This study puts forward an approach for calculating the specific energy consumption and its components required for heating of frozen logs for veneer production, depending on the logs’ initial temperature and moisture content. The approach is based on the use of two personal models: unsteady model of the temperature distribution along the radius of frozen logs during their thermal treatment and stationary model of the energy consumption of logs subjected to such treatment as a function of its four multifactorial components. The influence of all combinations between five values of the initial temperature of frozen logs from −1°C to −40°C and three values of their moisture content from 0.4 kg·kg⁻¹–0.8 kg·kg⁻¹ on the specific energy required to heat and placticize beech logs with a diameter of 0.4 m at operating temperature of the steaming or boiling medium of 80 oC was investigated. The obtained results show that this energy changes in the range from 46 kWh·m⁻³ (at −1°C and 0.4 kg·kg⁻¹) to 114 kWh·m⁻³ (at −40°C and 0.8 kg·kg⁻¹) The approach could be applied to calculate the energy and its components required for carrying out of the thermal treatment of various frozen capillary-porous materials.

An approach for calculating the energy required for defrosting and subsequent heating of frozen wood during thermal treatment in the production of veneer has been presented. Using two own unsteady models the duration of regimes for steaming of prisms in an autoclave and for boiling of logs in a pit, and also the average mass temperature of the prisms and logs and the energy accumulated by them at the end of heat carrier introduction in these regimes was determined. The obtained values of average temperature were introduced in third own model for engineering calculation of the energy considered in the approach. Computer simulations were carried out for beech prisms with a cross section of 0.4 × 0.4 m and beech logs with a diameter of 0.4 m at an initial wood temperature of −10°C, −20°C, and −30°C and moisture content of 0.6 kg·kg−1. The operating temperature of the prism steaming regimes was equal to 130°C, and that of the log boiling regimes was 80°C. The approach can be applied using Excel for computing the energy and its components needed for defrosting and heating of different frozen capillary-porous materials subjected to multiple types of thermal treatment.

Beech wood, renowned for its diverse applications spanning construction, flooring, furniture, veneer, and plywood, holds a paramount position among industrial wood species. Nevertheless, the myriad of beech species worldwide, coupled with the dynamic impact of climate change, have produced structural variations within beech trees. Extensive research has scrutinized the physical and mechanical attributes of beech wood species across the globe. Findings reveal distinguishable mechanical strength, yet increased density leads to notable rates of shrinkage and swelling, somewhat constraining its utility in select domains. Identifying research gaps can create new efforts aimed at exploiting the potential of these wood resources. This paper outperforms a mere exploration of beech wood properties over the past two decades; it delves into the ramifications of climatic fluctuations, temperature shifts, wind dynamics, and soil composition. Given the lack of a comprehensive compendium documenting the full range of physical, mechanical, and microscopic attributes of the Fagus genus, this paper aims to compile information that integrates this multifaceted information.

This study aimed to investigate the combined effect of steaming and heating on the equilibrium moisture content (EMC) of Turkey oak (Quercus cerris L.) wood over a nine-year period. The study also aimed to determine the impact of steaming on water absorption and water permeability, crucial for the durability of the species against environmental factors. The specimens underwent thermal modification with and without steaming, then were stored under laboratory conditions for ten years. The mass of the specimens was monitored throughout the ten-year period. To measure the water uptake capacity, the specimens were soaked in water for 120 hours. The water permeability of the specimens was assessed using a pressurised chamber. The results showed that the moisture content of thermally-modified oak was constant under laboratory conditions after nine years, further improved by steam treatment. The research also revealed that the steamed wood absorbed more water during water submersion compared to the unmodified wood. When the steaming treatment was applied, there was a significant increase in permeability in the sapwood compared to the heartwood, due to anatomical variations. Despite this, statistical noise, and material variability, alongside tylosis presence, underline the need for examining more specimens in future studies.

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°C, and a moisture content of 0.6 kg∙kg-1 were determined at water temperatures in the pit equal to 70, 80, and 90°C. 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°C 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.

A methodology for the computation of the thermal energy efficiency of modes for the heat treatment of frozen wooden prisms in an autoclave with saturated water vapor at changing operational conditions has been proposed. The methodology includes computer simulations with two own-coupled unsteady models: one to calculate the 2D temperature distribution in the cross-section of prismatic wood materials during their heat treatment, and the second to determine the heat balance of industrial autoclaves for such wood treatment. Simulations were carried out in order to determine the duration, energy consumption, and thermal efficiency of different modes, caused by changed operational conditions, for the autoclave steaming of frozen beech prisms with industrial parameters in the absence and presence of dispatcher intervention. The influence of nine combinations between the time of dispatcher intervention and the degree of reduction of the constant maximum temperature from the 130 °C of the basic mode on the thermal efficiency of the autoclave was investigated. The results show that all studied dispatching interventions cause an increase in both the duration and the thermal efficiency of the modes. This efficiency in the modes at changing operational conditions has values between 68.7% and 74.6%, while the efficiency in the basic steaming mode is equal to 68.0%.

The rheological properties of wood and wood-based materials are becoming increasingly important both in timber construction, and in furniture and interior design. The topic has already been intensively researched in the 1970s and 1980s. In the context of work on modelling stresses and deformations, and the development of new engineered wood products (EWPs), investigations in this topic have been intensified in recent years. Several projects are ongoing, mostly concerning basic research on the rheological properties on solid wood. The objective of this study was to give an update on the state-of-the-art on creep behaviour of wood and wood-based materials, and to present some research questions relevant for the further development of the field. Characteristic values for Kdef, i.e. correction factors to be taken into account due to creep of the material according to Eurocode 5, are usually used as a characteristic value in the timber construction. Because of the following reasons, basic studies on rheological properties of wood and woodbased materials are still largely lacking:

● the development of new EWPs, especially from hardwoods, 

● the use of new adhesive systems and the related change in adhesive properties,

● the reduction of formaldehyde content in adhesives for particleboard and medium-density fibreboard (MDF), and

● the increased use of waste wood and recycled wood in particleboard production (up to 100% particles may be based on waste wood or recycled wood). 

This study investigates the influence of different machining processes on the tensile shear strength of glued lumber, focusing on optimizing the tool geometry of face milling. The data obtained were analyzed using statistical methods. The roughness of the surface produced by the machining process and the damage to the microstructure under the cutting edge are identified as important factors influencing the quality of the bond. The results show that the optimized process (low roughness and microstructure damage) leads to more effective gluing.