Analytical Study of Heat and Mass Transfer in Porous Sheets During Contact Drying Process

2008 ◽  
Author(s):  
Mohammad R. Izadpanah ◽  
Amir R. Ansari Dezfooli
Keyword(s):  
Mass Transfer ◽  
Temperature Distribution ◽  
Moisture Content ◽  
Close Agreement ◽  
Analytical Study ◽  
Numerical Data ◽  
Drying Process ◽  
Governing Equations ◽  
Sturm Liouville ◽  
Contact Drying

Contact drying process has gained wide application in different industries including paper, ceramics and construction industries. Suitable control over temperature distribution will result in required moisture content and its distribution. In the present study, governing equations for a porous sheet are derived using Luikov equation. These equations are then converted into sturm-liouville equations and solved simultaneously. Comparison of temperature and moisture distributions with numerical data shows a close agreement.

Heat and Mass Transfer during Contact Drying in a Laundry Calender

1973 ◽  
Vol 187 (1) ◽  
pp. 591-599
Author(s):  
J. F. T. MacLaren ◽  
A. A. Nicol ◽  
R. Wallace
Keyword(s):  
Mass Transfer ◽  
Moisture Content ◽  
Heat And Mass Transfer ◽  
Initial Moisture Content ◽  
Temperature Profiles ◽  
Drying Process ◽  
Steam Temperature ◽  
Empirical Expression ◽  
Contact Drying ◽  
Physical Variables

Contact drying of fabric was studied using a two-roll steam-heated laundry calender. The effects on heat and mass transfer of steam temperature, fabric initial moisture content, fabric velocity, contact pressure and steam-side heat transfer coefficient were observed experimentally. Bed and roller surface temperature profiles were measured to assist in interpreting and subsequently analysing the drying process. The experimental results were correlated using dimensionless parameters derived from a dimensional analysis of a drying equation. An empirical expression was obtained that related the final moisture content of the fabric to the initial moisture content and the other pertinent physical variables.

Heat and Mass Transfer during Contact Drying in a Laundry Calender

1973 ◽  
Vol 187 (1) ◽  
pp. 591-599
Author(s):  
J. F. T. MacLaren ◽  
A. A. Nicol ◽  
R. Wallace
Keyword(s):  
Mass Transfer ◽  
Moisture Content ◽  
Heat And Mass Transfer ◽  
Initial Moisture Content ◽  
Temperature Profiles ◽  
Drying Process ◽  
Steam Temperature ◽  
Empirical Expression ◽  
Contact Drying ◽  
Physical Variables

Contact drying of fabric was studied using a two-roll steam-heated laundry calender. The effects on heat and mass transfer of steam temperature, fabric initial moisture content, fabric velocity, contact pressure and steam-side heat transfer coefficient were observed experimentally. Bed and roller surface temperature profiles were measured to assist in interpreting and subsequently analysing the drying process. The experimental results were correlated using dimensionless parameters derived from a dimensional analysis of a drying equation. An empirical expression was obtained that related the final moisture content of the fabric to the initial moisture content and the other pertinent physical variables.

Heat and Mass Transfer during Drying of Clay Ceramic Materials: A Three-Dimensional Analytical Study

2017 ◽  
Vol 10 ◽  
pp. 93-106 ◽  
Author(s):  
M.K. Teixeira de Brito ◽  
D.B. Teixeira de Almeida ◽  
A.G. Barbosa de Lima ◽  
L. Almeida Rocha ◽  
E. Santana de Lima ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Analytical Study ◽  
Separation Of Variables ◽  
Three Dimensional ◽  
Ceramic Materials ◽  
Governing Equations ◽  
Convective Boundary ◽  
Good Agreement

This work aims to study heat and mass transfer in solids with parallelepiped shape with particular reference to drying process. A transient three-dimensional mathematical model based on the Fick ́s and Fourier ́s Laws was developed to predict heat and mass transport in solids considering constant physical properties and convective boundary conditions at the surface of the solid. The analytical solution of the governing equations was obtained using the method of separation of variables. The study was applied in the drying of common ceramic bricks. Predicted results of the heating and drying kinetics and the moisture and temperature distributions inside the material during the process, are compared with experimental data and good agreement was obtained. It has been found that the vertices of the solid dry and heat first. This provokes thermal and hydric stresses inside the material, which may compromise the quality of the product after drying.

scholarly journals Simulation and Analysis of Plug Flow Fluidized Bed Dryer

2020 ◽  
Vol 9 (7) ◽  
pp. 805-811
Keyword(s):  
Mass Transfer ◽  
Moisture Content ◽  
Heat And Mass Transfer ◽  
Fluidized Bed ◽  
Plug Flow ◽  
Small Scale ◽  
Outlet Temperature ◽  
Drying Process ◽  
Fluidized Bed Dryer ◽  
Hot Air

Today many industries now use the dryer as a part of grain-drying process even during wet and dry seasons. This helps in reducing spoilage and wastage of paddy. Mostly the available industrial dryers are expensive to purchase and to maintain its smooth functioning. This study therefore is a step to design a simple Plug flow fluidized dryer that can lead to introduce small scale dryers to paddy process industry. The Plug flow fluidized bed dryers are designed and fabricated in this study consists of the drying chamber, hot air distributer plate, hot air inlet and exit system, paddy entry and exit system, fluidization chamber unit with temperature control unit and the centrifugal fan. The evaluation of dryer is based on drying time and reduction in moisture content and outlet temperature of paddy on quality parameters. Dryer dimensions are very important to analyze heat and mass transfer analysis of the Plug flow fluidized bed drying process of paddy grains. It was found d that heat and mass transfer properties of paddy grains in fluidized bed dryer was decreases as the time of drying passes and very rapid at the start of drying. The model present here predicts about dryer dimensions along safe zone of rough rice moisture content with other parameters. Simulation results show a good agreement between the simulation model and the existing simulation models

scholarly journals Mass transfer effects on an unsteady MHD free convective flow of an incompressible viscous dissipative fluid past an infinite vertical porous plate

2016 ◽  
Vol 21 (1) ◽  
pp. 143-155 ◽  
Author(s):  
B. Prabhakar Reddy
Keyword(s):  
Mass Transfer ◽  
Porous Plate ◽  
Numerical Data ◽  
Convection Flow ◽  
Governing Equations ◽  
Transfer Effects ◽  
Electrically Conducting ◽  
Vertical Porous Plate ◽  
Flow Parameters ◽  
Dissipative Fluid

Abstract In this paper, a numerical solution of mass transfer effects on an unsteady free convection flow of an incompressible electrically conducting viscous dissipative fluid past an infinite vertical porous plate under the influence of a uniform magnetic field considered normal to the plate has been obtained. The non-dimensional governing equations for this investigation are solved numerically by using the Ritz finite element method. The effects of flow parameters on the velocity, temperature and concentration fields are presented through the graphs and numerical data for the skin-friction, Nusselt and Sherwood numbers are presented in tables and then discussed.

Mass Transfer in Irregularly-Shaped Solid: An Exact Solution Using the Galerkin-Based Integral Method

2012 ◽  
Vol 326-328 ◽  
pp. 199-204 ◽  
Author(s):  
I. Batista dos Santos ◽  
L.P. de Lucena Silva ◽  
Antônio Gilson Barbosa de Lima
Keyword(s):  
Mass Transfer ◽  
Moisture Content ◽  
Biot Number ◽  
Integral Method ◽  
Arbitrary Shape ◽  
Convective Boundary Condition ◽  
Drying Process ◽  
Convective Boundary ◽  
Liquid Diffusion ◽  
The Mean

This paper presents a theoretical investigation of the mass transfer during the drying of solids of revolution with arbitrary shape. A two-dimensional mathematical model by assuming the liquid diffusion to be the sole mechanism of moisture transport, constant thermophysical properties and convective boundary condition at the surface of the solid is presented. The resulting equation is solved analytically by using the Galerkin-based integral method. Results of the mean moisture content and moisture content distribution within the porous solid are present and analyzed during the process, for different Biot number and aspect ratio. We conclude that solid drying rate is affected by Biot number and area/volume relationships, and which drying process is faster in sharp areas and closed to surface of the solid.

Forced Convective Drying of a Porous Cube: Non-Intrusive Temperature and Mass Transfer Measurements

2014 ◽  
Author(s):  
Eoin Fanning ◽  
Tim Persoons ◽  
Darina B. Murray
Keyword(s):  
Mass Transfer ◽  
Temperature Distribution ◽  
Moisture Content ◽  
Surface Temperature ◽  
Convective Drying ◽  
Drying Rate ◽  
Local Surface ◽  
Number Range ◽  
Rate Period ◽  
Local Surface Temperature

The evolution of the mass transfer rate and temperature of a porous body in a convective drying process shows two main stages: A constant-drying rate period and a falling-drying rate period. This study investigates the simultaneous time evolution of moisture content and local surface temperature of a porous cube inside a rectangular flow channel for a range of air flow temperatures and Reynolds numbers. The moisture content is measured using a precision mass balance. Local surface temperature distribution is measured using a thermal imaging camera. In the constant-drying rate period, an average Nusselt number in the range 7.1 ≤ Nu ≤ 13.3 and an average Sherwood number of 4.7 ≤ Sh ≤ 6.0 are calculated for a Reynolds number range of 180 ≤ Re ≤ 595. Infrared thermography shows that the falling-drying rate period begins, the temperature distribution becomes non-uniform and approaches the temperature of the surroundings. This transition occurs first near the edges of the cube and, in particular, near the leading edge of the cube, as witnessed in previous studies.

Drying (Consolidation) Porous Ceramic by Considering the Microscopic Pore Temperature Gradient

2011 ◽  
Vol 147 ◽  
pp. 210-214 ◽  
Author(s):  
Zawati Harun ◽  
David Gethin
Keyword(s):  
Mass Transfer ◽  
Temperature Gradient ◽  
Porous Ceramic ◽  
Convective Drying ◽  
Comprehensive Model ◽  
Two Dimensional ◽  
Drying Process ◽  
Governing Equations ◽  
Fully Coupled ◽  
Good Agreement

In this work, a two-dimensional numerical model of heat and mass transfer for the convective drying process of ceramic material was developed. The governing equations of fully coupled non-linear partial differential was derived from the most comprehensive model with considering the heat, moisture and gas transport along with the influence of microscopic pore temperature gradient. Through validation the distribution of the measured variables and coefficients (diffusivity) show a good agreement with the drying stage in porous material.

scholarly journals A Numerical Implementation of the Soret Effect in Drying Processes

2020 ◽  
Vol 4 (1) ◽  
pp. 13
Author(s):  
Bartolomeus Häussling Löwgren ◽  
Julius Bergmann ◽  
Odilio Alves-Filho
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Soret Effect ◽  
Numerical Approach ◽  
Transport Mechanisms ◽  
Drying Process ◽  
Governing Equations ◽  
Transfer Equations ◽  
Gradient Effects ◽  
Dynamic Heating

Drying of porous media is strictly governed by heat and mass transfer. However, contrary to the definition that drying is simultaneous transport mechanisms of heat and mass, most past and current models either account for temperature or concentration gradient effects on drying. Even though the complexity of computations of these processes varies with area of application, in most cases, the Dufour and Soret effects are neglected. This leads to deviations and uncertainties on the assumptions and interpretations of these and other relevant effects on drying. This paper covers the theoretical methods to derive the coupled transfer effects. In addition, this work proposes and formulates relevant heat and mass transfer equations, as well as the governing equations for drying processes with Dufour and Soret effects. The application of a numerical approach to solve the equations allows for studying of the influence of these effects on the design and operation of dryers. It is shown that the Soret effect can be highly relevant on drying operations with dynamic heating operation. While for drying processes where the steady state drying process predominates, the effect is deemed negligible.

On the Modeling of Drying Process in an Industrial Tunnel Dryer

2020 ◽  
Vol 400 ◽  
pp. 51-56
Author(s):  
Francisca Valdeiza de Souza Tavares ◽  
Atacy Maciel de Melo Cavalcante ◽  
Maria José de Figueiredo ◽  
Anderson Ferreira Vilela ◽  
Ana Raquel Carmo de Lima ◽  
...  
Keyword(s):  
Moisture Content ◽  
Mass Conservation ◽  
Convective Drying ◽  
Average Moisture Content ◽  
Drying Process ◽  
Governing Equations ◽  
Tunnel Dryer ◽  
Good Concordance ◽  
Volume Method ◽  
Hollow Bricks

This paper aims to study convective drying of industrial hollow bricks in a tunnel dryer. A transient mathematical model based on the heat and mass conservation equations applied to the air and brick was derived and the numerical solution (finite-volume method) of the governing equations is presented. Predicted and experimental data of the average moisture content and the temperature of the product during the drying process are compared and a good concordance was verified. Numerical results inside the bed confirm an almost null difference between the moisture content along the process. Similar behavior was verified to the product temperature. These results confirm an efficient drying process.

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