol and is most sensitive to the number of methyl-coenzyme-M reductase (Mcr) and methyl-tetrahydromethanopterin:coenzyme-M methyltransferase (Mtr) proteins. A draft transcriptional regulation network based on known interactions is proposed which we intend to integrate with the kinetic model to allow dynamic regulation.

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Puente, David, Fco Javier Gracia, and Isabel Ayerdi. "Thermal conductivity microsensor for determining the Methane Number of natural gas." Sensors and Actuators B: Chemical 110, no. 2 (October 2005): 181–89. http://dx.doi.org/10.1016/j.snb.2005.01.026.

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Schiffgens, H. J., H. Endres, H. Wackertapp, and E. Schrey. "Concepts for the Adaptation of SI Gas Engines to Changing Methane Number." Journal of Engineering for Gas Turbines and Power 116, no. 4 (October 1, 1994): 733–39. http://dx.doi.org/10.1115/1.2906880.

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In a joint project of FEV Motorentechnik and Ruhrgas AG, the design of stoichiometric and lean-burn Otto engines was optimized by selective modifications to the design and operating parameters to accommodate changing methane numbers (LPG addition to CNG). Of particular importance was knock-free engine operation at a low NOx output to meet the requirements of the German Clean Air Code while concurrently achieving both high efficiencies and mean effective pressures. Based upon the results obtained, concepts for the control of Otto-cycle gas engines to accept changing methane numbers were developed. The newly developed gas engine control device allows these concepts to meet the requirement of the German Clean Air Code with economically viable conditions while preventing engine knock. Furthermore, the test results show that dedicated Otto-cycle gas engines can meet the most stringent emission limits for commercial vehicles while maintaining high efficiencies.

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Kelley, Cheryl A., Brooke E. Nicholson, Claire S. Beaudoin, Angela M. Detweiler, and Brad M. Bebout. "Trimethylamine and Organic Matter Additions Reverse Substrate Limitation Effects on the δ13C Values of Methane Produced in Hypersaline Microbial Mats." Applied and Environmental Microbiology 80, no. 23 (September 19, 2014): 7316–23. http://dx.doi.org/10.1128/aem.02641-14.

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ABSTRACTMethane production has been observed in a number of hypersaline environments, and it is generally thought that this methane is produced through the use of noncompetitive substrates, such as the methylamines, dimethylsulfide and methanol. Stable isotope measurements of the produced methane have also suggested that the methanogens are operating under conditions of substrate limitation. Here, substrate limitation in gypsum-hosted endoevaporite and soft-mat hypersaline environments was investigated by the addition of trimethylamine, a noncompetitive substrate for methanogenesis, and dried microbial mat, a source of natural organic matter. The δ13C values of the methane produced after amendments were compared to those in unamended control vials. At all hypersaline sites investigated, the δ13C values of the methane produced in the amended vials were statistically lower (by 10 to 71‰) than the unamended controls, supporting the hypothesis of substrate limitation at these sites. When substrates were added to the incubation vials, the methanogens within the vials fractionated carbon isotopes to a greater degree, resulting in the production of more13C-depleted methane. Trimethylamine-amended samples produced lower methane δ13C values than the mat-amended samples. This difference in the δ13C values between the two types of amendments could be due to differences in isotope fractionation associated with the dominant methane production pathway (or substrate used) within the vials, with trimethylamine being the main substrate used in the trimethylamine-amended vials. It is hypothesized that increased natural organic matter in the mat-amended vials would increase fermentation rates, leading to higher H2concentrations and increased CO2/H2methanogenesis.

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Hwang, Soon-kyu, and Byung-gun Jung. "Methane Number Control of Fuel Gas Supply System Using Combined Cascade/Feed-Forward Control." Journal of Marine Science and Engineering 8, no. 5 (April 28, 2020): 307. http://dx.doi.org/10.3390/jmse8050307.

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Liquefied natural gas began to attract attention as a ship fuel to reduce environmental pollution and increase energy efficiency. During this period, highly efficient internal combustion engines emerged as the new propulsion system instead of steam turbines. However, Otto-cycle engines must use fuel that meets the methane number that was given by the engine makers. The purpose of this study was to develop a system configuration and a control method of methane number adjustment using combined cascade/feed-forward controllers for marine Otto-cycle engines to improve reference tracking and the disturbance rejection. The main principle involves controlling the downstream gas temperature of the fuel gas supply system to meet the required methane number. Three controllers are used in the combined cascade/feed-forward control for adjusting the downstream of the gas temperature: the cascade loop has two controllers and the feed-forward has one controller. The two controllers in the cascade loop are designed with proportional–integral (PI) controllers. The remaining controller is based on feed-forward control theory. A simulation was conducted to verify the efficacy of the proposed method, focusing on the disturbance rejection and set-point tracking, in comparison with a single PI controller, a single PI controller with feed-forward, and cascade control.

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Lee, Sunggeun, and Hankwon Lim. "Variation of the Number of Heat Sources in Methane Dry Reforming: A Computational Fluid Dynamics Study." International Journal of Chemical Engineering 2021 (November 24, 2021): 1–15. http://dx.doi.org/10.1155/2021/4737513.

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To overcome the weak point of the gas type heating (failure in heating uniformly and persistently), liquid type molten salt as a concentration of solar energy was considered as a heat source for dry reforming. This high-temperature molten salt flowing through the center of the tubular reactor supplies necessary heat. The dependence on the number of heat source of the hydrogen production was investigated under the assumption of the fixed volume of the catalyst bed. By changing these numbers, we numerically investigated the methane conversion and hydrogen flow rate to find the best performance. The results showed that the methane conversion performance and hydrogen flow rate improved in proportion to the number of heating tubes. For the one heat source, the reactor surrounded by a heat source rather than that located in the center is the best in terms of hydrogen yield. In addition, this study considered the case in which the system is divided into several smaller reactors of equal sizes and a constant amount of catalyst. In these reactors, we saw that the methane conversion and hydrogen flow rate were reduced. The results indicate that the installation of as many heating tubes as possible is preferable.

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Sudakov, I. A., and S. A. Vakulenko. "Mathematical modelling of positive carbon-climate feedback: permafrost lake methane emission case." Earth System Dynamics Discussions 3, no. 1 (April 4, 2012): 235–57. http://dx.doi.org/10.5194/esdd-3-235-2012.

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Abstract. The permafrost methane emission problem is in the focus of attention of different climate models. We present new approach to the permafrost methane emission modeling. The tundra permafrost lakes is potential source of methane emission. Typically, tundra landscape contains a number of small lakes and warming leads to lake extension. We are making use of this process by the nonlinear theory of phase transitions. We find that climate catastrophe possibility depends on a feedback coefficient connecting the methane concentration in atmosphere and temperature, and on the tundra permafrost methane pool.

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Topp, Edward, and Elizabeth Pattey. "Soils as sources and sinks for atmospheric methane." Canadian Journal of Soil Science 77, no. 2 (May 1, 1997): 167–77. http://dx.doi.org/10.4141/s96-107.

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Methane is considered to be a significant greenhouse gas. Methane is produced in soils as the end product of the anaerobic decomposition of organic matter. In the absence of oxygen, methane is very stable, but under aerobic conditions it is mineralized to carbon dioxide by methanotrophic bacteria. Soil methane emissions, primarily from natural wetlands, landfills and rice paddies, are estimated to represent about half of the annual global methane production. Oxidation of atmospheric methane by well-drained soils accounts for about 10% of the global methane sink. Whether a soil is a net source or sink for methane depends on the relative rates of methanogenic and methanotrophic activity. A number of factors including pH, Eh, temperature and moisture content influence methane transforming bacterial populations and soil fluxes. Several techniques are available for measuring methane fluxes. Flux estimation is complicated by spatial and temporal variability. Soil management can impact methane transformations. For example, landfilling of organic matter can result in significant methane emissions, whereas some cultural practices such as nitrogen fertilization inhibit methane oxidation by agricultural soils. Key words: Methane, methanogenesis, methane oxidation, soil, flux measurement

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Inaba, Satoshi. "Acid–Base Catalytic Effects on Reduction of Methanol in Hot Water." Catalysts 9, no. 4 (April 21, 2019): 373. http://dx.doi.org/10.3390/catal9040373.

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We have performed a number of quantum chemical simulations to examine the reduction process of methanol in hot water. Methanol is converted into a methane by capturing a hydrogen molecule and leaving a water molecule behind. The required energy for the reduction is too high to proceed in the gas phase. The energy barrier for the reduction of methanol is reduced by the catalytic effect of water molecules when we consider the reduction in aqueous solution. However, the calculated reduction rate is still much slower than that found experimentally. The ion product of water tends to increase in hot water, even though it eventually decreases at the high temperature of supercritical water. It is valuable to consider the acid–base catalytic effects on the reduction of methanol in hot water. The significant reduction of the energy barrier is accomplished by the acid–base catalytic effects due to hydronium or hydroxyde. Mean collision time between a hydronium and a methanol in hot water is shorter than the reduction time, during which a methanol is converted into a methane. The calculated reduction rate with the acid–base catalytic effects agrees well with that determined by laboratory experiments. The present study reveals a crucial role of the acid–base catalytic effects on reactions in hot water.

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Xu, Jiabao, Ping Jin, Ruizhi Li, Jue Wang, and Guobiao Cai. "Numerical Study on Combustion and Atomization Characteristics of Coaxial Injectors for LOX/Methane Engine." International Journal of Aerospace Engineering 2021 (May 22, 2021): 1–16. http://dx.doi.org/10.1155/2021/6670813.

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The LOX/methane engine has an admirable performance under a supercritical state. However, the properties of methane change drastically with varying injection temperature. Because the injector can greatly affect the atomization and combustion, this study performed a three-dimensional numerical simulation of atomization, combustion, and heat transfer in a subscale LOX/methane engine to evaluate the effect of the main fluid parameters with different methane injection temperatures and different injectors on atomization performance and combustion performance. The results show that the larger propellant momentum ratio and Weber number can improve the heat flux and combustion stability in shear coaxial injector, while the influence in swirl coaxial injector is relatively small. Moreover, in shear coaxial injector and in swirl coaxial injector, the larger propellant momentum ratio and Weber number can reduce the droplet size, enhance atomization performance, and improve the combustion efficiency. The numerical model provides an economical method to evaluate the main fluid parameters and proposes new design principles of injectors in LOX/methane engine.

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Wang, Y., M. Y. Gu, and L. Cao. "Soot formation in methane-ethylene binary fuel combustion with hydrogen addition." Journal of Physics: Conference Series 2208, no. 1 (March 1, 2022): 012017. http://dx.doi.org/10.1088/1742-6596/2208/1/012017.

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Abstract A numerical investigation of soot formation was conducted by applying the reactive molecular dynamics, and the chemical effect of H2 addition on the soot formation was explored. It was found that a higher initial methane ratio under the same hydrogen doping ratio could accelerate the rate of methane consumption and hydrogen generation As the proportion of methane in the methane-ethylene binary fuel increased, the chemical effect of H2 on the carbon number of the largest soot particles gradually weakened. Quantitative analysis showed that there was almost no coupling effect of hydrogen addition in the methane-ethylene binary fuel.

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Wang, Liu, Xue Rui Ma, Jing Han Wang, Yu Ting Zhou, and Xun Liu. "Favorable Areas Prediction in Jixi Basin." Applied Mechanics and Materials 733 (February 2015): 100–103. http://dx.doi.org/10.4028/www.scientific.net/amm.733.100.

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Based on coalbed methane geology theory, make use of coal and oil drilling data, from both of the coal reservoir characteristics and conservation conditions, Through comparative analysis of a number of geological factors of coalbed thickness, burial depth, metamorphic grade, gas content, roof and floor lithology, dip angle, etc, and found that there are many similarities between Jixi Basin and Black Warrior Basin in the United States of coalbed methane reservoir conditions. Furthermore, referred the domestic and abroad coalbed methane mining experience, a number of geological factors of Jixi Basin were made grading evaluation, optimized favorable blocks, and we found that the favorable coalbed methane target area are the F and H in the south of the basin, and the F block can be used as the preferred favorable coal exploration area.

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Sánchez-Sanz, M., B. A. V. Bennett, M. D. Smooke, and A. Liñán. "Influence of Strouhal number on pulsating methane–air coflow jet diffusion flames." Combustion Theory and Modelling 14, no. 3 (July 9, 2010): 453–78. http://dx.doi.org/10.1080/13647830.2010.490048.

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Zhu, Baoli, Gijs van Dijk, Christian Fritz, Alfons J. P. Smolders, Arjan Pol, Mike S. M. Jetten, and Katharina F. Ettwig. "Anaerobic Oxidization of Methane in a Minerotrophic Peatland: Enrichment of Nitrite-Dependent Methane-Oxidizing Bacteria." Applied and Environmental Microbiology 78, no. 24 (October 5, 2012): 8657–65. http://dx.doi.org/10.1128/aem.02102-12.

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ABSTRACTThe importance of anaerobic oxidation of methane (AOM) as a methane sink in freshwater systems is largely unexplored, particularly in peat ecosystems. Nitrite-dependent anaerobic methane oxidation (n-damo) was recently discovered and reported to be catalyzed by the bacterium “CandidatusMethylomirabilis oxyfera,” which is affiliated with the NC10 phylum. So far, several “Ca. Methylomirabilis oxyfera” enrichment cultures have been obtained using a limited number of freshwater sediments or wastewater treatment sludge as the inoculum. In this study, using stable isotope measurements and porewater profiles, we investigated the potential of n-damo in a minerotrophic peatland in the south of the Netherlands that is infiltrated by nitrate-rich ground water. Methane and nitrate profiles suggested that all methane produced was oxidized before reaching the oxic layer, and NC10 bacteria could be active in the transition zone where countergradients of methane and nitrate occur. Quantitative PCR showed high NC10 bacterial cell numbers at this methane-nitrate transition zone. This soil section was used to enrich the prevalent NC10 bacteria in a continuous culture supplied with methane and nitrite at anin situpH of 6.2. An enrichment of nitrite-reducing methanotrophic NC10 bacteria was successfully obtained. Phylogenetic analysis of retrieved 16S rRNA andpmoAgenes showed that the enriched bacteria were very similar to the ones foundin situand constituted a new branch of NC10 bacteria with an identity of less than 96 and 90% to the 16S rRNA andpmoAgenes of “Ca. Methylomirabilis oxyfera,” respectively. The results of this study expand our knowledge of the diversity and distribution of NC10 bacteria in the environment and highlight their potential contribution to nitrogen and methane cycles.

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Gómez Montoya, Juan Pablo, Andrés A. Amell, and Daniel B. Olsen. "Prediction and measurement of the critical compression ratio and methane number for blends of biogas with methane, propane and hydrogen." Fuel 186 (December 2016): 168–75. http://dx.doi.org/10.1016/j.fuel.2016.08.064.

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Niewiadomski, Adam, Henryk Badura, Tanyana N. Ivanova, Alexandr Repko, and Nikitin R. Yury. "Analysis of Methane Concentration Distribution at U-Ventilated Longwall Outlet – Case Study." New Trends in Production Engineering 3, no. 1 (August 1, 2020): 149–68. http://dx.doi.org/10.2478/ntpe-2020-0013.

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AbstractThe methane hazard concerns a growing number of longwalls in the Polish coal mining industry each year. Mitigating this hazard, both of work safety and economic reasons requires the application of preventive measures adequate to its level. Commonly threat level is estimated based on registered methane concentrations, which fluctuate and highly depends on the place of measurement. The article presents studies on the average and maximum methane concentrations at the longwall outlet, including analyses of the interdependence of methane concentration in methanometry sensors installation locations.

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Choi, Changhyeok, Sungho Yoon, and Yousung Jung. "Shifting the scaling relations of single-atom catalysts for facile methane activation by tuning the coordination number." Chemical Science 12, no. 10 (2021): 3551–57. http://dx.doi.org/10.1039/d0sc05632d.

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Rey, Atxaerandio, Ruiz, Ugarte, González-Recio, Garcia-Rodriguez, and Goiri. "Comparison Between Non-Invasive Methane Measurement Techniques in Cattle." Animals 9, no. 8 (August 15, 2019): 563. http://dx.doi.org/10.3390/ani9080563.

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The aim of this trial was to study the agreement between the non-dispersive infrared methane analyzer (NDIR) method and the hand held laser methane detector (LMD). Methane (CH4) was measured simultaneously with the two devices totaling 164 paired measurements. The repeatability of the CH4 concentration was greater with the NDIR (0.42) than for the LMD (0.23). However, for the number of peaks, repeatability of the LMD was greater (0.20 vs. 0.14, respectively). Correlation was moderately high and positive for CH4 concentration (0.73 and 0.74, respectively) and number of peaks (0.72 and 0.72, respectively), and the repeated measures correlation and the individual-level correlation were high (0.98 and 0.94, respectively). A moderate concordance correlation coefficient was observed for the CH4 concentration (0.62) and for the number of peaks (0.66). A moderate-high coefficient of individual agreement for the CH4 concentration (0.83) and the number of peaks (0.77) were observed. However, CH4 concentrations population means and all variance components differed between instruments. In conclusion, methane concentration measurements obtained by means of NDIR and LMD cannot be used interchangeably. The joint use of both methods could be considered for genetic selection purposes or for mitigation strategies only if sources of disagreement, which result in different between-subject and within-subject variabilities, are identified and corrected for.

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Rasmussen, J., and A. Harrison. "The Benefits of Supplementary Fat in Feed Rations for Ruminants with Particular Focus on Reducing Levels of Methane Production." ISRN Veterinary Science 2011 (August 29, 2011): 1–10. http://dx.doi.org/10.5402/2011/613172.

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Methane (CH4), a highly potent greenhouse gas, has repeatedly been identified as a significant contributor to global warming. In this connection, ruminants, animals that produce large quantities of methane, have been singled out as an area for reduction with regard to their emissions to the atmosphere. In an analysis of recently published data, we identify the underlying mechanisms of methane production in ruminants and focus on the efficacy of different fat sources in terms of their ability to reduce methane production. Specific attention has been placed on in vivo studies involving cattle and sheep, as well as studies based on a large number of animals (>10), recorded over a longer period (>21 days), and employing reliable techniques for the quantification of methane production. Data clearly indicate that supplementary fat, given to ruminants inhibits methane production, with medium-chain fatty acids (laurin, myristic acid) as well as poly-unsaturated fatty acids (linoleic and especially linolenic acid) having a significant effect. It is also apparent that conflicting findings between individual published trials can largely be resolved when one takes into consideration differences in experimental design, the composition of the basic feeds, the fat sources used, and the number of animals involved.

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Hook, Sarah E., André-Denis G. Wright, and Brian W. McBride. "Methanogens: Methane Producers of the Rumen and Mitigation Strategies." Archaea 2010 (2010): 1–11. http://dx.doi.org/10.1155/2010/945785.

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Methanogens are the only known microorganisms capable of methane production, making them of interest when investigating methane abatement strategies. A number of experiments have been conducted to study the methanogen population in the rumen of cattle and sheep, as well as the relationship that methanogens have with other microorganisms. The rumen methanogen species differ depending on diet and geographical location of the host, as does methanogenesis, which can be reduced by modifying dietary composition, or by supplementation of monensin, lipids, organic acids, or plant compounds within the diet. Other methane abatement strategies that have been investigated are defaunation and vaccines. These mitigation methods target the methanogen population of the rumen directly or indirectly, resulting in varying degrees of efficacy. This paper describes the methanogens identified in the rumens of cattle and sheep, as well as a number of methane mitigation strategies that have been effectivein vivo.

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Kang, Mary, Shanna Christian, Michael A. Celia, Denise L. Mauzerall, Markus Bill, Alana R. Miller, Yuheng Chen, Mark E. Conrad, Thomas H. Darrah, and Robert B. Jackson. "Identification and characterization of high methane-emitting abandoned oil and gas wells." Proceedings of the National Academy of Sciences 113, no. 48 (November 14, 2016): 13636–41. http://dx.doi.org/10.1073/pnas.1605913113.

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Recent measurements of methane emissions from abandoned oil/gas wells show that these wells can be a substantial source of methane to the atmosphere, particularly from a small proportion of high-emitting wells. However, identifying high emitters remains a challenge. We couple 163 well measurements of methane flow rates; ethane, propane, andn-butane concentrations; isotopes of methane; and noble gas concentrations from 88 wells in Pennsylvania with synthesized data from historical documents, field investigations, and state databases. Using our databases, we (i) improve estimates of the number of abandoned wells in Pennsylvania; (ii) characterize key attributes that accompany high emitters, including depth, type, plugging status, and coal area designation; and (iii) estimate attribute-specific and overall methane emissions from abandoned wells. High emitters are best predicted as unplugged gas wells and plugged/vented gas wells in coal areas and appear to be unrelated to the presence of underground natural gas storage areas or unconventional oil/gas production. Repeat measurements over 2 years show that flow rates of high emitters are sustained through time. Our attribute-based methane emission data and our comprehensive estimate of 470,000–750,000 abandoned wells in Pennsylvania result in estimated state-wide emissions of 0.04–0.07 Mt (1012g) CH4per year. This estimate represents 5–8% of annual anthropogenic methane emissions in Pennsylvania. Our methodology combining new field measurements with data mining of previously unavailable well attributes and numbers of wells can be used to improve methane emission estimates and prioritize cost-effective mitigation strategies for Pennsylvania and beyond.

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Kim, Chungwoo, Denver I. Walitang, Aritra Roy Choudhury, Yi Lee, Sanghun Lee, Hyenchung Chun, Tae-Young Heo, Kido Park, and Tongmin Sa. "Changes in Soil Chemical Properties Due to Long-Term Compost Fertilization Regulate Methane Turnover Related Gene Abundances in Rice Paddy." Applied Sciences 12, no. 5 (March 4, 2022): 2652. http://dx.doi.org/10.3390/app12052652.

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Maintaining rice yield, soil function, and fertility are essential components of long-term compost fertilization. However, paddy fields are major sources of anthropogenic methane emissions. The aim of the study is to evaluate the changes in soil chemical properties and their concurrent impact on the abundance of methanogenesis (mcrA) and methane oxidation (pmoA) related genes among compost (Com), NPK+Compost (NPKCom), and unfertilized (NF) fallow paddy fields under long-term compost fertilization. Results showed that compost and NPK+Compost fertilization altered the soil chemical properties of paddy fields with a significant increase in the functional gene abundance potentially associated with Methanobacteriaceae for mcrA (1.23 × 106 to 3.84 × 106 copy number g−1 dry soil) and methane oxidizing bacteria such as Methylomonas and Methylobacter for pmoA (1.65 × 106 to 4.3 × 106 copy number g−1 dry soil). Ordination plots visualized these changes, where treatments clustered distinctly indicating that Com and NPKCom treatments were characterized by paddy soils with elevated OM, TN, K and P content and higher abundances of methanogenesis and methane oxidation related genes. The study showed that long-term compost fertilization resulted in paddy fields with high nutrient content and high gene abundance, attributed to methanogens and methane oxidizing bacteria that responded well with compost fertilization. These results indicated the potential of these fallow paddy fields for methane emission and methane oxidation and that they are ‘primed’, potentially influencing subsequent paddy field responses to long-term compost application.

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Song, Byeong-Kwan, Hwan-Young Kim, Kun-Su Kim, Jeong-Woo Yang, and Nong-Moon Hwang. "Unusual Dependence of the Diamond Growth Rate on the Methane Concentration in the Hot Filament Chemical Vapor Deposition Process." Materials 14, no. 2 (January 16, 2021): 426. http://dx.doi.org/10.3390/ma14020426.

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Although the growth rate of diamond increased with increasing methane concentration at the filament temperature of 2100 °C during a hot filament chemical vapor deposition (HFCVD), it decreased with increasing methane concentration from 1% CH4 –99% H2 to 3% CH4 –97% H2 at 1900 °C. We investigated this unusual dependence of the growth rate on the methane concentration, which might give insight into the growth mechanism of a diamond. One possibility would be that the high methane concentration increases the non-diamond phase, which is then etched faster by atomic hydrogen, resulting in a decrease in the growth rate with increasing methane concentration. At 3% CH4 –97% H2, the graphite was coated on the hot filament both at 1900 °C and 2100 °C. The graphite coating on the filament decreased the number of electrons emitted from the hot filament. The electron emission at 3% CH4 –97% H2 was 13 times less than that at 1% CH4 –99% H2 at the filament temperature of 1900 °C. The lower number of electrons at 3% CH4 –97% H2 was attributed to the formation of the non-diamond phase, which etched faster than diamond, resulting in a lower growth rate.

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Atkinson, Fiona S., Dale Hancock, Peter Petocz, and Jennie C. Brand-Miller. "The physiologic and phenotypic significance of variation in human amylase gene copy number." American Journal of Clinical Nutrition 108, no. 4 (September 18, 2018): 737–48. http://dx.doi.org/10.1093/ajcn/nqy164.

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Abstract Background Salivary α-amylase gene (AMY1) copy number (CN) correlates with the amount of salivary α-amylase, but beyond this, the physiologic significance is uncertain. Objective We hypothesized that individuals with higher AMY1 CN would digest starchy foods faster and show higher postprandial responses and lower breath hydrogen excretion compared with those with low CN. Design Four linked studies were conducted. In Study 1, we genotyped 201 healthy subjects with the use of real-time quantitative polymerase chain reaction and determined glucose tolerance, insulin sensitivity, salivary α-amylase activity, body mass index (BMI), and macronutrient intake. In Study 2, a pool of 114 subjects tested 6 starchy foods, 3 sugary foods, 1 mixed meal, and 2 reference glucose solutions, containing either 50 or 25 g of available carbohydrate. In Study 3, we compared glycemic and insulin responses to starchy foods with responses to glucose in 40 individuals at extremes of high and low CN. In Study 4, we compared breath hydrogen and methane responses over 8 h in 30 individuals at extremes of CN. Results AMY1 CN correlated positively with salivary α-amylase activity (r = 0.62, P < 0.0001, n = 201) but not with BMI, glucose tolerance, or insulin sensitivity. However, CN was strongly correlated with normalized glycemic responses to all starchy foods (explaining 26–61% of interindividual variation), but not to sucrose or fruit. Individuals in the highest compared with the lowest decile of CN produced modestly higher glycemia (+15%, P = 0.018), but not insulinemia, after consuming 2 starchy foods. Low-CN individuals displayed >6-fold higher breath methane levels in the fasting state and after starch ingestion than high-CN individuals (P = 0.001), whereas hydrogen excretion was similar. Conclusions Starchy foods are digested faster and produce higher postprandial glycemia in individuals with high AMY1 CN. In contrast, having low CN is associated with colonic methane production. This trial was registered at www.anzctr.org.au as ACTRN12617000670370.

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Zhang, Liqiang, Yu Wu, Hai Pu, Xiaoping He, and Pan Li. "The Migration of Coalbed Methane under Mining Pressure and Air Injection: A Case Study in China." Geofluids 2018 (August 5, 2018): 1–14. http://dx.doi.org/10.1155/2018/4034296.

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Gas outburst has always affected the safety of coal mining. To eliminate this risk by high-efficiency extraction of coalbed methane (CBM) in 4102 working face of number 3 coal seam in Hebi Number 3 coal mine, a model of CBM extraction in working face was established which was considering the mining impact of adjacent 4101 working face. In this model, the coupling relationships between stress, desorption, and migration of methane were analyzed. Moreover, we also studied the changes of methane pressure, plastic failure scope, and permeability of coal during the mining and then verified the results with the field data. And on this basis, a stimulation solution for methane extraction by injecting air into coal seam was presented, and the extraction effect was simulated. The simulation results show that the injection of air decreases the effective stress of coal which increases the permeability of coal and promotes the methane migration within the coal seam fractures. Besides, affected by the velocity of gas migration, the pressure drop between fractures and matrix will reduce with time while air injection can provide extra power for gas migration in fractures which causes the desorption and diffusion of methane in the matrix. So this stimulation solution can enhance the efficiency of gas extraction of coal seam and prevent gas outburst of the working face.

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Ouerghi, E., T. Ehret, C. de Franchis, G. Facciolo, T. Lauvaux, E. Meinhardt, and J. M. Morel. "DETECTION OF METHANE PLUMES IN HYPERSPECTRAL IMAGES FROM SENTINEL-5P BY COUPLING ANOMALY DETECTION AND PATTERN RECOGNITION." ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences V-3-2021 (June 17, 2021): 81–87. http://dx.doi.org/10.5194/isprs-annals-v-3-2021-81-2021.

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Abstract. Reducing methane emissions is essential to tackle climate change. Here, we address the problem of detecting large methane leaks using hyperspectral data from the Sentinel-5P satellite. For that we exploit the fine spectral sampling of Sentinel-5P data to detect methane absorption features visible in the shortwave infrared wavelength range (SWIR). Our method involves three separate steps: i) background subtraction, ii) detection of local maxima in the negative logarithmic spectrum of each pixel and iii) anomaly detection in the background-free image. In the first step, we remove the impact of the albedo using albedo maps and the impact of the atmosphere by using a principal component analysis (PCA) over a time series of past observations. In the second step, we count for each pixel the number of local maxima that correspond to a subset of local maxima in the methane absorption spectrum. This counting method allows us to set up a statistical a contrario test that controls the false alarm rate of our detections. In the last step we use an anomaly detector to isolate potential methane plumes and we intersect those potential plumes with what have been detected in the second step. This process strongly reduces the number of false alarms. We validate our method by comparing the detected plumes against a dataset of plumes manually annotated on the Sentinel-5P L2 methane product.

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Koutmos, P. "A Damkohler number description of local extinction in turbulent methane jet diffusion flames." Fuel 78, no. 5 (April 1999): 623–26. http://dx.doi.org/10.1016/s0016-2361(98)00175-6.

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Zhou, Shichen, Bo Zhou, Shifeng Xue, and Peng Jia. "Evolution of Coordination Number of Methane Hydrate Bearing Sediments during Quasi-static Shearing." IOP Conference Series: Earth and Environmental Science 605 (December 1, 2020): 012018. http://dx.doi.org/10.1088/1755-1315/605/1/012018.

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Anderson, Graydon K. "Enthalpy of dissociation and hydration number of methane hydrate from the Clapeyron equation." Journal of Chemical Thermodynamics 36, no. 12 (December 2004): 1119–27. http://dx.doi.org/10.1016/j.jct.2004.07.005.

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Kurtén, T., L. Zhou, R. Makkonen, J. Merikanto, P. Räisänen, M. Boy, N. Richards, et al. "Large methane releases lead to strong aerosol forcing and reduced cloudiness." Atmospheric Chemistry and Physics Discussions 11, no. 3 (March 16, 2011): 9057–81. http://dx.doi.org/10.5194/acpd-11-9057-2011.

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Abstract. The release of vast quantities of methane into the atmosphere as a result of clathrate destabilization is a potential mechanism for rapid amplification of global warming. Previous studies have calculated the enhanced warming based mainly on the radiative effect of the methane itself, with smaller contributions from the associated carbon dioxide or ozone increases. Here, we study the effect of strongly elevated methane (CH4) levels on oxidant and aerosol particle concentrations using a combination of chemistry-transport and general circulation models. A 10-fold increase in methane concentrations is predicted to significantly decrease hydroxyl radical (OH) concentrations, while moderately increasing ozone (O3). These changes lead to a 70% increase in the atmospheric lifetime of methane, and an 18% decrease in global mean cloud droplet number concentrations (CDNC). The CDNC change causes a radiative forcing that is comparable in magnitude to the longwave radiative forcing ("enhanced greenhouse effect") of the added methane. Together, the indirect CH4-O3 and CH4-OH-aerosol forcings could more than double the warming effect of large methane increases. Our findings may help explain the anomalously large temperature changes associated with historic methane releases.

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Kurtén, T., L. Zhou, R. Makkonen, J. Merikanto, P. Räisänen, M. Boy, N. Richards, et al. "Large methane releases lead to strong aerosol forcing and reduced cloudiness." Atmospheric Chemistry and Physics 11, no. 14 (July 18, 2011): 6961–69. http://dx.doi.org/10.5194/acp-11-6961-2011.

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Abstract. The release of vast quantities of methane into the atmosphere as a result of clathrate destabilization is a potential mechanism for rapid amplification of global warming. Previous studies have calculated the enhanced warming based mainly on the radiative effect of the methane itself, with smaller contributions from the associated carbon dioxide or ozone increases. Here, we study the effect of strongly elevated methane (CH4) levels on oxidant and aerosol particle concentrations using a combination of chemistry-transport and general circulation models. A 10-fold increase in methane concentrations is predicted to significantly decrease hydroxyl radical (OH) concentrations, while moderately increasing ozone (O3). These changes lead to a 70 % increase in the atmospheric lifetime of methane, and an 18 % decrease in global mean cloud droplet number concentrations (CDNC). The CDNC change causes a radiative forcing that is comparable in magnitude to the longwave radiative forcing ("enhanced greenhouse effect") of the added methane. Together, the indirect CH4-O3 and CH4-OH-aerosol forcings could more than double the warming effect of large methane increases. Our findings may help explain the anomalously large temperature changes associated with historic methane releases.

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MUTTAQIN, MAFRIKHUL, MIFTAHUDIN ., and IMAN RUSMANA. "Bacteria as Greenhouse Gases Reducing Agents from Paddy Plantation." Jurnal Sumberdaya Hayati 2, no. 2 (March 2, 2017): 45–51. http://dx.doi.org/10.29244/jsdh.2.2.45-51.

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Abstract:

High methane oxidation activity of local isolated methanotrophic bacteria have a potent as methane gases reducing agent while combined with nitrogen fixing bacteria as paddy biofertilizer. The aim of the research was to evaluate the effectiveness of the bacteria as methane gases reducing agent and biofertilizer in paddy plantation. The research was arranged in a completely randomized design consisted of fertilizer types and watering system treatments with four replicates. The research showed that paddy shoot length was not affected by the treatment. On the other hand, both plant freshand dry weight, as well as the number of productive tiller were affected by interaction of fertilizer types and watering system. Fertilizer types affected grain per panicle and methane flux after fertilization. In the end of paddy vegetative stage, bacterial fertilizers were capable to reduce methane emission in different rate. The different result in methane flux was likely due to the interaction between soil local microorganisms and soil chemical component.

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Journal articles on the topic 'Methane number'

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