Determination of Mass Transfer Coefficients on the Obtaining of Caffeine from Tea Stalk by Supercritical Carbon Dioxide With and Without Ethanol

Abstract Bioactive compound, namely piperine, was extracted from Sarawak black pepper using supercritical carbon dioxide extraction. Experiments were carried outin the range of 3,000–5,000 psi (20.7–34.4 MPa) pressures, 318–328 K temperatures, 0.4–1 mm mean particle sizes and5–10 ml/min carbon dioxide flow rates. Experimental data analysis shows that extraction yield ismainly influenced by pressure, particle size and coupled-interactions between these two variables. Extraction process was modeled accounting for intraparticle diffusion and external mass transfer. The kinetics parameters for the internal and external mass transfers were evaluated and estimated. Mass transfer correlation was also developed. From simulation results, good agreement between experimental and simulated data has been found.

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A Dissolution Kinetic Study of Disperse Dye in Supercritical Carbon Dioxide to Design an Efficient Supercritical Dyeing Process

Processes ◽

10.3390/pr9060977 ◽

2021 ◽

Vol 9 (6) ◽

pp. 977

Author(s):

Geonhwan Park ◽

Dong Eui Kwon ◽

Wonbae Kong ◽

Jimin Park ◽

Youn-Woo Lee

Keyword(s):

Carbon Dioxide ◽

Mass Transfer ◽

Supercritical Carbon Dioxide ◽

Dissolution Rate ◽

Dissolution Kinetic ◽

Process Time ◽

Dissolution Behavior ◽

Transfer Coefficients ◽

Dyeing Process ◽

Supercritical Carbon

The dissolution behavior of dye in supercritical carbon dioxide influences the overall mass transfer that controls a supercritical dyeing process. Increasing the dissolution rate of the dye leads to shortening of the dyeing process time and can improve the efficiency of the process. Controlling the properties of the carbon dioxide flow is a good method to improve the dissolution rate of dyes. In this study, a dissolution kinetic model was designed by quantitatively analyzing and formulating the dissolution phenomenon of dyes using an in situ UV/Vis spectrometer. Through this model, the dissolution rate was compared by varying the geometric shape of the column containing the dye and the flow rate of carbon dioxide. Moreover, the correlation equation between the Reynolds number and Sherwood number was obtained through mass transfer coefficients derived under various conditions. In order to verify the utility of this equation, it was applied to a scaled-up device and the precise result could be predicted. This study can be useful in the design of dyeing processes and make-up equipment.

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Determination of Volumetric Heat and Mass Transfer Coefficients in Filling Unit of Evaporative Cooling Tower

2020 International Multi-Conference on Industrial Engineering and Modern Technologies (FarEastCon) ◽

10.1109/fareastcon50210.2020.9271292 ◽

2020 ◽

Author(s):

I. Madyshev ◽

A. Dmitriev ◽

V. Kharkov

Keyword(s):

Mass Transfer ◽

Heat And Mass Transfer ◽

Cooling Tower ◽

Evaporative Cooling ◽

Transfer Coefficients ◽

Mass Transfer Coefficients ◽

Evaporative Cooling Tower

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Comparison of Existing Supercritical Carbon Dioxide Heat Transfer Correlations for Horizontal and Vertical Bare Tubes

Volume 5: Fusion Engineering; Student Paper Competition; Design Basis and Beyond Design Basis Events; Simple and Combined Cycles ◽

10.1115/icone20-power2012-54630 ◽

2012 ◽

Cited By ~ 2

Author(s):

Prabu Surendran ◽

Sahil Gupta ◽

Tiberiu Preda ◽

Igor Pioro

Keyword(s):

Heat Transfer ◽

Carbon Dioxide ◽

Supercritical Carbon Dioxide ◽

Wall Temperature ◽

Statistical Error ◽

Heat Fluxes ◽

Transfer Coefficients ◽

Bulk Fluid ◽

Heat Transfer Correlations ◽

Supercritical Carbon

This paper presents a thorough analysis of ability of various heat transfer correlations to predict wall temperatures and Heat Transfer Coefficients (HTCs) against experiments on internal forced-convective heat transfer to supercritical carbon dioxide conducted by Koppel [1], He [2], Kim [3] and Bae [4]. It should be noted the Koppel dataset was taken from a paper which used the Koppel data but was not written by Koppel. All experiments were completed in bare tubes with diameters from 0.948 mm to 9 mm for horizontal and vertical configurations. The datasets contain a total of 1573 wall temperature points with pressures ranging from 7.58 to 9.59 MPa, mass fluxes of 400 to 1641 kg/m2s and heat fluxes from 20 to 225 kW/m2. The main objective of the study was to compare several correlations and select the best of them in predicting HTC and wall temperature values for supercritical carbon dioxide. This study will be beneficial for analyzing heat exchangers involving supercritical carbon dioxide, and for verifying scaling parameters between CO2 and other fluids. In addition, supercritical carbon dioxide’s use as a modeling fluid is necessary as the costs of experiments are lower than supercritical water. The datasets were compiled and calculations were performed to find HTCs and wall and bulk-fluid temperatures using existing correlations. Calculated results were compared with the experimental ones. The correlations used were Mokry et al. [5], Swenson et al. [6] and a set of new correlations presented in Gutpa et al. [7]. Statistical error calculations were performed are presented in the paper.

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