Influence of Physical Properties of Phases on Hydrodynamics and Mass Transfer Characteristics of a Liquid-Liquid Circular Microchannel

2016 ◽  
Author(s):  
Mehdi Sattari-Najafabadi ◽  
Bengt Sundén ◽  
Zan Wu ◽  
Mohsen Nasr Esfahany
Keyword(s):  
Mass Transfer ◽  
Physical Properties ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Flow Rate ◽  
Rate Ratio ◽  
Operating Conditions ◽  
Flow Rate Ratio ◽  
Internal Diameter ◽  
Volumetric Mass Transfer Coefficient

The influences of operating conditions and physical properties of the two phases on the hydrodynamics and mass transfer in a circular liquid-liquid microchannel have been investigated. The polytetrafluoroethylene (PTFE) microchannel has an internal diameter of 0.7 mm and a T-shaped mixing junction. Sodium hydroxide solution was used as the aqueous phase. N-hexane and toluene were employed as the organic phases to investigate the effect of physical properties. Regarding the results, at constant total flow rate, raising the flow rate ratio enhanced the overall volumetric mass transfer coefficient. Using toluene as the organic solvent enhanced the overall volumetric mass transfer coefficient in average by 64.7% and 100.27% comparing to n-hexane-water at flow rate ratio of 1 and 0.5, respectively. This increment resulted in a decrement in the required mass transfer time and length in the microchannel. The length of the slugs had no considerable variation as n-hexane was replaced with toluene. Thus, the significant improvement of the overall volumetric mass transfer coefficient was because of the increment of the overall mass transfer coefficient, not the specific interfacial area.

scholarly journals Optimization in the Absorption and Desorption of CO2 Using Sodium Glycinate Solution

2018 ◽  
Vol 8 (11) ◽  
pp. 2041 ◽  
Author(s):  
Pao Chi Chen ◽  
Sheng-Zhong Lin
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Flow Rate ◽  
Bubble Column ◽  
Absorption Efficiency ◽  
Operating Conditions ◽  
Flow Rate Ratio ◽  
Optimum Operating ◽  
Co2 Absorption

This study used sodium glycinate as an absorbent to absorb CO2 in the bubble column scrubber under constant pH and temperature environments to obtain the operating range, CO2 loading, and mass transfer coefficient. For efficient experimentation, the Taguchi method is used for the experimental design. The process parameters are the pH, gas flow rate (Qg), liquid temperature (T), and absorbent concentration (CL). The effects of the parameters on the absorption efficiency, absorption rate, overall mass transfer coefficient, gas–liquid molar flow rate ratio, CO2 loading, and absorption factor are to be explored. The optimum operating conditions and the order of parameter importance are obtained using the signal/noise (S/N) ratio analysis, and the optimum operating conditions are further verified. The verification of the optimum values was also carried out. The order of parameter importance is pH > CL > Qg > T. Evidence in the 13CNMR (Carbon 13 Nuclear Magnetic Resonance) spectra shows that the pH value has an effect on the solution composition, which affects both the absorption efficiency and mass transfer coefficient. There are 18 experiments for regeneration, where the operating temperature is 100–120 °C. The heat of regeneration was measured according to the thermodynamic data. The CO2 loading, the overall mass transfer, and the heats of regeneration correlation are also discussed in this work. Finally, an operating policy for the CO2 absorption process was confirmed.

scholarly journals Mass Transfer Correlation and Optimization of Carbon Dioxide Capture in a Microchannel Contactor: A Case of CO2-Rich Gas

Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5465
Author(s):  
Nattee Akkarawatkhoosith ◽  
Wannarak Nopcharoenkul ◽  
Amaraporn Kaewchada ◽  
Attasak Jaree
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Flow Rate ◽  
Co2 Capture ◽  
Volumetric Flow Rate ◽  
Absorption Efficiency ◽  
Operating Conditions ◽  
Molar Ratio ◽  
Volumetric Mass Transfer Coefficient

This work focused on the application of a microchannel contactor for CO2 capture using water as absorbent, especially for the application of CO2-rich gas. The influence of operating conditions (temperature, volumetric flow rate of gas and liquid, and CO2 concentration) on the absorption efficiency and the overall liquid-side volumetric mass transfer coefficient was presented in terms of the main effects and interactions based on the factorial design of experiments. It was found that 70.9% of CO2 capture was achieved under the operating conditions as follows; temperature of 50 °C, CO2 inlet fraction of 53.7%, total gas volumetric flow rate of 150 mL min−1, and adsorbent volumetric flow rate of 1 mL min−1. Outstanding performance of CO2 capture was demonstrated with the overall liquid-side volumetric mass transfer coefficient of 0.26 s−1. Further enhancing the system by using 2.2 M of monoethanolamine in water (1:1 molar ratio of MEA-to-CO2) boosted the absorption efficiency up to 88%.

scholarly journals Determination of the ozone volumetric mass transfer coefficient in bubble column with two-fluid nozzle gas distributor

2015 ◽  
Vol 69 (5) ◽  
pp. 553-559 ◽  
Author(s):  
Milica Djekovic-Sevic ◽  
Nevenka Boskovic-Vragolovic ◽  
Ljiljana Takic ◽  
Radmila Garic-Grulovic ◽  
Srdjan Pejanovic
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Bubble Column ◽  
Operating Conditions ◽  
Volumetric Mass Transfer Coefficient ◽  
Gas Distributor ◽  
Liquid Mass Transfer ◽  
Two Fluid

Experimental investigation of gas-liquid mass transfer of ozone in water, in bubble column with two-fluid nozzle gas distributor (BKDM), under different operating conditions, are presented in this work. The main objective was to determine the ozone volumetric mass transfer coefficient, kL a, in calm uniform section of the column, under different values of gas and liquid flow rates. Obtained values of these coefficients were compared with the values in countercurrent bubble column. The critical liquid flowrate, when gas hold up reaches its maximum, was experimentally determined. It was shown that the maximum value of the ozone volumetric mass transfer coefficient is obtained just when liquid flowrate is at its critical value.

scholarly journals Mass Transfer in Multiphasic Gas/Liquid/Liquid Systems. KLa Determination Using the Effectiveness-Number of Transfer Unit Method

Processes ◽  
2018 ◽  
Vol 6 (9) ◽  
pp. 156 ◽  
Author(s):  
Éric Dumont
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Flow Rate ◽  
Gas Flow ◽  
Absorption Capacity ◽  
Operating Conditions ◽  
Transfer Unit ◽  
Liquid Systems ◽  
Overall Mass Transfer Coefficient

The Effectiveness-Number of Transfer Unit method (ε-NTU method) was applied to determine the overall mass transfer coefficient, KLa, of operating gas-liquid absorbers treating Volatile Organic Compounds (VOCs). This method requires the knowledge of the operating conditions (gas flow rate, QG; liquid flow rate, QL; scrubber volume V), the measurement of gaseous concentrations at the inlet, CGin, and at the outlet, CGout, of the contactor (in order to determine the effectiveness of the absorber ε) and the calculation of the Henry coefficient of the VOC between the gas and the liquid phases (HVOC). Coupled with the “equivalent absorption capacity” concept, the ε-NTU method was used to determine KLa of absorbers contacting a gas and a mixture of water and a Non Aqueous Phase, successfully. The method, validated from literature data for configurations countercurrent scrubbers and stirred tank reactors, could be used to simply determine the overall mass transfer coefficient of systems for which the standard KLa determination methods still remain non-reliable or inaccurate (viscous solvents, mixture of immiscible liquids, fermentation broths…).

scholarly journals Ozone absorption in a mechanically stirred reactor

2007 ◽  
Vol 72 (8-9) ◽  
pp. 847-855 ◽  
Author(s):  
Ljiljana Takic ◽  
Vlada Veljkovic ◽  
Miodrag Lazic ◽  
Srdjan Pejanovic
Keyword(s):  
Mass Transfer ◽  
Liquid Phase ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Plug Flow ◽  
Operating Conditions ◽  
Volumetric Mass Transfer Coefficient ◽  
Pseudo First Order Reaction ◽  
Ozone Absorption ◽  
Stirred Reactor

Ozone absorption in water was investigated in a mechanically stirred reactor, using both the semi-batch and continuous mode of operation. A model for the precise determination of the volumetric mass transfer coefficient in open tanks without the necessity of the measurement the ozone concentration in the outlet gas was developed. It was found that slow ozone reactions in the liquid phase, including the decomposition of ozone, can be regarded as one pseudo-first order reaction. Under the examined operating conditions, the liquid phase was completely mixed, while mixing in a gas phase can be described as plug flow. The volumetric mass transfer coefficient was found to vary with the square of the impeller speed. .

scholarly journals Effects of geometric parameters on volumetric mass transfer coefficient of non-Newtonian fluids in stirred tanks

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Haider Ali ◽  
Sofia Zhu ◽  
Jannike Solsvik
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Gas Flow ◽  
Scale Up ◽  
Pilot Scale ◽  
Operating Conditions ◽  
Volumetric Mass Transfer Coefficient ◽  
Transfer Coefficients ◽  
Stirred Tanks

Abstract Scaling up stirred tanks is a significant challenge because of the research gaps between laboratory and industrial-scale setups. It is necessary to understand the effects of scale-up on the mass transfer in stirred tanks, and this requires meticulous experimental analysis. The present study investigates the effects of tank size and aspect ratio ( H L T ${H}_{L}}{T}$ ) on the volumetric mass transfer coefficients of shear-thinning fluids. The experiments were conducted in three stirred tanks of different sizes (laboratory and pilot scale) and geometries (standard and nonstandard). H L T ${H}_{L}}{T}$ was 1 for the standard tanks and 3.5 for the nonstandard stirred tanks. Three sizes of stirred tanks were used: 11 L with H L T ${H}_{L}}{T}$ of 1, 40 L with H L T ${H}_{L}}{T}$ of 3.5, and 47 L with H L T ${H}_{L}}{T}$ of 1. Impeller stirring speeds and gas flow rates were in the range of 800–900 rev min−1 and 8–10 L min−1, respectively. The volumetric mass transfer coefficient was estimated based on the dissolved oxygen concentration in the fluids, and the effects of rheology and operating conditions on the volumetric mass transfer coefficient were observed. The volumetric mass transfer coefficient decreased as tank size increased and increased with an increase in operating conditions, but these effects were also clearly influenced by fluid rheology. The impacts of scale-up and operating conditions on the volumetric mass transfer coefficient decreased as liquid viscosity increased.

scholarly journals Effect of pH and Gas Flow Rate on Ozone Mass Transfer of Κ-Carrageenan Solution in Bubble Column Reactor

REAKTOR ◽  
2019 ◽  
Vol 18 (04) ◽  
pp. 177 ◽  
Author(s):  
Aji Prasetyaningrum ◽  
Dyah Arum Kusumaningtyas ◽  
Purbo Suseno ◽  
Ratnawati Ratnawati
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Flow Rate ◽  
Gas Flow ◽  
Bubble Column ◽  
Operating Conditions ◽  
Bubble Column Reactor ◽  
Gas Flow Rate ◽  
Column Reactor

This research was conducted to calculate the mass transfer coefficient value for ozonation reaction of κ-carrageenan solution in the bubble column reactor. Ozone gas was produced using ozone generator type corona discharge. In this study, operating conditions were regulated at ozone gas flow rate 2- 5 L min-1, pH 4-10, and temperature 29 ± 1 oC. Samples were tested every 5 minutes to determine the dissolved ozone concentration. The results showed that dissolved ozone concentrations increased with increasing ozonation time and ozone gas flow rate. However, a very high gas flow rate can increase turbulence so that the mass transfer coefficient (kLa) value decreased. In alkaline conditions, the formation of free radicals (HO*) increases so that the amount of dissolved ozone decreases. The kLa value of ozone gas in κ-carrageenan solution is slightly lower than the kLa value of the ozone gas in the water. The results of this study indicate that (kLa) ozone gas in water is 0.131 / minute while the value (kLa) in κ-carrageenan solution is 0.128 / minute.

Dispersed air flotation as a pretreatment process for seawater desalination

2012 ◽  
Vol 12 (4) ◽  
pp. 431-438 ◽  
Author(s):  
Hossam Altaher ◽  
Emad ElQada ◽  
Waid Omar
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Flow Rate ◽  
Seawater Temperature ◽  
Operating Conditions ◽  
Oxygen Absorption ◽  
Aeration Tank ◽  
Overall Mass Transfer Coefficient ◽  
Air Flotation

Pretreatment of seawater before reverse osmosis (RO) processes with dispersed air flotation involves a change in oxygen concentration in seawater. In order to understand this phenomenon, a series of experimental aeration studies was conducted. Aeration tests were performed under different operating conditions of seawater temperature, flow rate of the air and depth of the water in the aeration tank. The experimental results show that the overall mass transfer coefficient increases by increasing air flow rate. A measured increase in the overall mass transfer coefficient was observed with elevation of the temperature from 24 to 38 °C. The estimated value of activation energy of oxygen absorption in seawater is 42.5 kJ/mol. The value of the overall mass transfer coefficient is found to be affected by diffuser type and stirrer speed as these parameters influence the bubble size and the surface area available for mass transfer of oxygen from air bubbles to seawater.

Absorption of oxygen into solutions of polymers

1986 ◽  
Vol 51 (10) ◽  
pp. 2127-2134 ◽  
Author(s):  
František Potůček ◽  
Jiří Stejskal
Keyword(s):  
Mass Transfer ◽  
Aqueous Solutions ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Flow Rate ◽  
Liquid Flow ◽  
Flow Curve ◽  
Liquid Flow Rate ◽  
Polymer Concentration ◽  
Newtonian Liquids

Absorption of oxygen into water and aqueous solutions of poly(acrylamides) was studied in an absorber with a wetted sphere. The effects of changes in the liquid flow rate and the polymer concentration on the liquid side mass transfer coefficient were examined. The results are expressed by correlations between dimensionless criteria modified for non-Newtonian liquids whose flow curve can be described by the Ostwald-de Waele model.

Sign in / Sign up

Export Citation Format

Share Document