Abstract:

The nature of moisture flux and heat flux in wood pre-heating is analyzed by means of coupled flux equations,which are derived from the linear theories of non-equilibrium thermodynamics.The coupled flux equation is solved by integrating on the boundary of the wood sample and the moisture change in the sample is work out.The calculation is in agreement with the previous results from experiment.It shows that the coupled flux equations are effective on analyzing the coupling between the heat flux and moisture flux.They can both depict the heat flux and moisture flux qualitatively and also estimate the magnitude of flux quantiatively.Because the temperature inside wood sample is lower than that of pre-heating,moisture thermal diffusion occurs due to the Soret effect and the moisture of wood sample will increase to some degree in the pre-heating process.During that period,the moisture and energy transported into wood amount to almost all of both total magnitudes within two hours.The conclusions for wood pre-heating obtained in this paper can be used in the wood drying techniques and are useful to practical production.

Key words: Coupled flux equation, Wood drying, Heat conduction, Mass transfer, Thermal diffusion