Liquids flow, release models

Understanding of gas-liquid flow in electrochemical systems is very important for system optimization, enhance mass transport and thus gas release efficiency. There are relatively little theoretical studies available in the literature which considers process as a two-phase flow problem. Zeigler and Evans[2] applied the drift - flux model of Ishii[3] to electrochemical cell and obtained velocity field, bubble distribution, mass transfer rate. Instead of treating the bubbles as a second phase, they obtained bubble distribution from concentration equation. Dahikild [4] developed an extensive mathematical model for gas evolving electrochemical cells and performed a boundary layer analysis near a vertical electrode. 

Transport Model. A general release equation is developed by considering diffusion in both the liquid and gaseous phases. Figure 1 is a sketch of a vessel containing liquid sodium, blanketed by a flowing inert gas and maintained at constant temperature. The assumed cesium concentration profiles for both phases are shown in the sketch. Fick s law of diffusion may be applied to the liquid phase ... 

Comparison of Release Data with Proposed Model. A summary of the cesium release data obtained with helium as carrier gas is shown in Figure 5, where the percentage of cesium remaining is plotted vs, heating time on semilogarithmic coordinates. In all of the experiments the flow rate was maintained at 300 cc./min. and the temperature at 730° = = 5°K. The geometric parameters are indicated on each curve. Since only about 5% of the sodium was vaporized in each experiment, the assumption of a stationary liquid-phase boundary is justified. 

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