scholarly journals Ionic Mass Transfer at Point Electrodes Located at Cathode Support Plate in an Electrorefining Cell in Presence of Rectangular Turbulent Promoters

2022 ◽  
Vol 14 (2) ◽  
pp. 880
Author(s):  
Tondepu Subbaiah ◽  
Ponnam Vijetha ◽  
Barsha Marandi ◽  
Kali Sanjay ◽  
Manickam Minakshi
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Flow Rate ◽  
Current Density ◽  
Limiting Current ◽  
Forced Circulation ◽  
Support Plate ◽  
Limiting Current Density ◽  
Overall Mass Transfer Coefficient

Current density plays a major role in deciding the plant size, current efficiency, and energy consumption in electrorefining cells. In general, operating current density will be 40% of the limiting current density. Forced circulation of the electrolyte in the presence of promoters improves the mass transfer coefficient. In the present study, rectangular turbulence promoters are fitted at the bottom side of the cell to improve the mass transfer coefficient at the cathode support plate. The limiting current density technique is used to measure the mass transfer coefficient. The variables covered in the present study are the effects of flow rate, promoter height, and spacing among the promoters. The electrolyte consists of copper sulfate and sulphuric acid. At a regulated flow rate, the electrolyte is pumped from the recirculation tank to the cell through an intermediate overhead tank. The limiting current density increased with an increasing flow rate in the presence of promoters, and thus the overall mass transfer coefficient on the cathode support plate also improved. With an increase in the flow rate of the electrolyte from 6.67 × 10−6 to 153.33 m3/s, limiting current density increased from 356.8 to 488.8 A/m2 for spacing of 0.30 m, with a promoter height of 0.01 m. However, it is noteworthy that when the promoter height is increased from 0.01 to 0.07 m, the overall mass transfer coefficient is found to increase up to 60%, but with the further increase in the promoter height to 0.30 m the mass transfer coefficient starts to decrease. Therefore, the optimized cell parameters are established in this work. The current sustainable concept of employing rectangular turbulence promoters will bring benefits to any precious metal refining or electrowinning tank house electrolytes.

scholarly journals An Experimental Investigation of Overall Mass Transfer coefficient ( K_Ga ) of 〖CO〗_2 absorption using Monoethanolamine(MEA) and Diethanolamine(DEA) in a Bubble Column Reactor (BCR)

2020 ◽  
Vol 13 (1) ◽  
pp. 67-73
Author(s):  
Elaf Thamera ◽  
Salih Abduljabbar Rushdi
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Flow Rate ◽  
Gas Flow ◽  
Bubble Column ◽  
Bubble Column Reactor ◽  
Air Flow Rate ◽  
Column Reactor ◽  
Overall Mass Transfer Coefficient

In this work, an absorption technology   was used actually to investigation the  mass transfer coefficient of carbon dioxide from a gaseous mixture (air, carbon dioxide) in  blended solution Monoethanolamine (MEA) and Diethanolamine (DEA)  in a bubble column reactor (BCR) . The bubble column reactor(BCR) was made of Plexiglas with 1.5 m high and 0.1 m inside diameter. The overall mass transfer coefficient (  was evaluated at different operating conditions , gas flow rate, air Flow rate ,liquid flow rate .Where the gas flow rates were 10, 15 and 20 L /min ,  air flow rate 100,150 and 200 L/h ,and liquid flow rate 5 ,10,15 L /min . This experiment  by   using  continuous   process with helping centrifugal  pump  . High-performance gas chromatographic (GC) was performed to evaluate  loading during absorption experiment . The  experimental results have shown that the   loading in range of  0.581-1.367 (mol  /mole amine),and the maximum value of overall mass transfer coefficient ( KG) was 0.04 S-1 .

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 Investigation of overall mass transfer coefficient of CO2 absorption in packed Column

2020 ◽  
Vol 13 (2) ◽  
pp. 153-157
Author(s):  
Zahraa N. Abd ◽  
Salih A. Rushdi
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Flow Rate ◽  
Liquid Flow ◽  
Gas Flow ◽  
Continuous Process ◽  
Packed Bed Reactor ◽  
Absorption Time ◽  
Overall Mass Transfer Coefficient

Mixtures of different types of amine solution Monoethanolamine, Diethanolamine, and Triethanolamine were experimentally used to investigate the overall mass transfer coefficient (KGa) at different operating parameters. The experiments were made in a packed bed reactor (PBR) with 75 cm in high and10 cm inside diameter as a gas-liquid contactor at 25℃ and atmospheric pressure, using a simulation gaseous mixture (air, carbon dioxide)  with recycle stream (semi-continuous process). Experimental design process Taguchi was employed. Four factors and three levels were chosen and exploded using L9 (3 ^4) orthogonal array design. These parameters for semi-continuous  process were namely: gas flow rate 5,10,and 15 L/min ,airflow rate80,90,and 100 L/h, liquid flow rate 400,450,and 500 mL/min  and time absorption time  30,45,and 60min . A Shimadzu GC-8A Gas Chromatograph with a thermal conductivity detector was used to measure the CO2 concentration absorbed in aqueous blended solution. The maximum value for CO2 loading was 8.622 (mol CO2/mol amine) at 15 L/min gas flow and 450 mL/min liquid flow and 100 L/h airflow for 60 min from absorption time. The results showed that the max value of KGa is 0.048 S-1.

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.

scholarly journals Packed bed absorption column: Hydrodynamics and mass transfer

2019 ◽  
pp. 260-267
Author(s):  
Milan Sovilj ◽  
Branislava Nikolovski ◽  
Momcilo Spasojevic ◽  
Sinisa Mauhar
Keyword(s):  
Mass Transfer ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Flow Rate ◽  
Gas Mixture ◽  
Countercurrent Flow ◽  
Air Velocity ◽  
Absorption Column ◽  
Overall Mass Transfer Coefficient

This paper presents the results of the determination of the hydrodynamic characteristics and mass transfer in the pilot plate absorption column. The experimental values of the pressure drop in the countercurrent flow of air and water through the column were obtained. The graphic dependence of the pressure drop of air per unit height of the layer of packing (?P/h) on the apparent air velocity (Ug) through the dry charge was shown to be in the form of a quadratic function. From the graphical function which shows the dependence of the pressure drop per unit height of the layer of filling (?P/m) on the apparent air velocity during the countercurrent flow of the phases (water and air), three fields of the interaction of the phases were observed: a) the area of low load, at low apparent air velocities, b) the area of high load, at higher air velocities, and c) the flooding area, when the liquid completely fills the cavities and the working gas in them starts bubbling. The overall mass transfer coefficient (Kg) of the air-CO2-water system depends on the flow rate of the gaseous phase and the composition of the starting gas mixture (air-CO2). With the increase in the total gas flow rate, with a constant composition of the starting gas mixture and constant fluid flow, the overall mass transfer coefficient increases. Increasing the amount of CO2 in the starting gas mixture at a constant flow rate of fluid and a constant ratio of the molar flow of the inert in the liquid and the gas-phase (L'/G') decreases the overall mass transfer coefficient.

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.

Modeling Vapor Transport in a Hollow Fiber Membrane Humidifier Using ε-NTU Approach

2020 ◽  
Author(s):  
Hoang Nghia Vu ◽  
Xuan Linh Nguyen ◽  
Sangseok Yu
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Fuel Cell ◽  
Relative Humidity ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Water Content ◽  
Vapor Transport ◽  
Overall Mass Transfer Coefficient ◽  
Mass Exchanger

Abstract In a fuel cell vehicle, the water content of the gas supply within certain ranges plays a key role in improving the performance of a proton exchange membrane. The lower limit of water content in the air supply is to avoid the problem of drying-out, while the upper prevents flooding. Water management can be accomplished by a membrane humidifier which allows water vapor to permeate the mixture from the side having the higher water concentration, moving to the other side of the membrane. In this study, the variation in water content collected at the outlet of a membrane humidifier is investigated with a one-dimensional mass exchanger model and various operating variables. The vapor concentration of outlet flows is affected by operating temperature and relative humidity of the membrane humidifier. Relative humidity of the dry side at the point of outlet flow, to be supplied to the fuel cell module, is the key characteristic. The analogy of the effectiveness-NTU approach for heat transfer is used to analyze the characteristics of the mass exchanger. Mass flux through the membranes is estimated with an overall mass transfer coefficient which represents vapor transport characteristics moving through the membrane module. This coefficient has a similar role to the overall heat transfer coefficient in heat exchanger analysis. This parametric study is conducted to understand the effects of different variables. The Effectiveness-NTU methodology of mass transfer uses the overall mass transfer coefficient and the mass transfer rate, as evaluated experimentally. Simulink software is then employed to deliver outcomes of the model for different operating conditions.

Influence of Gas-Liquid Distribution Inducer on Mass Transfer Coefficient in Rotating Packed Bed

2014 ◽  
Vol 908 ◽  
pp. 277-281
Author(s):  
Fei Wu ◽  
Jie Wu ◽  
Mei Jin ◽  
Fang Wang ◽  
Ping Lu
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Flow Rate ◽  
Rotor Blade ◽  
Gas Flow ◽  
Packed Bed ◽  
Contact Length ◽  
Liquid Distribution ◽  
Rotating Packed Bed

Based on acetone-H2O system, the influence of the gas-liquid distribution inducer on the mass transfer coefficient in the rotating packed bed with the stainless steel packing was investigated. Furthermore, the absorption performance was also obtained under the experimental condition of the rotational speed of 630 rpm, the gas flow rate of 2 m3/h and the liquid flow rate of 100 L/h in the rotating packed bed with different types and different installation ways of the distribution inducer. The experimental results showed that the volumetric mass transfer coefficient Kyα per unit contact length of gas-liquid was increased by 8.6% for the forward-curved fixed blade, by 19.8% for the backward-curved rotor blade and by 33.2% with the combination of the straight radial rotor blade and the backward-curved fixed blade, respectively. Furthermore, when the gas flow rate was 2.5 m3/h, Kyα per unit contact length of gas-liquid was increased by 2.9% for the forward-curved fixed blade, by 25.3% for the backward-curved rotor blade, by 42.7% for the combination of the straight radial rotor blade and the backward-curved fixed blade, respectively. The results indicated that the distribution inducer play an important role on the improvement of the mass transfer coefficient in acetone-H2O system.

scholarly journals Overall Mass Transfer Coefficient of CO2 Absorption in a Diameter-varying Spray Tower

2017 ◽  
Vol 114 ◽  
pp. 1665-1670 ◽  
Author(s):  
Xiaomei Wu ◽  
Min He ◽  
Yunsong Yu ◽  
Zhen Qin ◽  
Zaoxiao Zhang
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Co2 Absorption ◽  
Spray Tower ◽  
Overall Mass Transfer Coefficient

scholarly journals TOTAL VOLUMETRIC MASS TRANSFER COEFFICIENT AT CO2 GAS ABSORPTION USING K2CO3 BY MSG PROMOTER

Konversi ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 6
Author(s):  
Erlinda Ningsih ◽  
Abas Sato ◽  
Mochammad Alfan Nafiuddin ◽  
Wisnu Setyo Putranto
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Flow Rate ◽  
Liquid Flow ◽  
Total Mass ◽  
Gas Flow ◽  
Liquid Flow Rate ◽  
Gas Flow Rate ◽  
Co2 Gas

Abstract- One of the most widely used processes for CO2 gas removal is Absorption. Carbon dioxide is the result of the fuel combustion process which of the hazardous gases. The aim of this research is to determine the total mass transfer coefficient and analyze the effect of the absorbent flow rate of the absorbent solution with the promoter and the gas flow rate to the total mass transfer coefficient value. The variables consisted of liquid flow rate: 1, 2, 3, 4, 5 liter/min, gas flow rate: 15, 25, 30, 40, 50 liter/min and MSG concentration: 0%, 1%, 3% and 5% by weight. The solution of Pottasium Carbonate as absorbent with MSG promoter is flowed through top column and CO2 gas flowed from bottom packed column. Liquids were analyzed by titration and the gas output was analyzed by GC. From this research, it is found that the flow rate of gas and the liquid flow rate is directly proportional to the value of KGa. The liquid flow rate variable 5 liters / minute, gas flow rate 15 l / min obtained value of KGa 11,1102 at concentration of MSG 5%. Keywords:  Absorption, CO2,  K2CO3, MSG. 

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