An approach for computing the specific heat capacities of logs stored for a long time in an open warehouse

A Simulation Study of the Heat Balance of Concrete Pits During Boiling of Non-Frozen Logs

“…When τ 2 is reached, the logs subjected to boiling reach the optimal temperature required for their subsequent mechanical processing in the veneer production. Mathematical descriptions of all the thermo-physical characteristics of the non-frozen wood, which are involved in model ( 1) − (3), have been carried out and verified with foreign experimentally obtained dissertation data in Deliiski [2][3][4][5] and Deliiski et al [7] as a function of the temperature and wood moisture content. The mathematical description of the operating medium temperature in the pit shown in Figure 1, t m , is analogous to that proposed in Deliiski [2], and Deliiski and Dzurenda [6] for t m in autoclaves for steaming wood materials.…”

“…Figure 4 presents the change of all the components of the heat balance of the pit, as well as the total energy Q pit-total (in kWh•m -3 ) required to carry out the entire boiling process, during which the average mass temperature of the logs rises from its initial value t w0 = 10°C to the final average mass temperature t avg-end = 66.8°C at t m1 = 70°C, t avg-end = 72.7°C at t m1 = 80°C, and t avg-end = 78.62°C at t m1 = 90°C. At these values of t avg-end the temperature in the centre of the logs becomes equal to t wc = 62°С, which corresponds to the minimum required temperature necessary to obtain quality veneer from plasticised beech logs [2,7,19].…”

“…Figure 3 shows that the boiling process of the studied logs having the initial temperature t w0 = 10°C and the moisture content u = 0.6 kg•kg -1 ends as follows: after τ 2 = 27.0 h at t m1 = 70°C; after τ 2 = 20.0 h at t m1 = 80°C, and after τ 2 = 16.5 h at t m1 = 90°C. At these values of τ 2 , the temperature of the slowest heating central point of the logs reaches 62°C, which corresponds to the minimum required temperature necessary to obtain quality veneer from heated and plasticised beech logs [2,7,19,25].…”

“…When solving model ( 1) − ( 3), the nonstationary change in temperature along the radius of the log's central cross section is obtained, as well as the moment of reaching a temperature in the centre of the logs equal to t wc = 62°С, which corresponds to the minimum required temperature necessary to obtain quality veneer from the plasticised beech logs [7,19].…”