Автор: Ladislav Dzurenda

Статии

COMPUTATION OF THE AVERAGE WOOD TEMPERATURE AND THE RATE OF ITS CHANGE DURING UNILATERAL HEATING OF FLAT SPRUCE DETAILS BEFORE THEIR BENDING

Автори: Nencho Deliiski, Neno Trichkov, Dimitar Angelski, Ladislav Dzurenda

Резюме

An approach for the computation of the average mass temperature of the wood and the rate of its change during unilateral heating of flat wood details aimed at their plasticizing in the production of curved outside parts for corpses of stringed music instruments, has been suggested. The approach is based on the numerical integration of the solutions of a linear model for the calculation of the non-stationary 1D temperature distribution along the thickness of subjected to unilateral heating flat wood details.

Ключови думи: average mass temperature, rate of change in average temperature, spruce details, unilateral heating, plasticizing

EN Version

INFLUENCE OF THE TEMPERATURE COMBUSTION OF FUEL-WOOD TO CONTENT ASH

Автори: Ladislav Dzurenda, Adrián Banski

Резюме

In this contribution, there are presented the results of experiments determining the influence of combustion temperature of fuel-wood on the production of ash. They confirm current knowledge about the low production of ash from wood, and specify the functional dependences between the influence of temperature at intervals of t = 500°C – 1000 °C on the production of ash from the wood of tree species: Norway spruce, White birch, European beech, English oak and Black locust.

The functional dependences of ash production on the combustion temperatures are instrumental for objectification of information about ash production from energy facilitiesfor energy, environmental, and ecological analyses and balances.

The proportion of ash from fuel-wood can be done according to standard ISO 1171:2003, or standard EN14775:2010. These standards differ in the temperature of combustion of the fuel wood sample. ISO 1171:2003 burns fuel at t = 815 °C while EN14775:2010 at t = 550 °C. Disregarding the aforementioned facts about the dependence of production of ash on the combustion temperature causes errors. By interchanging the norms ISO1171:2003 with EN14775:2010, the balances from combustion of spruce wood generate a relative error of 44.58%. The balances from combustion of wood of black locust generate a relative error of 19.10%.

Ключови думи: fuel, wood, combustion, temperature, ash

EN Version

COMPUTATION OF THE ENERGY CONSUMPTION FOR WARMING UP OF FLAT OAK DETAILS BEFORE THEIR BENDING

Автори: Nencho Deliiski, Neno Trichkov, Dimitar Angelski, Ladislav Dzurenda, Zhivko Gochev, Natalia Tumbarkova

Резюме

A software program has been prepared in the calculation environment of Visual Fortran for solving of own 1D non-linear model of the one sided heating process of flat wood details. With the help of the program, the 1D non-stationary temperature field in flat oak details with initial temperature of 20 oC, moisture content of 0.15 kg.kg-1, thickness of 12 mm, 16 mm, and 20 mm during their 30 min one sided heating at temperature of 80 oC of the heating metal body has been calculated. After integration of the temperature field, the energy consumption for warming up of the details before their bending in the production of curved back parts of chairs has been calculated. The obtained results are graphically presented and analyzed.

Ключови думи: oak details, one sided heating, bending, energy consumption

EN Version

WOOD COLOUR MODIFICATION OF FRAXINUS EXCELSIOR L. DURING THE PROCESS OF THERMAL TREATMENT WITH SATURATED WATER STEAM

Автори: Ladislav Dzurenda, Adrián Banski

Резюме

The aim of the paper is to determine the colour of European ash wood (Fraxinus excelsiorL.) in the CIE-L*a*b* colour space during the thermal treatment with saturated water steam at the temperature of t = 137.5 ± 2.5 °C for the time of τ = 7.5 hours. The colour of European ash wood changes from white with a yellow hue to brown during the process of colour modification. Mentioned hue of thermally modified wood is described with the coordinates of CIE-L*a*b*colour space:  L* 65.6 ± 1.4; a* = 10.8 ± 0.5; b* = 21.7 ± 0.9. Irreversible colour change of the European ash wood resulting from the process of thermal modification with saturated water steam widen the possibility for its use in the field of construction and carpentry, design as well as in the field of art.

Ключови думи: wood, European ash (Fraxinus excelsiorL.), the CIE-L*a*b*colour space, thermaltreatment, saturated water steam

EN Version