Drying timber

Langrish, The Significance of the Gaps between Boards in Determining the Moisture Content Profiles in the Drying of Hardwood Timber, Drying Technol 17(R. 7-8) 1481-1494 (1999). 

Some time ago Kamke and Vanek (1994) compared the performance of a number of within-the-timber drying models, representing mainly diffusion-like and multiple-transport mechanism approaches, for predicting average moisture contents and moisture-content profiles. Four data sets were used, with three sets representing idealised problems. The fourth data set was the experimental results of drying 40 mm boards of Norway spruce, Picea abies, from initial moisture contents of 29-66% at a dry-bulb temperature of 60°C, wet-bulb depressions of 8-25°C, and an air velocity of 6 m s. The required inputs for the models, including physical properties... 

Pang, S., External Heat and Mass Transfer Coefficients for Kiln Drying of Timber, Drying Technology, 1996, 14(3 4), pp. 859-871. 

Splits and cracks during timber drying can be observed in large wooden beams, while in smaller ones, deformations related to the different face orientations can be observed (Figures 12.4 and 12.5). 

Langrish, T.A.G., 1999. The significance of gaps between boards in determining the moisture content profiles in the drying of hardwood timber. Drying Technol., 17 1481-1494. 

Pratt, G.H. and Turner, C.H.C., 1986. Timber Drying Manual, 2nd ed.. Building Researeh Establishment Garston, HMSO, London, U.K. 

RUey, S.G. and Haslett, A.N., 1996. Reducing air velocity during timber drying, in Proceedings of the Fifth International lUFRO Wood Drying Conference, Montreal, Qudbec, Canada, pp. 301-308. 

Energy Performance of a Heat Pump Dryer for Timber Drying... 

FIGURE 55.20 Schematic diagram of a heat pump dryer for timber drying. 

Rotorua (Bannister et al, 1999). It can be observed that the dryer performed with better energy efficiency (measured by SMER) when more water was removed. It is expected because of the higher amount of latent heat recovered when higher amount of water is removed. This would translate to a shorter payback period for higher volume of timber dried. 

Geeraert B. Air drying by heat pumps with special reference to timber drying Heat Pumps and Their Contribution to Energy Conservation. NATO Advanced Study Institute, Series E Applied Sciences 15 219-246, 1975. 

---