scholarly journals Experimental Study of Heat and Mass Transfer for Liquid Film Evaporation along a Vertical Plate Covered With a Porous Layer

2016 ◽  
Vol 9 (SI1) ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Monssif Najim ◽  
M’barek Feddaoui ◽  
Abderrahman Nait Alla ◽  
Adil Charef

A numerical study of mixed convection heat and mass transfer along a vertical channel with a wavy wall is performed. The wavy wall is heated by a constant flux, while the other is adiabatic. The discretisation of equations in both liquid and gas phases is realised using an implicit finite difference scheme. Results of simulation compare the effect of multiple parameters, especially amplitude and characteristic length of the curve, on the liquid film evaporation process. The results indicate that heat and mass transfer is enhanced by increasing the amplitude and number of wall waves. Moreover, a very small value of waves amplitude of the wall may reduce the sensible heat and mass transfer.


Author(s):  
Md Hasanuzzaman

In this paper, heat and mass transfer for liquid evaporation along a vertical plate covered with a thin porous layer has been investigated. The continuity, momentum, energy and mass balance equations, which are coupled nonlinear partial differential equations are reduced to a set of two nonlinear ordinary differential equations and solved analytically and numerically by using the shooting technique in MATLAB. The effect of various parameters like the Froude number, the porosity, the Darcy number, the Prandtl number, the Lewis number and the driving parameters on the temperature and concentration profiles are presented and discussed. It is viewed that the heat transfer performance is enhanced by the presence of a porous layer. The local Nusselt number and the local Sherwood numbers are computed and analyzed both numerically and graphically.


Author(s):  
Monssif Najim ◽  
M'barek Feddaoui ◽  
Abderrahman Nait Alla ◽  
Adil Charef

This chapter presents a numerical investigation of heat and mass transfer characteristics during the evaporation of liquid films in vertical geometries. A two-phase model is developed to simulate laminar film evaporation into laminar gas flow. The liquid film evaporation is evaluated under adiabatic and heated wall conditions for both pure and binary liquid film. The model is based on a finite difference method to solve the governing equations of the two phases. The obtained results concerns two industrial processes. The first part of the chapter is devoted to the analysis of the thermal protection of vertical channel wall, while the second part is devoted to the desalination process by falling liquid film. The simulations results allowed the determination of the optimal operating conditions for both processes.


2015 ◽  
Vol 19 (5) ◽  
pp. 1805-1819 ◽  
Author(s):  
M’hand Oubella ◽  
M’barek Feddaoui ◽  
Rachid Mir

A numerical study of mixed convection heat and mass transfer with film evaporation in a vertical channel is developed. The emphasis is focused on the effects of vaporization of three different liquid films having widely different properties, along the isothermal and wetted walls on the heat and mass transfer rates in the channel. The induced laminar downward flow is a mixture of blowing dry air and vapour of water, methanol or acetone, assumed as ideal gases. A two-dimensional steady state and elliptical flow model, connected with variable thermo-physical properties, is used and the phase change problem is based on thin liquid film assumptions. The governing equations of the model are solved by a finite volume method and the velocity-pressure fields are linked by SIMPLE algorithm. The numerical results, including the velocity, temperature and concentration profiles, as well as axial variations of Nusselt numbers, Sherwood number and dimensionless film evaporation rate are presented for two values of inlet temperature and Reynolds number. It was found that lower the inlet temperature and Re, the higher the induced flows cooling with respect of most volatile film. The better mass transfer rates related with film evaporation are found for a system with low mass diffusion coefficient.


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