scholarly journals MATHEMATICAL MODELING OF WOOD DRYING PROCESS

2002 ◽  
Vol 7 (2) ◽  
pp. 177-190 ◽  
Author(s):  
R. Čiegis ◽  
V. Starikovičius
Keyword(s):  
Mathematical Modeling ◽  
Porous Medium ◽  
Moisture Transport ◽  
Phase System ◽  
Transport Mechanisms ◽  
Drying Process ◽  
Wood Drying ◽  
Moisture Movement ◽  
Flow Models ◽  
Three Phase

This work focuses on the development of mathematical models describing moisture movement in wood, when the wood is considered as porous medium. Main moisture transport mechanisms are discussed. It is shown how the wood can be described as a two‐ or three‐phase system. Summaries of several multiphase flow models are presented in the hierarchical order: from the most general models to more simple examples. The approximation steps are described explicitly, and all assumptions are given in detail. It shown how models for specific applications in wood drying or saturation can be obtained.

The Influence of Wood Specimen Surface Coating on Moisture Movement during Drying

Holzforschung ◽  
2002 ◽  
Vol 56 (5) ◽  
pp. 541-546 ◽  
Author(s):  
R. Baronas ◽  
F. Ivanauskas
Keyword(s):  
Surface Coating ◽  
Transverse Section ◽  
Wood Specimen ◽  
Two Dimensional ◽  
Drying Process ◽  
Dimensional Model ◽  
Wood Drying ◽  
Moisture Movement ◽  
One Dimensional ◽  
The One

Summary A model of wood drying under isothermal conditions taking into consideration coating of the surface of a specimen is presented in this paper in a two-dimensional formulation. The influence of the surface coating degree as well as geometrical shape of a wood specimen on the dynamics of drying is investigated. Exponentials, describing the dependence of the halfdrying time on the degree of coating of the edges, as well as on the ratio of the width to the thickness of the transverse section of specimens from the northern red oak (Quercus rubra), are presented for drying from above the fiber saturation point. This paper describes the conditions of usage of the two-dimensional moisture transfer model in contrast to the one-dimensional model for accurate prediction of the drying process taking into consideration the coating of edges of specimens having a rectangular transverse section. A measure of reliability of the one-dimensional model to predict the wood drying process of sawn boards is introduced in this paper.

THE FINITE DIFFERENCE SCHEME FOR MATHEMATICAL MODELING OF WOOD DRYING PROCESS

2001 ◽  
Vol 6 (1) ◽  
pp. 48-57 ◽  
Author(s):  
R. Čiegis ◽  
V. Starikovičius
Keyword(s):  
Mathematical Modeling ◽  
Finite Difference ◽  
Difference Scheme ◽  
Finite Difference Scheme ◽  
Stability And Convergence ◽  
Finite Difference Schemes ◽  
Drying Process ◽  
Moisture Movement ◽  
Different Types ◽  
The Stability

This work discusses issues on the design of finite difference schemes for modeling the moisture movement process in the wood. A new finite difference scheme is proposed. The stability and convergence in the maximum norm are proved for different types of boundary conditions.

scholarly journals PROBLEMATICS OF CONSTRUCTION OF MATHEMATICAL MODELS OF THE PROCESS OF MICROWAVE DRYING OF SOY

2019 ◽  
pp. 21-26
Author(s):  
Valentyna Bandura ◽  
Oleksandr Popiak
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Model ◽  
Raw Materials ◽  
Microwave Energy ◽  
Raw Material ◽  
Microwave Drying ◽  
Drying Methods ◽  
Soybean Seeds ◽  
Drying Process ◽  
Moisture Movement

The article reviews various techniques for mathematical modeling of the soybean drying process. The purpose of this paper is to review, analyze and compare existing approaches to mathematically describe the processes of moisture movement during microwave drying of soybeans. The only way to provide mathematical modeling of the processes occurring in the soybean grain is a combination of the transformation of microwave energy into heat, the heating of dipole water molecules existing in the seed, the processes of moving moisture from the center to the grain shell and evaporation of moisture. Today, microwave drying is one of the promising areas for research, because this method is much more efficient than traditional post-harvest grain drying methods and, at the same time, poorly understood. Factors on which the process of microwave drying depends on are the speed of movement of moisture in the micropores of the product, the initial temperature and humidity of the raw material, the placement of the main magnetron relative to the object of drying and the speed of movement of raw materials in the drying chamber. The object of the study in this article was to simplify the mathematical model of soybean seeds. To intensify the process of microwave drying, it is advisable to use a combined effect, such as blowing, which increases the intensity and quality of the process of microwave dehumidification. In addition, in this case, the simultaneous use of two or more factors of influence, which allows for rapid processing of raw materials. This determines the relevance and prospects of this study. The developed criteria criterion is substantiated and described, which allows to simplify the complex calculation of microwave energy transfer processes, sample heating and moisture velocity in it. The basic approaches to the construction of a mathematical model of the soybean drying process are considered, and their expediency is determined. The analysis of various methods of mathematical description of the drying process is carried out, the main disadvantages of these methods are identified. It is established that drying soybean seeds in the microwave field is one of the most promising. A mathematical model for a combined soybean drying process with a combination of microwave drying methods and air blowing is proposed.

scholarly journals Hardware for classification of power quality problems in three phase system using Microcontroller

2017 ◽  
Vol 4 (1) ◽  
pp. 1386364 ◽  
Author(s):  
S. Asha Kiranmai ◽  
A. Jaya Laxmi ◽  
Qingsong Ai
Keyword(s):  
Power Quality ◽  
Phase System ◽  
Three Phase

Activity coefficients, densities, dipole moments, and surface tensions of the system triethylamine–methylethylketone–water

1981 ◽  
Vol 59 (1) ◽  
pp. 127-131 ◽  
Author(s):  
Alan N. Campbell
Keyword(s):  
Surface Layer ◽  
Dipole Moments ◽  
Phase System ◽  
Constant Composition ◽  
Two Phase ◽  
Three Phase ◽  
Wide Range ◽  
Isothermal System ◽  
Total Composition ◽  
Two Phases

The properties named in the title have been determined by standard methods. Viscosity, molar volume, and orientation polarisation all indicate abnormalities of the nature of association between the components.The most interesting result is that of surface tension which indicates that, in the case of the binary system triethylamine–water, a surface layer of constant composition is formed over a wide range of total composition. When, by a rise in temperature of two or three degrees, this layer becomes unstable, it splits into two phases of different composition. The surface layer may then be instantaneously reformed and so on. A mechanism for the generation of a two-phase system is thus established. The data for the three-phase, isothermal, system are not so convincing, for reasons that are suggested.

scholarly journals Freeze-drying microscopy in mathematical modeling of a biomaterial freeze-drying

2012 ◽  
Vol 48 (2) ◽  
pp. 203-209 ◽  
Author(s):  
Camila Figueiredo Borgognoni ◽  
Joyce da Silva Bevilacqua ◽  
Ronaldo Nogueira de Moraes Pitombo
Keyword(s):  
Mathematical Modeling ◽  
Freeze Drying ◽  
Drying Process ◽  
Critical Temperatures ◽  
Fundamental Properties ◽  
Moving Interface ◽  
Energy Consuming ◽  
Sublimation Rates ◽  
Time And Energy

Transplantation brings hope for many patients. A multidisciplinary approach on this field aims at creating biologically functional tissues to be used as implants and prostheses. The freeze-drying process allows the fundamental properties of these materials to be preserved, making future manipulation and storage easier. Optimizing a freeze-drying cycle is of great importance since it aims at reducing process costs while increasing product quality of this time-and-energy-consuming process. Mathematical modeling comes as a tool to help a better understanding of the process variables behavior and consequently it helps optimization studies. Freeze-drying microscopy is a technique usually applied to determine critical temperatures of liquid formulations. It has been used in this work to determine the sublimation rates of a biological tissue freeze-drying. The sublimation rates were measured from the speed of the moving interface between the dried and the frozen layer under 21.33, 42.66 and 63.99 Pa. The studied variables were used in a theoretical model to simulate various temperature profiles of the freeze-drying process. Good agreement between the experimental and the simulated results was found.

Sign in / Sign up

Export Citation Format

Share Document