Reuss, M.; Benkert, S.; Aeberhard, A.; Martina, P.; Raush, G.; Rentzell, B.V.; Sogari, N.
April 1997
Solar Energy, vol 59-4, p. 259-270
In northeast Argentina, several species of hard wood, e.g. Algarrobo and Quebracho, are used for building furniture. To obtain high quality products in this and many other climates, artificial drying is required; typically, wood is dried in convection dryers. In this project the drying air is heated by solar energy in a collector resembling a greenhouse tunnel. Then passing through a drying chamber with the wood stapled inside it removes moisture from the product. The air flow in this special system is generated by natural convection in a chimney due to the lower density of hot air with respect to cold air. At the Institute of Agricultural Engineering of the Technical University Munich a TRNSYS simulation model for the wood drying process was developed using the physical properties of the drying product. Further modules developed describe the collector tunnel, the drying chamber and the chimney. Meteorological data and material coefficients are provided from external data files. Modelling of the wood drying process is advantageous for system design, development of control strategies and system optimization. Especially in applications with solar energy supply and its transient availability such a theoretical model is a helpful tool for research and consultancy. The simulation program predicts moisture and temperature within the product, it also calculates energy flows and ideally achievable drying results. In parallel with this theoretical work in Germany an experimental plant was designed and built in Resistencia, Argentina. The system is equipped with a data acquisition system for detailed monitoring of the solar plant and the drying process. The results gained from this project confirm several advantages of solar wood drying techniques. The drying time is marginally longer than with conventional systems but much shorter than with open air drying. Damage of the wood during drying can be avoided as well as external damage. Operating costs are low since neither special control equipment nor fuel is necessary.
Source: www.sciencedirect.com