Автор: Dimitar Angelski

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

COMPUTATION OF THE HEAT FLUX NEEDED FOR UNILATERAL WARMING UP OF FLAT SPRUCE DETAILS BEFORE THEIR BENDING

Автори: Nencho Deliiski, Neno Trichkov, Dimitar Angelski, Zhivko Gochev

Резюме

An approach for the computation of the heat flux, which is needed for warming up of flat wood details during unilateral heating 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 and differentiation 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. The paper presents solutions of the model concerning the non-stationary change in the specific heat flux needed for warming up of flat spruce details with thicknesses of 6, 8 and 10 mm during their unilateral heating at temperatures of the electrically heated metal band equal to 100, 120, and 140 oC.

Ключови думи: unilateral heating, flat wood details, heat flux, plasticizing, bending

EN Version

TRANSFORMATION OF TWO MUTUALLY CONNECTED MODELS FOR CONVECTIVE HEATING OF WOOD DETAILS BEFORE THEIR LACQUERING IN A FORM, SUITABLE FOR PROGRAMMING

Автори: Nencho Deliiski, Neno Trichkov, Zhivko Gochev, Dimitar Angelski

Резюме

Using the explicit form of the finite-difference method, two suggested by the authors mutually connected mathematical models have been transformed in a form, suitable for programming. For the numerical solution of the transformed models, a software program has been prepared in the calculation environment of Visual Fortran Professional. With the help of the program, the 1D distribution of the temperature along the thicknesses of flat oak details and of their carrying transport rubber band with hw = 16 mm, lw = 0.6 m, u = 0.08 kg.kg-1, hB = 4 mm,
bB = 0.8 m, and t0 = 20 oC, during unilateral convective heating for a period of 10 min at tha = 100 oC, vha = 2 m·s-1, 5 m·s-1, 8 m·s-1, and tnha = 20 ºC in order to ensure suitable thermal conditions for the subsequent details’ lacquering has been calculated, visualized and analyzed.

Ключови думи: oak details, unilateral convective heating, lacquering, carrying rubber band

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

COMPUTATION OF THE AVERAGE MASS THERMAL CONDUCTIVITY OF OAK FURNITURE ELEMENTS SUBJECTED TO CONVECTIVE HEATING BEFORE LACQUERING

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

Резюме

A methodology for the computation and research of the following two mutually connected problems has been suggested: 1D non-stationary temperature distribution in subjected to unilateral convective heating process of flat wooden furniture elements before lacquering and change in their average mass thermal conductivity. For the realization of the methodology, created earlier by the authors 1-dimensional nonlinear mathematical model has been solved for the transient heat conduction in the furniture elements during their unilateral convective heating. The model contains a mathematical description of the average mass thermal conductivity of the elements and their surface layer, which is intended for lacquering. For the numerical solution of the model with the aim of applying the methodology a software program has been prepared and input in the calculation environment of Visual FORTRAN Professional. Using the program, computations have been carried out for determination of the 1-dimensional non-stationary temperature distribution along the elements’ thickness and of the average mass thermal conductivity for flat oak furniture elements with an initial temperature of 20 oC, moisture content of 8 %, thickness of 16 mm, width of 0.6 m, and length of 1.2 m during their 10 min unilateral convective heating at temperature of the processing air medium of 100 oC, which circulates above the elements with a velocity of 2 m·s-1, 5 m·s-1, and 8 m·s-1 aimed at improvement of the conditions for the subsequent lacquering. During the computations a temperature of 20 oC for the surrounding air near the non-heated surface of the carrying rubber band has been used. The change in the average mass thermal conductivity of the studied furniture oak elements and also of their heated surface layers during the heating is graphically presented and analyzed.

Because of the wide range of applications, the need for paulownia is constantly increasing.

Ключови думи: oak furniture elements, one sided convective heating, lacquering, thermal conductivity

EN Version