scholarly journals Numerical Study of Heat and Mass Transfer during the Evaporative Drying of Porous Media

2020 ◽  
Vol 307 ◽  
pp. 01050
Author(s):  
Karima SELLAMI ◽  
M’barek FEDDAOUI ◽  
Nabila LABSI ◽  
M’hand OUBELLA ◽  
Youb Khaled BENKAHLA
Keyword(s):  
Porous Media ◽  
Layer Thickness ◽  
Porous Layer ◽  
Mass Flow ◽  
Numerical Study ◽  
Vertical Channel ◽  
Drying Rate ◽  
Gas Temperature ◽  
Drying Process ◽  
Simpler Algorithm

The paper deals with numerical study of drying process of porous media of sand during the evaporation of a liquid saturated porous layer within parallel vertical channel. The liquid and air streams are modeled as two coupled laminar boundary layers incorporating non-Darcian models of the inertia and boundary effects. The governing equations and the associated boundary conditions are discretized by means of the finite volume method implemented on a staggered mesh and the velocity-pressure coupling is processed by the SIMPLER algorithm. The influences of the inlet mass flow of the drying gas, porous layer thickness and the porosity on the drying process are analyzed. Results show that the drying rate of the porous media is improved by the reduction of the porosity and porous layer thickness a large drying rate is obtained with high inlet mass flow and high inlet gas temperature.

Analysis of entropy generation and natural convection in an inclined partially porous layered cavity filled with a nanofluid

2017 ◽  
Vol 95 (3) ◽  
pp. 238-252 ◽  
Author(s):  
T. Armaghani ◽  
Muneer A. Ismael ◽  
Ali J. Chamkha
Keyword(s):  
Natural Convection ◽  
Rayleigh Number ◽  
Layer Thickness ◽  
Porous Layer ◽  
Entropy Generation ◽  
Thermal Performance ◽  
Volume Fraction ◽  
Numerical Study ◽  
Nanoparticle Volume Fraction ◽  
Thermodynamic Irreversibility

The present numerical study investigates the analysis of thermodynamic irreversibility generation and the natural convection in inclined partially porous layered cavity filled with a Cu–water nanofluid. The finite difference method with up-wind scheme is used to solve the governing equations. The study is achieved by examining the effects of nanoparticle volume fraction, inclination angle, and the porous layer thickness. Besides, the computations are achieved within the laminar range of the Rayleigh number. The results show that at Ra = 104, a reduction of total entropy generation is recorded with increasing nanoparticle volume fraction when the porous layer thickness is greater than 0.2. Moreover, when Ra is less than 105, the nanoparticle volume fraction increases the heat transfer irreversibility, and improves the overall thermal performance. It is found also that for a low Rayleigh number, the largest porous layer thickness and the highest cavity orientation improve the thermal performance. On the contrary, at high Rayleigh numbers, these parameter ranges give the worst thermal performance.

Modification of rotary air preheater toward achieving extended life-span utilizing porous media approach: A case study

2021 ◽  
pp. 095765092110349
Author(s):  
Hamed Hajebzadeh ◽  
Abdulhamid NM Ansari
Keyword(s):  
Porous Media ◽  
Power Plant ◽  
Relative Error ◽  
Mass Flow ◽  
Cfd Simulation ◽  
Maximum Relative Error ◽  
Gas Temperature ◽  
Operational Parameters ◽  
Operating Life ◽  
Porous Media Model

The main goal of this study is to achieve the extended operating life of the rotary regenerative air pre-heater (Ljungström) of Bandar Abbas power plant by modifying operational parameters by decreasing the corrosion. To achieve this goal, a three-dimensional CFD simulation of the Ljungström is carried out, utilizing the thermal non-equilibrium porous media model. Temperatures are validated against measured data from the power plant with a maximum relative error of 5.54% on the Celsius scale, and mass flow rates are validated with a maximum relative error of −5.25%. The effect of the Ljungström key parameters including the rotational speed, cold layer material, inlet air/flue gas temperature, and mass flow rate, are analyzed in presence of leakages and neglecting it, using porous media approach. The leakage effect is investigated considering radial and axial/peripheral clearances. Finally, a simulation is performed by applying feasible improved parameters extracted from the above analyses considering the effect of all parameters together in presence of leakages, which shows a 6.14% improvement in the Ljungström effectiveness, reducing the total leakage to about one-third of the actual model and eliminating any corrosion.

From red cells to soft lubrication, an experimental study of lift generation inside a compressible porous layer

2017 ◽  
Vol 818 ◽  
pp. 5-25 ◽  
Author(s):  
T. Gacka ◽  
Z. Zhu ◽  
R. Crawford ◽  
R. Nathan ◽  
Q. Wu
Keyword(s):  
Experimental Study ◽  
Porous Media ◽  
Pore Pressure ◽  
Layer Thickness ◽  
Porous Layer ◽  
Endothelial Glycocalyx ◽  
Porous Media Flow ◽  
Pressure Transducers ◽  
Porous Sheet ◽  
Trailing Edges

It is a new concept for porous media flow that a hydrodynamic lifting force is generated inside a highly compressible porous layer as a planing surface glides over it. The concept originated from the observation of the pop-out phenomena of red blood cells over the endothelial glycocalyx layer (EGL) lining the inner surface of our blood vessels (Feng & Weinbaum, J. Fluid Mech., vol. 422, 2000, pp. 282–317). In the current paper, we report an experimental study to examine this concept. A novel testing set-up was developed that consists of a running conveyer belt covered with a soft porous sheet, and a fully instrumented upper planar board, i.e. planing surface. The generation of pore pressure was observed and captured by pressure transducers when the planing surface glides over the porous sheet. Its distribution strongly depends on the relative velocity between the planing surface and the running belt, the mechanical and transport properties of the porous sheet as well as the compression ratios at the leading and trailing edges. The relative contribution of the transiently trapped air to the total lift was evaluated by comparing the pore pressure to the total lifting pressure measured by a load cell mounted between two adjacent pressure transducers. For a typical running condition with a polyester porous material ($k=h_{2}/h_{1}=5$, $\unicode[STIX]{x1D706}=h_{2}/h_{0}=1$, $U=3.8~\text{m}~\text{s}^{-1}$, where $h_{2}$, $h_{1}$, are the porous layer thickness at the leading and trailing edges, respectively; $h_{0}$ is the un-deformed porous layer thickness; and $U$ is the velocity of the running belt), over 68 % of the local lift is generated by the pore pressure. The results conclusively verified the validity of lift generation in a highly compressible porous layer as a planing surface glides over it. This study provides the foundation for the application of highly compressible porous media for soft lubrication with minimal frictional losses. It also sheds some light on the biophysics study of the EGL.

Enhancement of Drying Rate of Moist Porous Media With Electrohydrodynamically Assisted Slot Jet Reattachment Nozzle: A Numerical Study

2019 ◽  
Author(s):  
Mengqiao Yang ◽  
Jamal Yagoobi ◽  
Burt Tilley
Keyword(s):  
Mass Transfer ◽  
Porous Media ◽  
Heat And Mass Transfer ◽  
Numerical Study ◽  
Convective Drying ◽  
Drying Rate ◽  
Ionic Wind ◽  
Coupled Flow ◽  
Simulation Results ◽  
Moist Porous Material

Abstract Drying of moist porous media, such as food or pulp and paper, is an energy-intensive process. Innovative impinging jet nozzles, for instance, radial jet reattachment (RJR) and slot jet reattachment (SJR) nozzles, have been proved to be one of the efficient methods to enhance the drying rate compared to traditional in-line jet and slot jet nozzles. However, the heat and mass transfer in the region immediately underneath these nozzles are relatively inefficient. In this work, the performance of the SJR nozzle is improved by the application of electrical field, specifically, ionic wind generated in the region directly between the nozzle exit and the exposed surface of moist porous material. The numerical model is based on the coupled flow field generated by electrohydrodynamically (EHD) assisted SJR nozzle with the heat and mass transfer taking place within the moist porous media during the drying process. The simulation results show a significant secondary flow induced under the nozzle due to the ionic wind. Up to 40% drying rate enhancement has been achieved. However, the enhancement of drying rate diminishes as the air exit velocity exceeds a certain threshold. The simulation results illustrate the detailed fundamental understanding of this conjugated problem and provide a foundation for the enhancement of convective drying of moist porous materials.

scholarly journals Experimental Investigations on Drying of Porous Media Using Infrared Radiation

10.14311/196 ◽  
2001 ◽  
Vol 41 (1) ◽  
Author(s):  
A. K. Haghi
Keyword(s):  
Porous Media ◽  
Image Analysis ◽  
Infrared Radiation ◽  
Experimental Investigations ◽  
Drying Rate ◽  
Drying Process ◽  
Infrared Drying

Increased interest is being shown in infrared drying today because of the environmental and technological advantages offered by this method. In order to assess the advantages of this drying process, extensive trials have been carried out. The objective of this investigation was to study the drying rate of infrared drying. This was achieved with the use of scanning pyrometer and image analysis. 

NUMERICAL STUDY OF POROUS MEDIA TURBULENT COMBUSTION IN A RECUPERATIVE REACTOR

2016 ◽  
Vol 19 (11) ◽  
pp. 941-953 ◽  
Author(s):  
Pablo Donoso-Garcia ◽  
Luis Henriquez-Vargas
Keyword(s):  
Porous Media ◽  
Turbulent Combustion ◽  
Numerical Study

CATFISH DRYING (Clarias Batraclus) USING ‘TEKO BERSAYAP’ SOLAR DRYER

2012 ◽  
Vol 2 (1) ◽  
pp. 14-20
Author(s):  
Yuwana Yuwana
Keyword(s):  
Relative Humidity ◽  
Moisture Content ◽  
Ambient Temperature ◽  
Drying Rate ◽  
Drying Process ◽  
Drying Time ◽  
Ambient Relative Humidity ◽  
Solar Dryer

Experiment on catfish drying employing ‘Teko Bersayap’ solar dryer was conducted. The result of the experiment indicated that the dryer was able to increase ambient temperature up to 44% and decrease ambient relative humidity up to 103%. Fish drying process followed equations : KAu = 74,94 e-0,03t for unsplitted fish and KAb = 79,25 e-0,09t for splitted fish, where KAu = moisture content of unsplitted fish (%), KAb = moisture content of splitted fish (%), t = drying time. Drying of unsplitted fish finished in 43.995 hours while drying of split fish completed in 15.29 hours. Splitting the fish increased 2,877 times drying rate.

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