Design and Construction of Solar Kiln for Lumber Drying (PDF)

Academic Paper from the year 2015 in the subject Engineering - Chemical Engineering, , language: English, abstract: This research aims to design and fabricate a solar kiln dryer that uses a solar panel to trap the sun's rich energy and also the design of an inverter that converts the direct current of the sun to an alternative current that will charge the battery and power heater element for drying. The principal mode of heat transfer is convection. The temperature of the incoming stream of air is raised by the heating element, a circular motion fan drives the heated air uniformly through the heating chamber, in this way heat is convectively transferred from the hot air to the cold air.

Wood is a hygroscopic material which gains moisture content as a result of changes in humidity. Hygroscopicity is one of the most distinctive properties of wood. Any kind of wood product absorbs and desorbs moisture from the surrounding air until it reaches equilibrium moisture content (EMC), a balance point between the wood's moisture content and that of the surrounding environment.

Fresh cut lumber contains a great deal of water. If the water is not removed, the lumber can't be used to produce a high quality finished product. Properly dried lumber sells for a higher price and is much easier to work with than lumber that have not been dried. When lumber is well dried it machines better, glues better, and finishes better. Drying also improves the strength of the lumber, kills infestations, hardens pitch, preserves colour, reduces weight and controls shrinkage. Lumber that is not dried under controlled conditions is prone to warping, staining, and other degradations that diminishes its selling price and workability.