Large Scale Solar Wood Drying Kilsn

An example of this type is used by the Queensland Forestry Service (see figure below), where they use a roof and three walls of the kiln clad with polycarbonate sheeting that has been fixed to a timber frame, and sealed with silicone sealant and corrugated foam infills. The rear southern wall is lined with both timber on both sides, and the cavity is filled with polystyrene foam. Loss of heat to the ground is restricted by a timber floor in the plenum and concrete in the stack chamber. A reversible fan, 1.1 m in diameter and driven by a 1.5 kW motor, provides air circulation and about one metre per second through the stack. The design uses screens to form a drying room within an outer chamber, so that air can circulate horizontally through the timber stack. Total cost of constructing a kiln of 15 cubic metres capacity in December 1990 was $15 000 (Palmer & Kleinschmidt 1992).

An example of this type was designed by staff of the Australian National University (see figure below). The solar collectors are fabricated from sheet metal and have been designed for easy manufacture. The troughs are glazed with mirror strips. The troughs currently operate at atmospheric pressure and can heat water to over 90 degrees centigrade. The troughs heat water in the collectors which are then used to heat water in a storage tank. This tank is a "heat bank" to store energy for use during the day and well into the night. This heated water is then passed through heat exchangers, to heat the air in the drying chamber. Temperature and humidity are regulated by a logic controlled vent system.