Effect of Axial Mixing on Mass Transfer in Extraction Columns

Li, N. N.; Ziegler, Edward N.

doi:10.1021/ie51402a008

Cited by 17 publications

(7 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As expected, the mass transfer coefficients obtained by the plug flow model are larger (on average 12 %) than those obtained by the axial dispersion model. In other words, axial mixing reduced the mass transfer coefficient by an average of 12 % but not as much as that reported by Li and Ziegler (about 30 %) . The reason for this will be demonstrated in the next section.…”

Section: Resultsmentioning

confidence: 69%

“…In other words, axial mixing reduced the mass transfer coefficient by an average of 12 % but not as much as that reported by Li and Ziegler (about 30 %). [19] The reason for this will be demonstrated in the next section. Figure 5 also illustrates that the overall mass transfer coefficients for butyl are greater than those for toluene in the same condition.…”

Section: The Volumetric Overall Mass Transfer Coefficientmentioning

confidence: 94%

“…In fact, the axial dispersion model, which has been developed well, is the modified ideal plug flow model since it considers the unfavourable effect of the axial mixing. It has been reported that the axial dispersion can even reduce the mass transfer efficiency up to 30 % …”

Section: Methodsmentioning

confidence: 99%

“…It has been reported that the axial dispersion can even reduce the mass transfer efficiency up to 30 %. [19] As shown in Figure 2b, the solute material balance leads the following set of equations at steady state conditions: [39] − − ( − ) = (12) and (13) require two pairs of boundary conditions to be simultaneously solved numerically. The boundary condition that uses the entrance solute concentration can be defined as follows: [40] ( )…”

Section: Modellingmentioning

confidence: 99%

“…[17] For example, Li and Ziegler [19] have determined that the axial mixing of the liquids diminishes the mass transfer performance up to 30 %. [19] Therefore, a reliable correlation is needed to determine the axial mixing coefficient in addition to mass transfer coefficient for designing an extractor. A significant amount of research has been carried out on axial mixing in extraction columns.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Use of axial dispersion and plug flow models for determination of axial mixing and mass transfer coefficient in an l‐shaped pulsed packed extraction column

et al. 2019

View full text Add to dashboard Cite

In this study, the volumetric overall mass transfer and phases axial mixing coefficients have been investigated in a pilot plant of an L‐shaped pulsed packed extraction column by using two liquid systems of toluene/acetone/water and n‐butyl/acetone/water. The mass transfer performance has been evaluated using two methods of axial dispersion and a plug flow model. The effect of the operational variables and physical properties, including the dispersed and continuous phases flow rates, pulsation intensity, and interfacial tension, on mass transfer and phases axial mixing coefficients have been considered. It has been found that the pulsation intensity and the continuous phase flow rate seriously affect the mass transfer coefficient, however, the dispersed phase flow rate has a weaker effect. Also, the axial mixing of a phase is strongly affected by the pulsation intensity and the flow rate of the phase itself and it is not affected by the second phase flow rate. Finally, new correlations are proposed to accurately predict the mass transfer and axial mixing coefficients.

show abstract

Section: Resultsmentioning

confidence: 69%

Section: The Volumetric Overall Mass Transfer Coefficientmentioning

confidence: 94%

Section: Methodsmentioning

confidence: 99%

Section: Modellingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Use of axial dispersion and plug flow models for determination of axial mixing and mass transfer coefficient in an l‐shaped pulsed packed extraction column

et al. 2019

View full text Add to dashboard Cite

show abstract

Longitudinal dispersion of liquid flowing through fixed and fluidized beds

1968

View full text Add to dashboard Cite

Longitudinal liquid mixing in fluidized and fixed beds was studied using sinusoidal and pulse response techniques. The tracer used was light emissive fluorescein dye. A systematical study of liquid phase dispersion by varying particle size, fluid velocity, fraction voids, and particle density was conducted. A generalized correlation applicable to both fixed bed and fluidized bed was obtained. The application of the correlation in predicting the effect of the dispersion on reactor performance was discussed.The study of fluid mixing in a continuous flow system is of considerable importance for the design of chemical reactors. Neglecting the fluid dispersion may result in an overestimation of the conversion, the driving force, and the volume efficiency of the system. In order to estimate the dispersion coefficient in a continuous flow reactor, the dynamic response method has been generally applied. This method involves injecting a tracer into the system according to a certain function and matching the response curve with that derived from the mathematicaI model. The parameters characterizing the mixing or dispersion of the fluid in the system are then evaluated from the best fitted mathematical curve.In this work, experiments have been performed by using sinusoidal and pulse inputs of fluorescein tracer to fixed beds and fluidized beds. A systematic study of liquid phase dispersion has been conducted, particularly, the effects of particle size, fluid velocity, fraction voids, and particle density have been considered. Based on the knowledge of the ef€ect of individual factors on the dispersion coefficient and the correlations suggested by the previous investigators, a generalized correlation valid for both fixed beds and fluidized beds has been obtained. A large number of fixed bed data and fluidized bed data from literature were also incorporated into this correlation in order to confirm its validity. This work is limited to the study of liquid phase mixing in particulate systems consisting of uniform size particles. Table 1 shows a summary of the previous investigations on the longitudinal dispersion of liquid in fixed beds. Although there has been a large number of investigations on the fluid dispersion in fixed beds, only a few studies are available on the loiigitudinal dispersion of liquid in fluidized beds as shown in Table 2. The information obtained from the previous investigations on liquid mixing in fixed and fluidized beds have been fragmentary. So far no correlation that ties together the longitudinal dispersion in fixed beds with that in fluidized beds has been availabIe. The usual method of correlation of the Iongitudinal dispersion is by plotting either the Peclet number vs. the Reynolds number, or the dimensionless dispersion group, Exp/p, vs. the Reynolds, or by relating some dimensionless groups involving voidage, e. For the fixed bed, plots of the Peclet number vs. the Reynolds number has been commonly employed (10, 15, 20, 36, 37, 41, 49). However, disagreements in the magnitude of the Peclet num...

show abstract

Supercapacitor Degradation: Understanding Mechanisms of Cycling‐Induced Deterioration and Failure of a Pseudocapacitor

Mazloomian

Lancaster

Howard

et al. 2023

Batteries & Supercaps

View full text Add to dashboard Cite

Owing to a reputation for long lifetimes and excellent cycle stability, degradation in supercapacitors has largely been overlooked. In this work, we demonstrate that significant degradation in some commercial supercapacitors can in fact occur early in their life, leading to a rapid loss in capacitance, especially when utilized in full voltage range, high charge‐discharge frequency applications. By using a commercial 300 F lithium‐ion pseudocapacitor rated for 100,000 charge/discharge cycles as an example system, it is shown that a ∼96 % loss in capacitance over the first ∼2000 cycles is caused by significant structural and chemical change in the cathode active material (LiMn2O4, LMO). Multi‐scale in‐situ and ex‐situ characterization, using a combination of X‐ray computed tomography, Raman spectroscopy and X‐ray photoelectron spectroscopy, shows that while minimal material loss (∼5.5 %), attributed to the dissolution of Mn2+, is observed, the primary mode of degradation is due to manganese charge disproportionation (Mn3+→Mn4++Mn2+) and its physical consequences (i. e. microstrain formation, particle fragmentation, loss of conductivity etc.). In contrast to prior understanding of LMO material degradation in battery systems, negligible contributions from cubic‐to‐tetragonal phase transitions are observed. Hence, as supercapacitors are becoming more widely utilized in real‐world applications, this work demonstrates that it is vital to understand the mechanisms by which this family of devices change during their lifetimes, not just for lithium‐ion pseudocapacitors, but for a wide range of commercial chemistries.

show abstract

Effect of Axial Mixing on Mass Transfer in Extraction Columns

Cited by 17 publications

References 33 publications

Use of axial dispersion and plug flow models for determination of axial mixing and mass transfer coefficient in an l‐shaped pulsed packed extraction column

Use of axial dispersion and plug flow models for determination of axial mixing and mass transfer coefficient in an l‐shaped pulsed packed extraction column

Longitudinal dispersion of liquid flowing through fixed and fluidized beds

Supercapacitor Degradation: Understanding Mechanisms of Cycling‐Induced Deterioration and Failure of a Pseudocapacitor

Contact Info

Product

Resources

About