Measurement of flooding

H. Yamada, T. Hatanaka, H. Murata, and Y. Morimoto. Measurement of flooding in gas diffusion layers of polymer electrolyte fuel cells with conventional flow field. Journal of the Electrochemical Society 153 (2006) A1748-A1754. 

The design of a multi-purpose plant for the continuous extraction of liquids with supercritical fluids is presented. To provide flexibility in order to treat different feedstocks, a modular concept was developed based on experience gained in the operation of bench-scale and pilot plants. Four test systems were chosen in order to determine the proper dimensions for the equipment. Based on experimental data, e.g. measurements of flooding points and maximum flows for various column internals, the design pressure and temperature and heat exchange requirements were determined. The plant was built by a German manufacturer and was operated successfully by a Canadian company in Edmonton, Alberta. 

Flooding and Pseudo-First-Order Conditions For an example, consider a reaction that is independent of product concentrations and has three reagents. If a large excess of [BJ and [CJ are used, and the disappearance of a lesser amount of A is measured, such flooding of the system with all components butM permits the rate law to be integrated with the assumption that all concentrations are constant except A. Consequentiy, simple expressions are derived for the time variation of A. Under flooding conditions and using equation 8, if x happens to be 1, the time-dependent concentration... 

For column analysis and troubleshooting it is important to have pressure drop measured with a DP cell. The differential pressure can also be used to control column traffic. A good way to do this would be to let the differential pressure control the heating medium to the reboiler. The largest application for differential pressure control is with packed columns where it is desirable to run at 80 to 100% of flood for best efficiency. 

Tower Operations. The tower operator can quickly determine which type of flooding will tend to be the limiting one for a particular system. If a rigorous computer run is available for the anticipated or actual operation, the operator can quickly calculate the expected limiting column section. The operator can then provide DP cell recording for the entire column and limiting section(s). As mentioned previously, a DP cell is the best measure of internal traffic and flooding tendency. 

Experimental flooding and entrainment data for sieve trays are not plentiful, and measurements are not precise. Accordingly, it has been necessary to relate correlations of flooding and entrainment to those of the well-knowm device, the bubble-cap tray. It appears that the two devices have about the same flooding limits, so long as usual design practice is followed. However, the sieve tray shows entrainment advantages, especially when used in vticuum and atmospheric service. 

The Lux-Flood theory relates to oxide melts. Geologists have often used acid-base concepts for the empirical classification of igneous silicate rocks (Read, 1948). Silica is implicitly assumed to be responsible for acidity, and the silica content of a rock is used as a measure of its acid-base balance ... 

In an earlier study calorimetry achieved this objective for the compositional boundaries between two and three phases (2). Such boundaries are encountered both in "middle-phase microemulsion systems" of low tension flooding, and as the "gas, oil, and water" of multi-contact miscible EOR systems (LZ). The three-phase problem presents by far the most severe experimental and interpretational difficulties. Hence, the earlier results have encouraged us to continue the development of calorimetry for the measurement of phase compositions and excess enthalpies of conjugate phases in amphiphilic EOR systems. 

Bronson KF, Neue HU, Singh U, Abao EB. Automated chamber measurements of methane and nitrous oxide flux in a flooded rice soil Residue, nitrogen, and water management. Soil Sci. Soc. Am. J. 1997 61 981—987. 

Surface wave, 17 422. See also S-wave Surfactant adsorption, 24 119, 133-144 at the air/liquid and liquid/liquid interfaces, 24 133-138 approaches for treating, 24 134 measurement of, 24 139 at the solid/liquid interface, 24 138-144 Surfactant blends, in oil displacement efficiency, 13 628-629 Surfactant-defoamers surface tension, <5 244t Surfactant-enhanced alkaline flooding,... 

K. Ito, K. Ashikaga, H. Masuda, et al. Estimation of flooding in PEMFC gas diffusion layer by differential pressure measurement. Journal of Power Sources 175 (2008) 732-738. 

These general features of NOs reduction in submerged rice soils are bom out by field observations. Buresh et al. (1993b) found that from 60 to 75 % of N-labelled NOs" applied on the surface of flooded ricefields was lost by denitrification over 2-3 weeks, as measured by the not recovered in the soil, floodwater and plants. The recovery of (N2 + N20)- N in chambers placed over the floodwater was less than the estimated denitrification loss because gas bubbles became entrapped in the soil. More N2 + N2O was recovered when the chambers were placed over the rice plants showing that some of the gas escaped through the plants. The not lost by denitrification was presumed to have... 

Figure 6.8 The time-course of (a) N uptake, (b) soil solution NH4, and (c) and (d) root length density in pots of flooded soil planted with rice with (O) and without ( ) added N. In (a), lines are fitted logistic curves, slopes of which give values of dU/dt in Equation (6.10). In (b), solid horizontal lines are Cl broken lines Cls calculated with Equation (6.11). In (c) and (d), the lines indicate the minimum root length densities required to explain uptake calculated with the measured Cl values se (full lines) and Cl derived from exchangeable NH4+ values se (Kirk and Solivas, 1997). Reproduced by permission of Blackwell Publishing...

Buresh RJ, Austin ER. 1988. Direct measurement of dinitrogen and nitrous oxide flux in flooded rice fields. Soil Science Society of America Journal 52 681-688. 

To avoid cathode flooding, a hydrophobic cathode backing and an efficient means to remove water droplets in the cathode flow field are required. We report here measurements of water flux in both liquid and vapor forms in the cathode... 

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