04/01751 Effect of coal char size and reaction gas flow speed on the coal char-carbon dioxide reaction

Abstract The gas flow of carbon dioxide from the catalyst layer (CL) through the microporous layer (MPL) and gas diffusion layer (GDL) has great impacts on the water and fuel management in direct methanol fuel cells (DMFCs). This work has developed a liquid–vapor two-phase model considering the counter flow of carbon dioxide gas, methanol, and water liquid solution in porous electrodes of DMFC. The model simulation includes the capillary pressure as well as the pressure drop due to flow resistance through the fuel cell components. The pressure drop of carbon dioxide flow is found to be about two to three orders of magnitude higher than the pressure drop of the liquid flow. The big difference between liquid and gas pressure drops can be explained by two reasons: volume flowrate of gas is three orders of magnitude higher than that of liquid; only a small fraction of pores (<5%) in hydrophilic fuel cell components are available for gas flow. Model results indicate that the gas pressure and the mass transfer resistance of liquid and gas are more sensitive to the pore size distribution than the thickness of porous components. To buildup high gas pressure and high mass transfer resistance of liquid, the MPL and CL should avoid micro-cracks during manufacture. Distributions of pore size and wettability of the GDL and MPL have been designed to reduce the methanol crossover and improve fuel efficiency. The model results provide design guidance to obtain superior DMFC performance using highly concentrated methanol solutions or even pure methanol.

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High Flue Gas Flow Rate Tests for Removal and Recovery of Carbon Dioxide under Power Plant Effluent Gas Conditions

KAGAKU KOGAKU RONBUNSHU ◽

10.1252/kakoronbunshu.30.758 ◽

2004 ◽

Vol 30 (6) ◽

pp. 758-761

Author(s):

Tomio MIMURA ◽

Yasuyuki YAGI ◽

Masaki IIJIMA ◽

Ryuji YOSIYAMA ◽

Takahito YONEKAWA

Keyword(s):

Carbon Dioxide ◽

Power Plant ◽

Flow Rate ◽

Flue Gas ◽

Gas Flow ◽

Gas Flow Rate ◽

Power Plant Effluent ◽

Removal And Recovery

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A new real-time and precision capnography for human respiration carbon dioxide concentration

Perfusion ◽

10.1177/0267659110380772 ◽

2010 ◽

Vol 25 (6) ◽

pp. 399-408 ◽

Cited By ~ 3

Author(s):

Jiachen Yang ◽

Bin Wang ◽

Ran Xu ◽

Lei Wang

Keyword(s):

Carbon Dioxide ◽

Real Time ◽

Gas Flow ◽

Measurement Accuracy ◽

Carbon Dioxide Concentration ◽

Main Stream ◽

Temperature Drift ◽

New Device ◽

Human Respiration ◽

Gas Measurement

This paper is a description of the designing of a new mainstream device to measure human respiration carbon dioxide concentration, based on non-dispersive infrared (NDIR) absorption technology. The device can be used to accurately monitor the cardiopulmonary status during anaesthesia and mechanical ventilation in real time. This new device can not only make up the error of real-time gas measurement of the side-stream device, but also make up the accuracy of the main-stream device. In the paper, four issues which can affect the measurement accuracy were considered: respiration gas flow, turbulence of the light source with all ranges of wavelength, temperature drift and signal noise. The experimental results showed that the device could produce a stable output signal and deviation of measurement accuracy could be achieved to within 4%.

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COMPARATIVE CALCULATIONS OF HYDRODYNAMIC AND STRUCTURAL PARAMETERS OF THE ABSORBER TO IMPROVE THE EFFICIENCY OF TREATMENT OF INDUSTRIAL WATERS OF ENTERPRISES

Известия вузов. Пищевая технология ◽

10.26297/0579-3009.2020.1.22 ◽

2020 ◽

Author(s):

Е.Г. СТЕПАНОВА ◽

Н.А. ПУХАЧЕВ ◽

Б.Ю. ОРЛОВ ◽

М.А. ПЕЧЕРИЦА

Keyword(s):

Waste Water ◽

Carbon Dioxide ◽

Gas Flow ◽

Structural Parameters ◽

Active Surface ◽

Column Diameter ◽

Gas Flow Rate ◽

Maximum Value ◽

Water Pretreatment ◽

Production Water

Проведены сравнительные гидродинамические и конструктивные расчеты процесса абсорбции углекислого газа и аммиака из отработанных производственных вод пищевых предприятий в аппаратах с деревянными хордовыми насадками, с насадками в виде керамических колец Палля и в адсорбере с хордовыми насадками с предварительной обработкой воды в диафрагменном электролизере. Расчеты выполнены с помощью пакета Mathcad 13. Установлено, что максимальное значение объемной интенсивности при расходе газа 13,9 м3/с и плотности орошения 9,7 Ч 104 м3/(м2 Ч с) получено в адсорбере с хордовыми насадками при предварительной обработке воды в диафрагменном электролизере. Оптимальные размеры колонны адсорбера: диаметр 1,8 м, доля активной поверхности насадки 0,914. Предварительная электрообработка воды перед абсорбцией значительно повышает эффективность очистки, что позволяет очищенную от газовых примесей производственную воду повторно использовать на технологические нужды пищевых предприятий. Comparative hydrodynamic and structural calculations of the process of absorption of carbon dioxide and ammonia from waste water of food enterprises in devices with wooden chord nozzles, with nozzles in the form of ceramic Pall rings and in an adsorber with chord nozzles with pretreatment of water in a diaphragm electrolyzer were carried out. The calculations are performed using the Mathcad 13 package. It was found that the maximum value of the volumetric intensity at a gas flow rate of 13,9 m3/sec and the irrigation density of 9,7 Ч 104 m3/(m2 Ч sec) was obtained in an adsorber with chord nozzles during pretreatment of water pretreatment of water in a diaphragm electrolyzer. Optimal dimensions of the adsorber column: diameter 1,8 m, the proportion of the active surface of the nozzle 0,914. Preliminary electrical treatment of water before absorption significantly increases the efficiency of purification, which allows purified from gas impurities production water to be reused for the technological needs of food enterprises.

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Effects of Shield Gas Flow on Meltpool Variability and Signature in Scanned Laser Melting

Volume 1: Additive Manufacturing; Advanced Materials Manufacturing; Biomanufacturing; Life Cycle Engineering; Manufacturing Equipment and Automation ◽

10.1115/msec2020-8410 ◽

2020 ◽

Author(s):

David C. Deisenroth ◽

Jorge Neira ◽

Jordan Weaver ◽

Ho Yeung

Keyword(s):

Additive Manufacturing ◽

Aspect Ratio ◽

Flow Velocity ◽

Process Monitoring ◽

Gas Flow ◽

Laser Energy ◽

Flow Speed ◽

Powder Bed ◽

Flow Speeds ◽

Gas Flow Velocity

Abstract In laser powder bed fusion metal additive manufacturing, insufficient shield gas flow allows accumulation of condensate and ejecta above the build plane and in the beam path. These process byproducts are associated with beam obstruction, attenuation, and thermal lensing, which then lead to lack of fusion and other defects. Furthermore, lack of gas flow can allow excessive amounts of ejecta to redeposit onto the build surface or powder bed, causing further part defects. The current investigation was a preliminary study on how gas flow velocity and direction affect laser delivery to a bare substrate of Nickel Alloy 625 (IN625) in the National Institute of Standards and Technology (NIST) Additive Manufacturing Metrology Testbed (AMMT). Melt tracks were formed under several gas flow speeds, gas flow directions, and energy densities. The tracks were then cross-sectioned and measured. The melt track aspect ratio and aspect ratio coefficient of variation (CV) were reported as a function of gas flow speed and direction. It was found that a mean gas flow velocity of 6.7 m/s from a nozzle 6.35 mm in diameter was sufficient to reduce meltpool aspect ratio CV to less than 15 %. Real-time inline hotspot area and its CV were evaluated as a process monitoring signature for identifying poor laser delivery due to inadequate gas flow. It was found that inline hotspot size could be used to distinguish between conduction mode and transition mode processes, but became diminishingly sensitive as applied laser energy density increased toward keyhole mode. Increased hotspot size CV (associated with inadequate gas flow) was associated with an increased meltpool aspect ratio CV. Finally, it was found that use of the inline hotspot CV showed a bias toward higher CV values when the laser was scanned nominally toward the gas flow, which indicates that this bias must be considered in order to use hotspot area CV as a process monitoring signature. This study concludes that gas flow speed and direction have important ramifications for both laser delivery and process monitoring.

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Environmental and economic impact of using increased fresh gas flow to reduce carbon dioxide absorbent consumption in the absence of inhalational anaesthetics

British Journal of Anaesthesia ◽

10.1016/j.bja.2020.07.043 ◽

2020 ◽

Vol 125 (5) ◽

pp. 773-778 ◽

Cited By ~ 2

Author(s):

George Zhong ◽

Ali Abbas ◽

Joseph Jones ◽

Sarah Kong ◽

Tim McCulloch

Keyword(s):

Carbon Dioxide ◽

Economic Impact ◽

Gas Flow ◽

Reduce Carbon Dioxide ◽

Carbon Dioxide Absorbent

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Biological treatment characteristics of benzene and toluene in a biofilter packed with cylindrical activated carbon

Water Science & Technology ◽

10.2166/wst.2002.0716 ◽

2002 ◽

Vol 46 (11-12) ◽

pp. 51-56 ◽

Cited By ~ 3

Author(s):

G.-W. Li ◽

H.-Y. Hu ◽

J.-M. Hao ◽

H.-Q. Zhang

Keyword(s):

Carbon Dioxide ◽

Activated Carbon ◽

Gas Flow ◽

Removal Rate ◽

Carbon Dioxide Concentration ◽

Organic Load ◽

Filler Materials ◽

Removal Capacity ◽

Bacillus Spore ◽

Maximum Removal

The biodegradation of toluene and benzene in a biofilter using cylindrical activated carbon as the filler materials was studied. Three gas flow rates, i.e. 0.25, 0.50 and 0.75 m3/h, corresponding to empty bed gas residence of 75, 37.5 and 25 s, respectively, and total organic load lower than 400 g/m3.h were tested. The biofilter proved to be highly efficient in biodegradation of toluene and benzene, and toluene was more easily degraded than benzene. When each inlet load was lower than 150 g/m3.h, removal rate increased with inlet load and reached a maximum, which was 150 and 120 g/m−3.h for toluene and benzene, respectively. For inlet load higher than the maximum removal capacity conditions, the removal rate decreased with inlet load. Carbon dioxide concentration profile through the biofilter revealed that the mass ratios of carbon dioxide produced to the toluene and benzene removed were 2.15 g(CO2)/g(toluene) and 1.67 g(CO2)/g(benzene), which furthermore, confirmed the biodegradation performance in biofilter. The observation of biotic community demonstrated that the microbes consisted of bacillus, spore bacillus and fungi, of which the spore bacillus was dominant.

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