Measurement of Overall Volumetric Mass Transfer Coefficients for Carbon Dioxide in a Well-Mixed Reactor Using a pH Probe

2006 ◽  
Vol 45 (16) ◽  
pp. 5796-5800 ◽  
Author(s):  
Gordon A. Hill
Keyword(s):  
Carbon Dioxide ◽  
Mass Transfer ◽  
Transfer Coefficients ◽  
Mass Transfer Coefficients ◽  
Ph Probe ◽  
Mixed Reactor

Dissolution of a Carbon Dioxide Bubble in a Vertical Pipe

2007 ◽  
Author(s):  
Satoru Abe ◽  
Hideaki Okawa ◽  
Shigeo Hosokawa ◽  
Akio Tomiyama
Keyword(s):  
Carbon Dioxide ◽  
Mass Transfer ◽  
Reynolds Number ◽  
Relative Velocity ◽  
Bubble Diameter ◽  
Bulk Liquid ◽  
Vertical Pipe ◽  
Transfer Coefficients ◽  
Mass Transfer Coefficients ◽  
Millipore Water

Dissolution of single carbon dioxide (CO2) bubbles in a vertical pipe of 25 mm in diameter are measured to examine the effects of the ratio λ of sphere–volume equivalent bubble diameter d to pipe diameter D, liquid Reynolds number ReL and surfactants on mass transfer. The bubble diameter d and Reynolds number ReL are varied from 5.0 to 26 mm (λ = 0.20 − 1.0) and from 0 to 3100, respectively. Millipore water, tap water and water contaminated with Triton X–100 are used for the liquid phase. Mass transfer coefficients kL are evaluated from changes in d. The kL decreases with increasing λ for bubbles in stagnant millipore water because of the decrease in bubble rising velocity due to the wall effect. Measured Sherwood numbers Sh do not depend on ReL because a turbulent fluctuation velocity in bulk liquid flow is much smaller than a relative velocity between a bubble and liquid. The mass transfer correlation for a bubble in a stagnant liquid proposed by Johnson et al. is applicable to a bubble in pipe flow, provided that a correct relative velocity between a bubble and liquid is substituted in the correlation. Due to the retardation of capillary wave, mass transfer coefficients for bubbles in contaminated water becomes smaller than those in millipore and tap waters.

Experimental Investigation of Enhanced Absorption of Carbon Dioxide in Diethanolamine in a Microreactor

2013 ◽  
Author(s):  
Harish Ganapathy ◽  
Amir Shooshtari ◽  
Serguei Dessiatoun ◽  
Mohamed Alshehhi ◽  
Michael M. Ohadi
Keyword(s):  
Carbon Dioxide ◽  
Mass Transfer ◽  
Natural Gas ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Absorption Efficiency ◽  
Optimum Operating ◽  
Transfer Coefficients ◽  
Mass Transfer Coefficients ◽  
Liquid Absorption

Natural gas in its originally extracted form comprises carbon dioxide and hydrogen sulfide as small, but non-negligible fractions of its dominant component, methane. Natural gas in the above form is typically subjected to a sweetening process that removes these acid gases. Microscale technologies have the potential to substantially enhance mass transport phenomena on account of their inherently high surface area to volume ratio. The present work reports the mass transfer characteristics during gas-liquid absorption in a microreactor. The absorption of CO2 mixed with N2 into aqueous diethanolamine was investigated in a single straight channel having a hydraulic diameter of 762 micrometer and circular cross-sectional geometry. The performance of the reactor was characterized with respect to the absorption efficiency and mass transfer coefficient. Close to 100% absorption efficiency was obtained under optimum operating conditions. Shorter channel lengths were observed to yield enhanced values of mass transfer coefficient on account of the improved utilization of the liquid reactants’ absorption capacity for a given reactor volume. In comparison to the 0.5 m long channel, the mass transfer coefficients with the 0.3 m and 0.1 m channels were higher on an average by 35.2% and 210%, respectively. Parametric studies investigating the effects of phase superficial velocity, liquid and gas phase concentration were performed. The mass transfer coefficients achieved using the present minichannel reactor were 1–3 orders of magnitude higher than that reported using conventional gas-liquid absorption systems.

scholarly journals Extraction of Clove and Vetiver Oils with Supercritical Carbon Dioxide: Modeling and Simulation

2007 ◽  
Vol 1 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Julian Martínez ◽  
Paulo T.V. Rosa ◽  
M. Angela A. Meireles
Keyword(s):  
Carbon Dioxide ◽  
Mass Transfer ◽  
Large Scale ◽  
Raw Material ◽  
Feed Ratio ◽  
Transfer Model ◽  
Transfer Coefficients ◽  
Mass Transfer Coefficients ◽  
Extraction Curve ◽  
Kinetics Of

The kinetics of supercritical fluid extraction (SFE) of clove and vetiver oils using carbon dioxide as solvent was studied, in order to establish an efficient method to predict extraction curves on large scale. The mass transfer model of Sovová was used to adjust the experimental SFE data, which were obtained at 100 bar and 35 °C for clove and 200 bar and 40 °C for vetiver, using extraction columns of different geometry and solvent flow rates. Some other process parameters, such as bed density and porosity, solvent to feed ratio and solvent velocity were kept constant from one experiment to another, in order to verify if the mass transfer coefficients adjusted by the model varied. The results show that the model of Sovová was able to predict an overall extraction curve for clove from data obtained with twenty times less raw material, since the mass transfer coefficients remained the same and the predicted curves were similar to the observed ones. For vetiver, the simulation was not as effective, probably due to the effects of transport properties on the process.

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