автоматика
Н. Делийски, Е. Михайлов, Н. Тумбаркова, Н. Пенкова. Математично описание на латентната топлинна енергия на свободната вода в дървесината


СЪДЪРЖАНИЕ

Кey Words: Logs; modeling; freezing; free water; icing degree; latent thermal energy.

Abstract. An approach for the computation of the specific (for 1 m3 wood) latent thermal energy of the free water, QLheat-fw, in logs subjected to freezing has been suggested. The approach takes into account to a maximum degree the physics of the freezing processes of the free water in wood. It reflects the influence on the mentioned energy of the wood density, the icing degree formed by the freezing of free water in the logs, as well as the influence of the fiber saturation point of each wood species. Mathematical description of the specific thermal energy QLheat-fw, which is released in logs during the free water freezing in the range from 0 oC to –1 oC, has been executed. This description is introduced in own 2D non-linear mathematical model of the freezing process of logs. For the solution and verification of the model and for the computation of the energy QLheat-fw, a software program based on the suggested approach and mathematical description was prepared in FORTRAN, which was input into the calculation environment of Visual Fortran Professional. With the help of the program computations have been carried out for determination of the energy QLheat-fw of two beech and two poplar logs with a diameter of 0.24 m, length of 0.48 m, and moisture content above the hygroscopic range during their many hours freezing in a freezer at approximately –30 oC. The information about QLheat-fw is needed for scientifically based computing the energy consumption of the freezing and also of the subsequent defrosting processes of logs aimed at their plasticizing in the production of veneer.

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