Experimental measurements of heat and mass transfer during convective drying of southern pine

SummaryThe transport of heat and moisture during the convective drying of southern pine was examined experimentally. Moisture distribution within the wood samples was measured using gamma attenuation. The accuracy of these measurements was found to be moisture content dependent with estimated uncertainties ranging from 29.5% at 10% moisture content to 6.8% at 120% moisture content. Local moisture content measurements reveal large inflections at high moisture contents. Peaks in moisture content are closely correlated with low fwood density and vice versa. Above the fiber saturation point the measured drying rate is not a well defined function of the moisture content. This is perhaps due to the biological variability of wood as well as grain orientation, although no definite conclusions could be drawn from the data with regard to the effect of grain orientation. The drying rate does not appear to be highly temperature dependent at high moisture contents. Below the fiber saturation point where diffusion is expected to be the dominant transport mechanism, the drying rate is less affected by biological variability and grain orientation, however, the effects of temperature are evident.