The use of cellular automata in modeling the processes of wood drying in a stack

In this work, we investigated the possibilities of using a model of cellular automata in solving the problem of heat and moisture transfer in a periodic wood drying chamber. Thus, in this work are investigating the processes of heat and moisture transfer between the wood and its drying agent. Studies are carried out by using CAD model of stack of dried wood. To use cellular automata, it is proposed to present the CAD model as an array of cubes, each of which has six faces (cells). In this work also proposes to use the different research zones, each of which allows us to calculate the values of temperature and moisture content in different places of the CAD model. In particular, these zones can be placed inside the wood, on its boundary or in the agent of its drying. The proposed cell-automata model contains local relationships between cells that describe their general behavior. In addition to describing the general behavior of cells, the model provides the possibility of setting the physical characteristics of the material. This allows us to approximate processes and determine new values of the physical characteristics of the material, including temperature and moisture content. The proposed algorithm for the use of cellular automata makes it possible to obtain a reliable result unnecessarily to conduct complex and expensive practical experiments. To speed up the calculation process, propose to use multilayered, which consists in obtaining numerical values of the physical characteristics of the material from several adjacent cells, which are located in the same direction of interaction. The work also provides graphs of changes in temperature and relative humidity of the wood drying agent. In this work is also given graphs of changes in temperature and moisture content of wood inside and on its boundary. To check the adequacy and reliability, all results are compared with the results of another experiment. To check the adequacy and reliability, we compared the obtained results with the results of another experiment. For this comparison in work it is calculated the relative error between the temperature and moisture content values of both experiments. The value of this relative error makes it possible to determine the prospects for the use of cellular automata in the simulation of heat and moisture transfer processes in wood drying chambers. Keywords: сellular automata; CAD model; algorithm of work; transition rules; wood drying chamber.

Physical and technical aspects of the technology of energysaving drying of wood in chambers with natural circulation of the agent

The problems of energy saving are one of the most urgent problems of modern industry and timber processing is no exception in this. In all wood processing, wood drying stands out for its energy consumption. A possible direction for significantly reducing the energy intensity of wood drying is the use of modes based on the phenomenon of thermal and moisture conductivity in chambers with a natural circulation of the drying agent. The theoretical and experimental studies carried out by the authors made it possible to create a wood drying technology that reduces the energy consumption of the process by 40-45% with a certain (15-17 %) loss in the productivity of drying equipment compared to chambers operating with forced circulation of the drying agent.

The Natural Durability and Drying Properties of Ganitri Wood (Elaeocarpus sphaericus Schum)

Ganitri (Elaeocarpus sphaericus Schum.) is a fast-growing species that was majority planted in community-based forets in Java. This research aimed to evaluate the natural durability and drying properties of ganitri wood, hence the best uses of the wood can be achieved. The wood durability was tested in laboratory and field scales based on SNI 7207:2014 and ASTM D 1758-02 standards respectively, while the wood treatibilty evaluation used soaking method with 5% borax preservative. The wood drying property was assessed through oven drying at 100°C temperature based on Terazawa method. The resistance of the wood against subterranean termites Coptotermes curvignathus is classified as durability class IV. Ganitri wood was very easy to be preserved with the cold soaking method. Boron retention in ganitri was 22.87 kg.m-³, while its penetration was 27.80 mm or 94.24%. Ganitri had rather poor drying properties, which was prone to surface check. The proper drying for ganitri wood was suggested using initial and final temperatures 53°C and 83°C, respectively, while the initial and final relative humidity were 85% and 30%.

Numerical Simulation of the Water Vapor Separation of a Moisture-Selective Hollow-Fiber Membrane for the Application in Wood Drying Processes

In this study, a simplified two-dimensional axisymmetric finite element analysis (FEA) model was developed, using COMSOL Multiphysics® software, to simulate the water vapor separation in a moisture-selective hollow-fiber membrane for the application of air dehumidification in wood drying processes. The membrane material was dense polydimethylsiloxane (PDMS). A single hollow fiber membrane was modelled. The mass and momentum transfer equations were simultaneously solved to compute the water vapor concentration profile in the single hollow fiber membrane. A water vapor removal experiment was conducted by using a lab-scale PDMS hollow fiber membrane module operated at constant temperature of 35 °C. Three operation parameters of air flow rate, vacuum pressure, and initial relative humidity (RH) were set at different levels. The final RH of dehydrated air was collected and converted to water vapor concentration to validate simulated results. The simulated results were fairly consistent with the experimental data. Both experimental and simulated results revealed that the water vapor removal efficiency of the membrane system was affected by air velocity and vacuum pressure. A high water vapor removal performance was achieved at a slow air velocity and high vacuum pressure. Subsequently, the correlation of Sherwood (Sh)–Reynolds (Re)–Schmidt (Sc) numbers of the PDMS membrane was established using the validated model, which is applicable at a constant temperature of 35 °C and vacuum pressure of 77.9 kPa. This study delivers an insight into the mass transport in the moisture-selective dense PDMS hollow fiber membrane-based air dehumidification process, with the aims of providing a useful reference to the scale-up design, process optimization and module development using hollow fiber membrane materials.

Effects of the Existence of Fan in the Wood Drying Room and the Performance of the Electric Energy Wood Dryer

The purpose of this study is to determine the effect of the presence of a fan in the wood drying room in the drying time of wood. In addition, it is also to determine the performance of the steam compression cycle engine used in wood drying machines and the conditions of air entering and leaving the wood drying room. Wood drying machines work on a source of electrical energy. The research was conducted experimentally. Variations in the study were carried out on the presence of fans in the drying room: (a) there were no fans and (b) there were 2 fans. The dried object is a sengon wood board, which has a length of 2 m, a width of 20 cm, and a thickness of 2 cm. The number of wooden planks is 70 wooden planks of uniform size. The wooden planks before drying have a moisture content of 29.6%, and when dry, have a moisture content of 10%. The research gave the following results: (a) if there are 2 fans in the drying room, the time needed to dry the sengon wood planks is around 42.6 hours, whereas if there is no fan around 49.9 hours (b) the average Coefficient of Performance (COP) of the steam compression cycle engine is 10.65 (c) The air condition enters the drying room when there are 2 fans, has a dry ball air temperature of 40oC with a relative humidity of 32% RH and the air condition when it comes out, has a dry ball air temperature of 28oC with a relative humidity of 73% RH.

Wood Drying In Construction

The article shows the indicators of the coefficients of shrinkage of wood, stages of shrinkage, the effect of the density of shrinkage of wood.

Drying Stress and Strain of Wood: A Review

Wood drying stress causes various drying defects, which result from the wood microstructure and the transfer of heat and mass during the drying. It is the fundamental way to solve the problem of defects to clarify the law and mechanism of wood stress and strain development during drying. In this paper, based on the defects of wood drying, the theory and experimental testing methods of drying stress and strain were summarized. Meanwhile, artificial neural networks (ANN) and their application in the wood drying field were also investigated. The traditional prong and slicing methods were used practically in the research and industry of wood drying, but the stress changes in-process cannot be trapped. The technologies of image analysis and near-infrared spectroscopy provide a new opportunity for the detection of drying stress and strain. Hence, future interest should be attached to the combination of the theory of heat and mass transfer and their coupling during drying with the theory of microscopic cell wall mechanics and macroscopic drying. A more complete image acquisition and analysis system should be developed to realize the real-time monitoring of drying strain and cracking, practically. A more feasible and reasonable prediction model of wood drying stress and strain should be established to achieve the accuracy of the prediction.