Автор: Ladislav Dzurenda

Статии

THE SHARE OF BARK IN ENERGY CHIPS FROM SHORT ROTATION COPPICE OF POPLARS AND WILLOWS GROWN ON PLANTATIONS

Автори: Ladislav Dzurenda, Miroslav Dzurenda

Резюме

In this contribution, the results of experimental works assessing the share of bark in energy chips of selected clones of short rotation coppice of Salix viminalis and poplars with 5-year harvesting cycle, grown in the region of Slovakia and Moravia, are shown. Energy chips made of dendromass from fast growing trees grown on plantations is a bio-fuel consisting of juvenile wood and juvenile bark. The share of bark in energy chips influences the environmental properties and ash content of a bio-fuel.

The share of bark in energy chips from clones RAPP, OLM, ULV and Inger of Salix viminalis in bio-fuel is XB = 16,8 ÷ 19,7 % and the share of bark in chips from clones Max5, Oxford, AF2 a Monviso of poplars grown on plantations is XB = 20,97 ÷ 26,67 %.

Ключови думи: bio-fuel, energy chips, share of bark, fast-growing trees, Salix viminalis, Populus

EN Version

MODELING OF THE DEFROSTING PROCESS OF PRISMATIC BEECH MATERIALS

Автори: Ненчо Делйски, Ladislav Dzurenda, Славчо Соколовски, Камен Пецов

Резюме

By the first co-author earlier a 3-dimensional mathematical model has been created, solved, and verified for the transient non-linear heat conduction in frozen prismatic wood materials during their heating. Now in the model the dependence of the fiber saturation point of the separate wood species from the temperature has been incorporated.

The paper presents graphically solutions of the updated model of the obtained calculated results about the temperature distribution in the volume of beech frozen materials with prismatic shape with thickness 0,4 m, width 0,4 m, length 0,8 m, initial temperature -40 оC, and moisture content 0,3 kg.kg-1 and 0,6 kg.kg-1 during their defrosting at temperature of the processing medium of 80 оC.

Ключови думи: frozen wood, beech prisms, defrosting, modeling, temperature distribution

EN Version

APPLYING OF MS EXCEL 2010 FOR 2D COLOUR VISUALIZATION OF TEMPERATURE FIELDS IN LOGS DURING THEIR DEFROSTING PART 1. SEQUENCE OF PROCEDURES FOR THE CREATION OF 2D COLOUR DIAGRAMS USING MS EXCEL 2010

Автори: Ненчо Делйски, Иван Христов, Веселин Брезин, Ladislav Dzurenda, Радослав Милчев, Славчо Соколовски

Резюме

A methodology for the creation of colourful 2D diagrams using MS Excel 2010, illustrating the temperature distributions in the longitudinal sections of frozen logs during different moments of their defrosting, has been suggested in this paper. For the creation of the diagrams numerical results have been used, which represent the solutions to a non-linear mathematical model of the logs’ defrosting process. These numerical results are presented in files in the .txt format before their processing with the software of MS Excel 2010 aiming at the creation of the 2D colourful diagrams.

Ключови думи: 2D visualization, temperature fields, wood defrosting, oak logs, MS Excel 2010

EN Version

APPLYING OF MS EXCEL 2010 FOR 2D COLOUR VISUALIZATION OF TEMPERATURE FIELDS IN LOGS DURING THEIR DEFROSTING PART 2. 2D VISUALIZATIONS OF THE TEMPERATURE FIELDS IN OAK LOG IN DIFFERENT MOMENTS OF THEIR DEFROSTING

Автори: Ненчо Делйски, Иван Христов, Веселин Брезин, Ladislav Dzurenda, Радослав Милчев, Славчо Соколовски

Резюме

In the first and at the beginning of the second part of this work the methodology for creation of 2D colourful diagrams has been described as thematically-oriented sequence of the used procedures of MS Excel 2010. In this part of the work the methodology has been applied for the preparation of 2D colourful diagrams of temperature distribution in the longitudinal sections of a frozen oak log during its defrosting. The methodology can be used for the preparation of various 2D diagrams for the change of temperature, moisture, and other fields in the volume of different materials in the cases when the diagrams are created using extensive numerical results from models, adequately describing the studied processes.

Ключови думи: 2D visualization, temperature fields, wood defrosting, oak logs, MS Excel 2010

EN Version

ENERGY CHARACTERISTICS OF BIOFUELS – WOOD CHIPS FROM DENDROMASS OF PLANTATION GROWN BLACK LOCUST

Автори: Ladislav Dzurenda, Adrián Banski

Резюме

In the present paper, energetic properties of wood chips of the species Robinia pseudoacacia (clones Ambigua, Debrecenyi 2, Göri, Matyasi, Nyirsegi, Rozaszin, Zalyi)  ere determined, relative humidity of chips during a harvest, bulk density, namely the share of bark in chips, chemical composition of combustibles of chips, ash content in dry mass of biofuel, and lower heating value. Green wood chips made of dendromass from plantations consist of juvenile wood and juvenile bark. The share of juvenile bark in green wood chips of the analyzed clones of Robinia pseudoacacia is XB = 22.97 ± 1.95 %.

The nitrogen content in green wood chips made of Robinia pseudoacacia  trees grown on plantation is 8 times higher than the nitrogen content in the combustibles of fuelwood of broad-leaved tree species, which has negative impact on the production of emissions – concentration of nitrogen oxides NOx in combustion products. The share of inorganic substances determined by the form of ash content Ad = 1.73 % puts the analyzed biofuel into the category of low-ash fuels. The lower heating value of green wood chips of the individual Robinia pseudoacacia  clones analyzed in dry state is Qn = 18.0 MJ.kg-1.

Ключови думи: bio-fuel, energy chips, Robinia pseudoacacia, humidity, bulk density, share of bark combustibles, ash, lower heating value

EN Version