Drop formation mass transfer

Rajan, Shashikant; Heideger, W. J.

doi:10.1002/aic.690170140

Cited by 21 publications

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“…There are self‐circulating flow and abundant whirlpools in the droplet signifying violent turbulence when the liquid droplets just arrive on the solid surface (shown in AB segment in Figure ). Much experimental effort has been made to investigate the mass‐transfer rate during the droplet formation . Different experimental approaches have been established such as extrapolation methods to zero formation time or zero column height, the formation‐collapse technique where the droplet is withdrawn after formation by the same nozzle, or using short column heights (see Refs.…”

Section: Mass‐transfer Coefficients In Rpbsmentioning

confidence: 99%

Dynamics of droplets and mass transfer in a rotating packed bed

Yan

Cheng

2014

AIChE Journal

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in Wiley Online Library (wileyonlinelibrary.com)To do further research on the mass-transfer mechanism in rotating packed bed (RPB), dynamics of droplets in a RPB are studied by an analytical approach combined with a series of laboratory measurements. Based on the results of the fluid dynamics, mathematical models of mass-transfer coefficient and mass-transfer process in RPB are proposed, respectively. Mass-transfer experiments in RPB are also carried out using ethanol-water solution. By comparison, the results of simulation agree well with that of the experiment, which demonstrate that both hydrodynamic model and mass-transfer models can better describe the real conditions of RPB.

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Section: Mass‐transfer Coefficients In Rpbsmentioning

confidence: 99%

Dynamics of droplets and mass transfer in a rotating packed bed

Yan

Cheng

2014

AIChE Journal

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confidence: 99%

Mass transfer during drop formation

Heideger

DuBois

1985

AIChE Journal

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In an earlier paper (Rajan and Heideger, 1971), we reported measurements of mass transfer coefficients determined photographically for extraction from single drops during formation. The system employed was continuous phase resistance controlled, and yet the mass transfer was strongly affected by circulation within the drop, especially in the early formation period. The reported coefficients generally decayed to a nearly steady value long before the drop detached from the forming nozzle, consistent with the subsequent observation (Humphrey et al., 1974) that internal circulation during drop formation can effectively cease before drop detachment. All of the results were correlated as Cumulative mass transfer = const. (formation time)n in which n varied from 0.6 to 2.4 with variation in nozzle diameter and dispersed phase flow rate.No single correlation was obtained for either instantaneous or cumulative mass transfer, because of the large number of variables affecting the exchange between phases. However, in going back to that data, we have observed that the total formation time for any drop is a good correlating parameter for the average mass transfer coefficient integrated over the formation period. Although the linear infusion velocity of the dispersed phase fluid should obviously be important in establishing internal circulation, it appears that total formation time effectively incorporates that with nozzle size and dropdiameter to represent all of the observations. Figure 1 shows this result, in which even the measurements made at different continuous phase velocities are well correlated by a single line. W. J. HEIDEGER and S. E. DUBOIS University of WashhgtonSeattle, WA 98195Since circulation was obviously so important even in this continuous phase resistance system, we decided to make the comparable study for a system controlled by the dispersed phase resistance. Photographic measurements similar to those already reported were made, except that in the present study drops of water were formed in a stationary continuous organic phase consisting of 2-ethoxyethyl acetate. The organic was presaturated with water so that no m a s transfer occurred within the continuous phase. Thus m a s was transferred only from the interface into the forming drop and the total resistance to mass transfer at all times resided in the dispersed phase. Again, the instantaneous drop volume was determined by careful measurements on cine photographs and the mass transferred was evaluated by difference between infused volume and measured volume. RESULTSAs in the previous study, the instantaneous mass transfer coefficients were generally high at the onset of drop formation, decreased rapidly early in the formation period, and then either held constant or increased only slightly until final detachment of the drop from the nozzle. Absolute magnitudes of the coefficients are different from those determined for the continuous phase but, since the system's physical properties (especially diffusivity, dispersed phase viscosity, and interfacia...

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“…In a more recent but somewhat different type of work, Rajan and Heideger (1971) measured instantaneous mass transfer rates during drop formation using a two-phase system of ethyl acetoacetate drops forming in a continuous water phase. There was no solute to be transported to the interface since the transfer rates were based upon the dissolution of the ethyl acetoactate itself into the water phase.…”

Section: Discussion Of Resultsmentioning

confidence: 99%

“…More direct methods were used by Groothius and Kramers ( 1955), who calculated instantaneous mass transfer coefficients from continuous measurements of sulfur dioxide absorption in water droplets as they were being forined, and by Rajan and Heideger (1971), who mea- sured the transfer of ethyl acetoacetate into a continuous water phase as the organic droplets were forming. Both of these direct measurement techniques utilized two-component systems in which one phase was diffusing into the other.…”

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confidence: 99%

Mass transfer and internal circulation in forming drops

1976

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The presence of internal circulation in forming liquid drops has a significant effect on mass transfer rates. For the systems studied, no circulation was observed below a Reynolds number of 9.7. For Reynolds numbers between 9.7 and 34.4, transition from zero circulation to complete circulation during the entire drop formation period occurred. In studies on the rate of mass transfer from fixed volume drops with forced internal circulation, increases in mass transfer rates were found at Reynolds numbers which corresponded to those observed for the development of internal circulation patterns within the drop.

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Drop formation mass transfer

Cited by 21 publications

References 9 publications

Dynamics of droplets and mass transfer in a rotating packed bed

Dynamics of droplets and mass transfer in a rotating packed bed

Mass transfer during drop formation

Mass transfer and internal circulation in forming drops

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