Numerical study on the effect of inert region on mass transfer by the segmented electrodes in limiting current method

1987 ◽  
Vol 4 (1) ◽  
pp. 67-72
Author(s):  
Woo Sik Kim ◽  
Joong Kon Park ◽  
Ho Nam Chang
Keyword(s):  
Mass Transfer ◽  
Numerical Study ◽  
Current Method ◽  
Limiting Current ◽  
Inert Region

Possibilities of the Use of the Electrolytic Technique for the Investigations of Mass/Heat Transfer in Nanofluid

2016 ◽  
Vol 831 ◽  
pp. 216-222 ◽  
Author(s):  
Sebastian Grosicki
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Current Method ◽  
Annular Channel ◽  
Ion Concentration ◽  
Limiting Current ◽  
Transfer Coefficients ◽  
Transfer Experiment ◽  
Heat Transfer Coefficients ◽  
Physical Phenomena

In the paper the author presents the possibilities of the application of the electrolytic technique for the investigation of heat transfer coefficients in channels with nanofluids. The electrolytic technique called the limiting current method enables to obtain mass transfer coefficients on the basis of the electrochemical processes and the laws governing these physical phenomena. The exemplary graph presenting the limiting currents values resulting from the experiment is shown in Fig. 1. These are the voltammograms at different Reynolds numbers and the ion concentration Cb. Heat transfer coefficients can be calculated using the correlations describing the analogy of mass and heat transfer processes. Some cases of the possible application of the electrolytic technique and factors influencing the mass transfer experiment including the state of the electroactive surface, change in ion concentration and thickness of the diffusion layer are discussed in [1]. In this work the author focused on the mass transfer experiment with the application of the nanofluid. Special properties of the nanofluid should be taken into account in the investigations. The paper presents the preliminary results of the experiment with nanofluid in the annular channel.

A review of electrocoagulation technology for the treatment of textile wastewater

2017 ◽  
Vol 33 (3) ◽  
Author(s):  
Ahmed Samir Naje ◽  
Shreeshivadasan Chelliapan ◽  
Zuriati Zakaria ◽  
Mohammed A. Ajeel ◽  
Peter Adeniyi Alaba
Keyword(s):  
Mass Transfer ◽  
Removal Rate ◽  
Cell Mass ◽  
Current Method ◽  
Textile Wastewater ◽  
Electrical Energy ◽  
Limiting Current ◽  
Dynamics Modeling ◽  
Operational Parameters ◽  
Active Metal

AbstractThe conventional coagulation technique of textile wastewater treatments is plagued with the issue of low removal rate of pollutants and generation of a large quantity of sludge. Recently, electrocoagulation (EC) technique gained immense attention due to its efficiency. The technique involves dissolution of the sacrificial anodes to provide an active metal hydroxide as a strong coagulant that destabilizes and amasses particles and then removes them by precipitation or adsorption. EC process is influenced by operating parameters such as applied current density, electrodes material and configuration, type of electrical connection, pH and conductivity of the solution, and mixing state. Consequently, this work reviewed the major and minor reactions of EC process with operational parameters, design of EC cell, mass transfer studies and modeling, and industrial wastewater applications. The work also includes comparison of EC technique with conventional coagulation and combinations with other techniques. Special emphasis is on removal of pollutants from textile wastewater. Further, the electrical energy supplies and cost analysis are also discussed. Even though several publications have covered EC process recently, no review work has treated the systematic process design and how to minimize the effect of passivation layer deposited on the surface of the electrodes. EC process with rotating electrodes has been recommended to reduce this phenomenon. The effect of electrodes geometry is considered to enhance the conductivity of the cell and reduce energy consumption. The studies of ionic mass transfer were not implemented before special by limiting current method during the EC process. Moreover, no aforementioned studies used computational fluid dynamics modeling to present the mass transfer inside the EC reactor.

Numerical Study of the Combined Free-Forced Convection and Mass Transfer Flow Past a Vertical Porous Plate in a Porous Medium with Heat Generation and Thermal Diffusion

2006 ◽  
Vol 11 (4) ◽  
pp. 331-343 ◽  
Author(s):  
M. S. Alam ◽  
M. M. Rahman ◽  
M. A. Samad
Keyword(s):  
Mass Transfer ◽  
Flow Field ◽  
Differential Equations ◽  
Forced Convection ◽  
Heat Generation ◽  
Numerical Study ◽  
Porous Plate ◽  
Integration Scheme ◽  
Suction Parameter ◽  
Transfer Flow

The problem of combined free-forced convection and mass transfer flow over a vertical porous flat plate, in presence of heat generation and thermaldiffusion, is studied numerically. The non-linear partial differential equations and their boundary conditions, describing the problem under consideration, are transformed into a system of ordinary differential equations by using usual similarity transformations. This system is solved numerically by applying Nachtsheim-Swigert shooting iteration technique together with Runge-Kutta sixth order integration scheme. The effects of suction parameter, heat generation parameter and Soret number are examined on the flow field of a hydrogen-air mixture as a non-chemical reacting fluid pair. The analysis of the obtained results showed that the flow field is significantly influenced by these parameters.

scholarly journals Numerical Study of a Cooling System Using Phase Change of a Refrigerant in a Thermosyphon

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3634
Author(s):  
Grzegorz Czerwiński ◽  
Jerzy Wołoszyn
Keyword(s):  
Mass Transfer ◽  
Phase Change ◽  
Heat Dissipation ◽  
Cooling System ◽  
Numerical Study ◽  
Relaxation Parameter ◽  
Phase Changes ◽  
Transfer Time ◽  
Two Phase ◽  
Time Relaxation

With the increasing trend toward the miniaturization of electronic devices, the issue of heat dissipation becomes essential. The use of phase changes in a two-phase closed thermosyphon (TPCT) enables a significant reduction in the heat generated even at high temperatures. In this paper, we propose a modification of the evaporation–condensation model implemented in ANSYS Fluent. The modification was to manipulate the value of the mass transfer time relaxation parameter for evaporation and condensation. The developed model in the form of a UDF script allowed the introduction of additional source equations, and the obtained solution is compared with the results available in the literature. The variable value of the mass transfer time relaxation parameter during condensation rc depending on the density of the liquid and vapour phase was taken into account in the calculations. However, compared to previous numerical studies, more accurate modelling of the phase change phenomenon of the medium in the thermosyphon was possible by adopting a mass transfer time relaxation parameter during evaporation re = 1. The assumption of ten-fold higher values resulted in overestimated temperature values in all sections of the thermosyphon. Hence, the coefficient re should be selected individually depending on the case under study. A too large value may cause difficulties in obtaining the convergence of solutions, which, in the case of numerical grids with many elements (especially three-dimensional), significantly increases the computation time.

The heat/mass transfer to a finite strip at small Péclet numbers

1978 ◽  
Vol 86 (1) ◽  
pp. 49-65 ◽  
Author(s):  
R. C. Ackerberg ◽  
R. D. Patel ◽  
S. K. Gupta
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Shear Flow ◽  
Sodium Hydroxide Solution ◽  
Flow Direction ◽  
Mathematical Problem ◽  
Limiting Current ◽  
Transfer Rates ◽  
Uniform Shear ◽  
Uniform Shear Flow

The problem of heat transfer (or mass transfer at low transfer rates) to a strip of finite length in a uniform shear flow is considered. For small values of the Péclet number (based on wall shear rate and strip length), diffusion in the flow direction cannot be neglected as in the classical Leveque solution. The mathematical problem is solved by the method of matched asymptotic expansions and expressions for the local and overall dimensionless heat-transfer rate from the strip are found. Experimental data on wall mass-transfer rates in a tube at small Péclet numbers have been obtained by the well-known limiting-current method using potassium ferrocyanide and potassium ferricyanide in sodium hydroxide solution. The Schmidt number is large, so that a uniform shear flow can be assumed near the wall. Experimental results are compared with our theoretical predictions and the work of others, and the agreement is found to be excellent.

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