Status: operational Heating mode: hybrid

Type: chamber dryer Air circulation: electric fan forced convectio

This solar lumber dryer was designed to increase the drying rate of timber as compared to the traditional air drying method. This particular design makes use of large quantities of low temperature heat (up to 60oc) and permits a rapid drying rate without undue degradation of the timber (cracks, warps).

Figure 1. Solar Kiln, Recirculating System with partial Air

Venting. Sheet Reflectors Partially visible on the East and West Sides.


The wood frame structure of the kiln is oriented lengthwise on as east-west axis, the higher wall facing north. Except for the north wall, the whole structure is covered with a double layer of transparent polyethylene sheeting separated by an air gap. The north wall is made of plywood sheeting. The roof is tilted towards south at an angle of 0,9 times the latitude above horizontal (27°). The drying space in the kiln can take about 3,5 cubic meters of 25 mm thick planking (each time), inside the kiln, a horizontal false ceiling covering the entire length of the kiln is installed above the wood stacks. Another false north wall, covering the entire length of the kiln extends from the floor to the false ceiling and is provided with a hole in its center for housing the fan. The built-in interior surfaces within the kiln (the surfaces of wooden roof studs and pillars, the false ceiling and north wall partition, the north wall, the baffles and the concrete floor)

are painted black for a maximum collection of heat. The fan is driven by a 0,75 Kw reversible electric motor and is used for forced air circulation. The use of plywood baffles and movable partitions allows the dryer to be used either as a single-pass flow-through dryer or as a recirculating dryer with partial venting (see figure 3).

Dimensions; See drawings on figure 2 , The south face of the dryer is 3,66 m wide. The 4 vents are 25 cm x 25 em.

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