Gas-film mass transfer coefficient

Molstad, M. C., McKinney, J. F. and Abbey, R. G. Trans. Am. Inst. Chem. Eng. 39 (1943) 605. Performance of drip-point grid tower packings, III. Gas-film mass transfer coefficients additional liquid-film mass transfer coefficients. 

As stated in Section 2.6, two kinds of gas film mass transfer coefficients - Icq, based on the partial pressure driving potential, and based on the concentration driving potential - can be defined. However, hereafter in this text only the latter type is used in other words. 

As mentioned, from the point of view of practical application, impinging streams is not suitable for the systems given in Table 7.2. On the other hand, the absorption processes for which impinging streams is applicable normally involve fast reaction(s) in liquid and thus are controlled by gas-film diffusion. Therefore the most important should be the gas-film mass transfer coefficient, kti, which is absent in the table. 

Figure 7.16 Influence of S02 concentration in feed gas on gas-film mass transfer coefficient. (The experimental conditions are the same as for Fig. 7.15).

Using the model equations described above and from the experimental data yielding Fig. 7.13, the calculated data are given in Fig. 7.18 as the plot of kG versus nn. By regression, the experimental data are fitted to represent the relationship between gas-film mass transfer coefficient and impinging velocity by... 

The gas-film mass transfer coefficient, kG, was determined based on the Sauter mean diameter of spray droplets. The results show essentially no influence of initial concentration of SOz on kG, suggesting that the process is controlled by diffusion through gas film and that the method proposed for the determination of kG is feasible ... 

The data on the relationship between impinging velocity and gas-film mass transfer coefficient were fitted by kG = 2.9 xlO 4no75821, with the standard deviation SD = 2.45X10 4 m-s 1, implying u0 is a strong effecting variable, and thus a very important operation variable ... 

Doan, H.D. Fayed, M.E. Entrance effect and gas-film mass-transfer coefficient in a large-diameter packed column. Ind. Eng. Chem. Res. 2000, 39 (4), 1039-1047. 

Kg = Overall gas film mass transfer coefficient, gmol/... 

The gas-film mass transfer coefficient to a drop can be estimated on the basis of the following semiem-pineal equation ... 

With the assumption that the properties of the gas mixture are the same as those of air, calculate the gas-film mass-transfer coefficient using equation (2-90) and compare the result with the value reported by Wilke and Hougan. 

In many cases of gas-liquid reactions the gaseous component is transferred into the liquid phase from a pure gas phase. There is no gas-side resistance to mass transfer and equations (7-110) and (7-111) express the overall gas-liquid reaction enhancement. If we wish to include gas-phase resistance, however, a simple modification is possible. Here we will designate Pas and Paj as the partial pressures of the transferred component in the bulk gas and at the interface, respectively, kQ is the gas film mass-transfer coefficient, and H is Henry s law constant pertaining to equilibrium at the interface. Then, the overall flux relationship may be derived as... 

---