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An advanced control system is considered for wood Thermal Treatment Processing (TTP) in order to cope with the scarcity of on-line measurements as well as cope with a variety of unpredictable operational conditions arising due to disturbances and large uncertainties. The architecture of the proposed control system includes a number of Building Blocks (BB), functionally based on well-established algorithms, so that that the design and operation of the system use mainly parameterisation via simulation, optimization and coordination. In the created BB a set of advances are incorporated: first principle modelling of WEP, inference control, Run-to-Run optimization, Case-Based Reasoning (CBR). Some results of real applications in SMEs are presented.

This paper presents an approach for computing the heat balance of boiling pits during plasticising of non-frozen logs intended for the production of peeled veneer. With the help of our own non-stationary model, the heating times of beech logs with a diameter of 0.4 m, an initial temperature of 10℃, and a moisture content of 0.6 kg·kg-1 were determined at water temperatures in the pit equal to 70, 80, and 90℃. Using the determined logs' boiling durations and the mentioned approach, the change in the total energy required to carry out the entire boiling process and that required for each of the individual components of the heat balance was calculated. Computer simulations were conducted for a concrete pit with overall dimensions of 8.0 × 2.6 x 2.5 m, working volume of 20 m3, and a degree of filling with logs equal to 45, 60, and 75%. It was found that the increase in the water temperature from 70 to 90℃ causes an increase in the total specific energy, as well as in the energy for the heating of the logs themselves, the construction and the water of the pit. At the same time, the energy required to cover the heat losses of the pit decreases and the energy for heating the metal heater/radiator itself does not change. A decrease in the degree of filling of the pit with logs from 75 to 45% causes an increase in both the total energy and all its components except the energy for heating the logs, which remains unchanged. [ABSTRACT FROM AUTHOR]

An approach to mathematical modeling and research on the 2D non-stationary temperature distribution in non-frozen wooden prisms with different thicknesses during their simultaneous autoclave steaming at limited heat power of the steam generator and during the subsequent air conditioning before the cutting of veneer is described in the paper. Mathematical descriptions of the changing processing medium temperature in an autoclave and near the steamed prisms out of the autoclave were introduced as boundary conditions in our own 2D non-linear mathematical model of the 2D temperature distribution in non-frozen prisms during their heating and cooling. Numerical solutions of the model in the calculation environment of Visual FORTRAN Professional are given as an application of the suggested approach. Simulative investigation of 2D non-stationary temperature distribution in nonfrozen beech (Fagus Sylvatica L.) prisms with an initial temperature of 0 °C, cross-section dimensions of 0.3 × 0.3 m, 0.4 × 0.4 m, and 0.5 × 0.5 m, moisture content of 0.4, 0.6, and 0.8 kg·kg-1, during their autoclave steaming and subsequent conditioning was carried out. The simultaneous steaming of all prisms was simulated according to regimes for prisms with cross-section dimensions of 0.5 × 0.5 m in an autoclave with a diameter of 2.4 m, length of 9.0 m and loading levels of 40, 50, and 60% at a limited heat power of the steam generator, equal to 500 kW. It was found that good quality veneer could be obtained after simultaneous steaming of prisms of the same wood species with differences between their thicknesses up to 100 mm. It is necessary to carry out the steaming according to the regime that applies to the prisms with the largest thickness in a given batch. Then the effect of the wood moisture content and loading level of the autoclave on the plasticization degree of the prisms and the veneer quality is practically negligible. The suggested approach can be used for the computation and model based automatic realization of energy-efficient optimized regimes for autoclave steaming of different wood materials. [ABSTRACT FROM AUTHOR]

This paper describes the results from an experimental research according to original methodology of the following parameters of the logs' freezing process: change in the temperature and relative humidity of the air processing medium in the freezer used for the experiments; temperature distribution in the longitudinal section of logs subjected to freezing; distribution of wood moisture content and of basic density of the wood in the separate layers of the logs' cross-section. The methodology is used for research of the mentioned parameters during many hours freezing in a freezer at a temperature of approximately -30 C of pine logs with a diameter of 240 mm, length of 480 mm and moisture content above the hygroscopic range. The automatic measurement and record of the temperature and the relative humidity is carried out by means of Data Logger type HygrologNT3 produced by the Swiss firm ROTRONIC. [ABSTRACT FROM AUTHOR]

This article presents an approach for computing the 2D temperature field, average mass temperature, and relative icing degree of logs subjected to many days and nights of continuous alternating freezing and thawing at periodically changing air temperature near them in winter. Mathematical descriptions of the periodically changing atmospheric temperature in winter and of the icing degree of the logs under the influence of that temperature have been carried out and entered in own mutually connected 2D models of logs' freezing and thawing processes. Results from simulations with the models of the change in the 2D temperature field, average mass temperature, and relative icing degree of beech logs with a diameter of 240mm, length of 480mm, moisture content of 0.6kg·kg-1, and initial temperature of 0oC during their 5 days continuous alternating freezing and thawing at changing atmospheric temperature with different initial values below -5oC and different amplitudes are shown and analyzed. [ABSTRACT FROM AUTHOR]

A programmable control system for the convective drying process of lumber in chambers is developed, based on specially designed drying algorithm, which allows for computing the set-point values for the temperature and the relative humidity of the heating and drying air as a function of the wood species, lumber thickness and the initial and desired final wood moisture content. The system allows for carrying out model predictive automatic control, by means of which, after the operator enters the data on wood species and thickness of the lumber, as well as the initial moisture content and the desired final value of the moisture content, the programmable controller in the system calculates the current values for the temperature and the relative humidity of the processing air medium, and also the duration of the separate stages of the drying process, and carries out an automatic realization of the computed parameters. An application of the developed system for predictive automatic control of the convective drying process of pine lumber with thicknesses of 32 mm and 76 mm is given and visualized. [ABSTRACT FROM AUTHOR]

Mathematical descriptions of thermal conductivity λw, specific heat capacity cw, heat transfer coefficient αw, and density ρw of non-frozen wood in hygroscopic range have been introduced in own 1D non-linear mathematical model of one sided conductive heating process of flat wood details. For the numerical solution of the model a software program has been prepared in the calculation environment of Visual FORTRAN Professional. By means of the program, the 1D non-stationary temperature distribution along the thickness of subjected to one sided conductive heating flat wood details, aimed at their plasticizing in the production of curved back parts of chairs, has been calculated. The change of λw for beech details with an initial temperature of 20 oC, moisture content of 0.15 kg.-1, and thicknesses of 12 mm, 16 mm, and 20 mm during their 30-min. one sided heating at temperature of 100 oC of the heating metal body has also been computed, visualized and analyzed. [ABSTRACT FROM AUTHOR]