中空糸気液接触器における二酸化炭素移動速度の解析

1. Physico-Chemical Fundamentals.- Physical-chemical phenomena and molecular properties.- The determination of Henry's Constant for volatile organics by equilibrium partitioning in closed systems.- Volatilization of chlorinated hydrocarbons from water.- The ratio of gas-phase to liquid-phase mass transfer coefficients in gas-liquid contacting processes.- Absorption of gases at condensing and evaporating water surfaces.- The effects of evaporation and condensation on an absorption process.- 2. Turbulence near Gas-Liquid Interfaces.- Turbulence structure and turbulent diffusion near gas-liquid interfaces.- Turbulence measurements near the free surface in stirred grid experiments.- A laboratory technique for investigating the relationship between gas transfer and fluid turbulence.- Carbon dioxide transfer at the gas/water interface as a function of system turbulence.- Turbulence structure of wavy stratified air-water flow.- Current fluctuations in the surface waters of small lakes.- Moisture and heat transport in a stably stratified boundary layer over a water surface.- 3. Interfacial Motions and Instabilities.- Wind-wave effects on gas transfer.- Interfacial motion observed during experiments on air-water gas transfer.- A laboratory study of the velocity field below surface gravity waves.- The roles of Langmuir circulations in gas transfer across natural water surfaces.- Measurements of the fluctuating pressure in the turbulent boundary layer over progressive, mechanically generated water waves.- Experimental studies of surface wave breaking and air entrainment.- Bubbles produced by breaking wind waves.- The role of bubbles for gas transfer from water to air at higher windspeeds. Experiments in the wind-wave facility in Hamburg.- A new optical bubble measuring device A simple model for bubble contribution to gas exchange.- Contribution of bubbles to gas transfer across an air-water interface.- Entrapment and transport of bubbles by plunging water.- 4. Conceptual Models and Parameterizations of Gas Transfer.- Conceptual models of gas exchange.- A comparison of turbulent mass transfer at gas-liquid and solid-liquid interfaces.- The variation of the gas transfer coefficient with molecular diffusity.- Wind/wave-tunnel experiment on the Schmidt number - and wave field dependence of air/water exchange.- A model of interfacial gas transfer for a well-roughened sea.- Turbulent transfer across smooth and rough surfaces.- Reaeration of open channel flow.- Dependence of oxygen transfer rate on energy dissipation during surface aeration and in stream flow.- Wind effects on air-water oxygen transfer in a lake.- Reaeration and wind induced turbulence shear in a contained water body.- 5. Field and Laboratory Experimental Techniques.- Field techniques for reaeration measurements in rivers.- Gas transfer rate coefficient measurement of wastewater aeration equipment by a stable isotope krypton/lithium technique.- Reaeration studies on some New Zealand rivers using methyl chloride as a gas tracer.- Dichlorodifluoromethane (Freon-12) as a tracer for nitrous oxide release from a nitrogen-enriched river.- An assessment of the radiotracer technique for measuring reaeration rates in large river systems.- Measurements of wind effects on water-side controlled gas exchange in riverine systems.- Optimum application of the radon deficit method to obtain air-sea gas exchange rates.- Parametrization of air/lake gas exchange.- Simultaneous in situ determination of dissolved gases by gas chromatography.- 6. Climate and Oceanographic Applications.- Gas exchange measurements in natural systems.- The role of oceanic whitecaps in air-sea gas exchange.- On the exchange of oxygen and carbon dioxide between ocean and atmosphere in an eastern boundary current.- Invasion of fossil fuel CO2 into the ocean.- In situ pH measurements as an indicator of CO2 gas transfer in glacial meltwaters.- The transfer of mercury at the air/water interface.- Exchange rates of dimethyl sulfide between ocean and atmosphere.- Laboratory observations on transfer of atmospheric oxygen into stratified seawater.- 7. Water Quality and Engineering Applications.- The significance of gas exchange in water quality assessment and planning.- The sensitivity of the dissolved oxygen balance to predictive reaeration equations.- Estimation of volatilization of toxics for multimedia modeling.- Reaeration measurement in swamp streams: Radiotracer case studies.- Prediction of dissolved gas transfer in spillway and outlet works stilling basin flows.- Carbon dioxide desorption from the activated sludge at the waste water treatment plants.- Volatilization of fission products in nuclear reactor buildings.- Self-propelled weir aerators.

Modelling hollow fiber membrane modules for anesthesia gas separation

Gas–liquid mass transfer phenomena in bio-oxidation experiments of sulphide minerals: A critical review of literature data

Surface-renewal motions in the interfacial region below a gas-liquid interface were experimentally investigated in relation to bursting motions in the wall region. To estimate the frequency of the appearance of surface-renewal eddies, mass-transport experiments with methylene-blue solution, together with velocity measurements, were done in an open-channel flow. The instantaneous concentration of methylene-blue tracer emitted from a point source positioned in the buffer layer was measured at the free surface downstream from the source by an optical probe. Instantaneous streamwise velocity was measured using a laser-Doppler velocimeter at a position in the buffer region. Frequencies of both surface-renewal and bursting events were computed from these concentration and velocity signals using a conditional-averaging method. In order to clarify whether the surface-renewal eddies actually dominate mass transfer across the gas-liquid interface, gas-absorption experiments were added. Carbon dioxide was absorbed into the water flow across the calm free surface and its mass-transfer coefficient on the liquid side was measured under the same flow conditions as used in the above mass-transport experiments. The results show that the surface-renewal motions originate in the bursting motions which vigorously occur in the buffer region. That is, the decelerated fluid which is strongly lifted towards the outer layer by bursting almost always arrives at the free surface and renews the free surface. The frequency of the surface renewal, as well as the bursting frequency, is uniquely determined by the wall variables or the outer-flow variables and the Reynolds number. Mass transfer across the gas-liquid interface is dominated by the large-scale surface-renewal eddies, and the mass-transfer coefficient on the liquid side is proportional to the square-root of the surface-renewal frequency.

Comparative performance of non-dispersive solvent extraction using a single module and the integrated membrane process with two hollow fiber contactors

To investigate the factors influencing carbon dioxide transfer in a system that integrates an oxygenation membrane in series with high-bicarbonate continuous veno-venous hemodialysis in hypercapnic animals. In an experimental setting, we induced severe acute kidney injury and hypercapnia in five female Landrace pigs. Subsequently, we initiated high (40mEq/L) bicarbonate continuous veno-venous hemodialysis with an oxygenation membrane in series to maintain a pH above 7.25. At intervals of 1 hour, 6 hours, and 12 hours following the initiation of continuous veno-venous hemodialysis, we performed standardized sweep gas flow titration to quantify carbon dioxide transfer. We evaluated factors associated with carbon dioxide transfer through the membrane lung with a mixed linear model. A total of 20 sweep gas flow titration procedures were conducted, yielding 84 measurements of carbon dioxide transfer. Multivariate analysis revealed associations among the following (coefficients ± standard errors): core temperature (+7.8 ± 1.6 °C, p < 0.001), premembrane partial pressure of carbon dioxide (+0.2 ± 0.1/mmHg, p < 0.001), hemoglobin level (+3.5 ± 0.6/g/dL, p < 0.001), sweep gas flow (+6.2 ± 0.2/L/minute, p < 0.001), and arterial oxygen saturation (-0.5 ± 0.2%, p = 0.019). Among these variables, and within the physiological ranges evaluated, sweep gas flow was the primary modifiable factor influencing the efficacy of low-blood-flow carbon dioxide removal. Sweep gas flow is the main carbon dioxide removal-related variable during continuous veno-venous hemodialysis with a high bicarbonate level coupled with an oxygenator. Other carbon dioxide transfer modulating variables included the hemoglobin level, arterial oxygen saturation, partial pressure of carbon dioxide and core temperature. These results should be interpreted as exploratory to inform other well-designed experimental or clinical studies.

Modeling carbon dioxide, pH, and un-ionized ammonia relationships in serial reuse systems

Cellulose acetate nanofiltration hollow fiber membranes for forward osmosis processes

RESEARCH and concepts related to the response of crops to limited oxygen and carbon dioxide transfer in the soil profile, produced by excess soil water conditions, and the mechanisms for gaseous transfer are reviewed and evaluated. The conceptual framework for a physically-based model capable of defining the dynamic status of water, air, oxygen, and carbon dioxide in the root zone is proposed

High‐flow nasal therapy – modelling the mechanism

Hollow fiber polytetrafluoroethylene membrane heat exchanger with anti-corrosion properties

This study was carried out to examine the apparatus in measuring the photosynthetic activity of vegetable plants and to discuss some problems in relation to the methods of measurement and plant materials.Whole plant or single attached leaf was placed in the“Plexiglass”assimilation chamber in which the light intensity, the carbon dioxide concentration, the leaf temperature and the air humidity could be controlled over a wide range. The carbon dioxide concentration in the air of the inlet and outlet of the chamber was measured with infrared gas analyser, Hitachi-Horiba Type EIA-1 A (0-600ppm, 0-2, 000ppm).In order to reduce the resistance against carbon dioxide transfer at boundary layer of leaf surface, an air circulating fan was installed in the plant assimilation chamber. The leaf assimilation chamber was also well constructed to distribute the air uniformly over entire leaf surface.Photosynthetic activity of the tomato plant in the assimilation chamber increased with increased air supply up to the order of 0.8l/cm2 leaf area/hr. Without operating air circulating fan, however, air supply of 2.0l/cm2/hr was not enough for adequate photosynthesis in the plant. This would suggest that the resistance of boundary layer of leaf surface against carbon dioxide transfer was one of the serious problems to achieve the sufficient photosynthesis in the assimilation chamber.As the gas analyser used in this study has maximum error of 1 per cent of the carbon dioxide concentration over a given range, it is of considerable importance to define the lowest limit of air supply. In this apparatus the photosynthetic activity should be measured with the air supply of approximately 1.0l/cm2/hr and with carbon dioxide depletion of not more than 20 per cent of inlet air.The photosynthetic activity of the tomato plant was almost independent of the leaf temperature at a normal carbon dioxide supply. However, in the atmosphere enriched with carbon dioxide, the rate of photosynthesis was greatly influenced by the leaf temperature within the range of 15°C to 35°C.Considerably large standard deviation of photosynthetic activity was found in the tomato plants which were placed under natural conditions and sampled immediately before the measurement. Therefore, the plant materials should be selected in the evening and kept under controlled conditions for certain hours in the dark so as not to disturb the internal equilibrium.When the photosynthetic rate was measured in a single cucumber leaf, the rate was slightly increased by darkening of young leaves outside assimilation chamber. By lowering the root temperature from 18°C to 13°C, the photosynthetic rate in the leaf dropped to 76 per cent of the normal. The steady state of the photosynthesis under given conditions was obtained after about 50 minutes of the exposure to the light. So it is suggested that the leaves outside assimilation chamber and root should be kept under the controlled conditions during the measurement of photosynthesis.

In relation to global warming and the role of carbon dioxide, the atmospheric residence-time of carbon dioxide from industrial emissions, and the carbon dioxide fixation capacity by photosynthesis in forests, land areas and oceans is considered, for the decades 1960 to 2010. Carbon dioxide fixation in forests, annually and worldwide, is estimated to be larger than the annual and global carbon dioxide emissions from industrial and land use activities, for the decades 1960 to 2010. Observations of the Keeling curve for the period 1960 to 2010, imply slow and rate-limiting steps for the atmospheric carbon dioxide cycle from industrial emissions, namely the transfer of carbon dioxide from the atmosphere to the Earth’s surface, forests, land areas and oceans. It is proposed that these carbon dioxide emissions have a long residence-time with significant accumulation in the atmosphere. Carbon dioxide emissions from natural-biological sources, namely respiration of organisms and passive emissions from the land and oceans, remain close to the Earth’s surface, with short atmospheric residence-times, rapid conversion into biomass and no significant accumulation in the atmosphere. This is known as the natural carbon dioxide cycle. Research and development are proposed as follows; (a) determination of the atmospheric residence times of industrial, urban and natural carbon dioxide emissions, (b) effective cooling of flue gases from industrial emissions to direct these emissions to lower atmospheric altitude(s), and thereby decrease the atmospheric residence-time(s) of carbon dioxide and (c) synthetic hydrocarbon fuels for aircraft, which are low-carbon in the complete cycle, developed with public-funded research. Global, public-funded research and development programs are proposed for achieving these goals, involving national and international organisations and industries.

The bioleaching of manganese present in mining waste after metal extraction can be catalyzed by Leptospirillum (L.) ferriphilum by allowing atmospheric carbon dioxide to be used in this autotrophic process and generating the subsequent recovery of silver. Bioleaching of metals is widely performed in agitated tanks; therefore, it is important to assess the mass transfer capacity of gaseous substrates, such as carbon dioxide, during the microbial processes. The main objective of this research was to evaluate the effects of the presence and concentration of a transfer vector (silicone oil) added into a stirred-tank bioreactor during bioleaching of mining tailings catalyzed by L. ferriphilum, determined by the combined gas/oil mass transfer coefficient of carbon dioxide (kLaCO2) into the aqueous phase. The experiments were carried out following a Box–Behnken experimental design, evaluating the concentrations of mining waste (30%, 40%, and 50%), Fe2+, serving as electron donor (2, 8, and 14 g/L), and silicon oil (0%, 5%, and 10%). A significant increase in kLaCO2 was observed after the addition of the transfer vector by comparing the lowest kLaCO2 value of 1.68 h−1 (obtained at 50% pulp, 8 g/L Fe2+, and 0% silicone oil) and the highest kLaCO2 of 21.81 h−1 (obtained at 30% pulp, 2 g/L Fe2+, 5% silicone oil). The results showed statistically significant differences in the transfer of carbon dioxide during the bioleaching process with a transfer vector.

The process of absorbing carbon dioxide with an aqueous solution of hot potassium carbonate is widely used in industry for gas purification. The results of numerical modelling of the process are compared with a limited set of experimental data in well-known works. In this paper, a mathematical model of the process in a packed absorber is developed; fitting parameters are taken on the basis of processing known experimental data. The model is based on the equations of heat and mass transfer. Main characteristics: concentrations of substances and temperatures in the liquid and gas phases, depend on one coordinate z directed along the height of the absorber. The heat and mass transfer coefficients were calculated using the Onda formulas. The CO2 equilibrium at the liquid-gas interface was determined by Sechenov relation. The adequacy of the model was checked by comparing the calculations of carbon dioxide concentration along the absorber with the known experimental data not included in the sample from which the model parameters were determined. The numerical dependences of the CO2 content in the scrubbed gas on the physical characteristics of the process are obtained.