Establishment of specific drying energy of oak-wood flooring deal and thermodynamic model of drying

Total heat consumption per unit of drying evaporation in spring season Cu = 119 MJ/kg has been established by measurement of heat consumption and computation for oak-wood (Quercus robur & petraea) flooring deal 25 mm thick in kiln drying chamber (166.685 m3 of green lumber). The energy consumption per unit of drying evaporation without dissipation is the specific energy of oak-wood flooring deal that for this case amounts to C = 8.6MJ/kg. That total electrical power consumption per unit of drying evaporation has been established in the amount of Cel =0.355 kWh/kg. The above mentioned values are average values through the whole drying cycles. The average initial value of the moisture content was 30% and the final average value of the moisture content was 6.5%. The measurement error of the average result values was around 12%. The cycles were managed by the usual drying process. The established specific drying energy is about 3.5 times greater than the evaporation heat of pure water. Therefore, the general theoretic model has been introduced for explanation of measuring results. This model is a wet air irreversible heat engine considering its thermodynamic sense. The results of such an introduced model are shown as examples in two tables. These results indicate that such a model can be used for a wood drying simulation process with the optional regimes in a technological, energetic and timing sense. The parameter of heat consumption can be an important indication in managing the drying process. Specific drying energy is a function of wood moisture in a determined climate as well as a function of the structural openings from which the water evaporates. The introduced model connects those two parameters.