Mass Transfer Resistance Analysis and Semipermeable Membrane Optimization for Pressure Retarded Osmosis

2011 ◽  
Vol 361-363 ◽  
pp. 1416-1421
Author(s):  
Yong Hua You ◽  
Xi Lai Zhang ◽  
Zhi Lin Wu ◽  
Xiang Fei Yu ◽  
Shi Ping Jin ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Power Density ◽  
Sea Water ◽  
Water Flux ◽  
Solute Diffusion ◽  
Mass Transfer Resistance ◽  
Transfer Resistance ◽  
Pressure Retarded Osmosis

Salinity power is a promising renewable energy with a large amount, which can be tapped by pressure retarded osmosis(PRO), however, efficient membranes are in lack. It was reported subtrates of asymmetrical reverse osmosis(RO) membranes had severe concentration polarizations in PRO process, degrading performance greatly and limiting PRO application. Based on solute transportation equations, the paper presented a common mass transfer resistance model of osmosis process, and disclosed essential differences between PRO and RO by the comparison of resistances. In PRO water permeates through membranes against solute diffusion, which facilitates solute to accumulate in porous subtrate, as a result, subtrate mass transfer resistance is big, water flux and power density is small, especially in the case of trivial subtrate mass transfer coefficient. Commercial RO membrane CA-3000 was studied for PRO application, whose subtrate resistance was found much bigger in PRO, taking the majority of total resistance. Subtrate was optimized for PRO process and membrane performance was projected. When subtrate mass transfer coefficient was improved to 4×10-6 m/s, power density of 4.75 W/m2 was obtained with average sea water, which approached the threshold of commercial salinity power exploitation.

Linear Driving Force Model in Carbon Dioxide Capture by Adsorption

2016 ◽  
Vol 830 ◽  
pp. 38-45 ◽  
Author(s):  
Leonardo Hadlich de Oliveira ◽  
Joziane Gimenes Meneguin ◽  
Edson Antonio da Silva ◽  
Maria Angélica Simões Dornellas de Barros ◽  
Pedro Augusto Arroyo ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Breakthrough Curve ◽  
Driving Force ◽  
Fixed Bed ◽  
Isotherm Models ◽  
Force Model ◽  
Transfer Resistance ◽  
Linear Driving Force

In this work, experimental data of CO2 capture by adsorption was determined gravimetrically, at 30 °C and pressures up to 40 bar, and in a fixed bed unit at 20 bar, using NaY as adsorbent. Langmuir, Sips and Tóth isotherm models were used to correlate the equilibrium data. Sips and Tóth models were best fitted allowing estimate the maximum CO2 adsorbed amount. The breakthrough curve was modeled using Linear Driving Force (LDF) and Thomas models. The LDF model represented better the CO2 breakthrough curve than Thomas model. The mass transfer resistance in NaY micropores can be assumed as the limiting step for CO2 adsorption in fixed bed, since the intraparticle mass transfer coefficient of LDF model was smaller than the experimental overall volumetric mass transfer coefficient, although external film resistance is not negligible.

Experimental Investigation of the Effects of Surfactants on the Mass Transfer in Liquid-Liquid Extraction Equipments

2007 ◽  
Author(s):  
A. Haghdoost ◽  
M. Shah-Alami ◽  
H. Mansouri
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Terminal Velocity ◽  
Liquid Extraction ◽  
Drop Diameter ◽  
Transfer Resistance ◽  
Transfer Rates ◽  
Liquid Liquid Extraction ◽  
Triton X

Mass transfer rates to the drops in liquid-liquid extraction equipment are often likely to be reduced by the presence of surface active contaminants. This reduction in mass transfer is said to be due to a reduction in terminal velocity, and to changes in pattern of internal circulation. A single-drop extraction apparatus was used to investigate the dependency of mass transfer coefficient on the amount of surfactant added in a system of n-butanol/succinic acid/water. Three types of surfactants, SDS, DTMAC and Triton X-100, were used to study their effects on the inhibition of mass transfer in liquid-liquid extraction. The effect of surfactants concentration on extraction percentage, overall mass transfer coefficient, and extra mass transfer resistance was investigated for these surfactants. Also variation of terminal velocity as a function of surfactant concentration and drop diameter were illustrated for both surfactants. Finally these surfactants were compared to each other.

scholarly journals Gas Holdup and Gas-Liquid Mass Transfer Investigations in an Oscillatory Flow in a Baffled Column

2008 ◽  
Vol 2 (1) ◽  
pp. 7
Author(s):  
Taslim Taslim ◽  
Mohd Sobri Takriff
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Power Density ◽  
Volume Fraction ◽  
Gas Holdup ◽  
Gas Velocity ◽  
Liquid Mass ◽  
Liquid Mass Transfer ◽  
Superficial Gas Velocity

Gas holdup and gas-liquid mass transfer were investigated in a vertical baffled column. Pure carbon dioxide (C02) was used as the dispersed phase and tap water was used as the continuous phase. Gas holdup and mass transfer rate of C02 were measured under semi-batch condition, while the liquid phase was measured in batch mode. Gas holdup was estimated as the volume fraction of the gas in the two-phase mixture in the column. Mass transfer was expressed in terms of the liquid-side volumetric mass transfer coefficient (kLa). The effects of oscillation frequency, oscillation amplitude and gas flow rate on gas holdup andmass transfer were also determined. The results showed that a significant increase in gas holdup and mass transfer could be achieved in an oscillatory baffled column compared to a bubble column. Gas holdup and mass transfer were correlated as a function of power density and superficial gas velocity. Keywords: gas holdup, mass transfer coefficient, power density, superficial gas velocity

scholarly journals Calculation of the Mass Transfer Coefficient for the Dissolution of Multiple Carbon Dioxide Bubbles in Sea Water under Varying Conditions

2019 ◽  
Vol 7 (12) ◽  
pp. 457
Author(s):  
Hee-Joo Cho ◽  
Jungho Choi
Keyword(s):  
Carbon Dioxide ◽  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Bubble Size ◽  
Retention Time ◽  
Time Pressure ◽  
Sea Water ◽  
Weapon Systems ◽  
Carbon Dioxide Gas

Underwater weapon systems with reforming fuel cells have been developed to increase the number of possible days that the former can be submerged. Reforming hydrocarbons generate a large quantity of carbon dioxide gas that must be completely dissolved in water and released. In this study, the mass transfer coefficient was derived experimentally while changing the process variables that affect mass transfer, such as bubble size, presence/absence of an inline mixer, retention time, pressure, and solvent type. It was found that retention time was most affected, followed by type of solvent, presence/absence of the inline mixer, and bubble size. In addition, by reducing bubble size and retention time and applying an inline mixer, the effect can be like that dissolved at high pressure even at low pressure. Applications of this study are expected to reduce the size of underwater weapon systems. Therefore, further studies on increasing the power consumption of underwater weapon systems due to reduction of bubble size and the application of inline mixers should be conducted.

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