Numerrical modeling and design of a small scale timber drying kiln

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Syamunyangwa, Tanda
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Establishing Timber kilning plants requires substantial start up and subsequent operational investment costs, but the design of a small scale low cost kiln establishment would offer a possible solution to this. To achieve this, a numerical model of the drying chamber would first have to be developed and then a solid drawing of the kiln shell. A numerical and mathematical model was developed for simulating the drying process of a timber stack in a timber drying kiln. The model incorporates mass and heat transfer relationships within the kiln chamber, as well as mermodynamic properties of the wood,, drying air and the heat source. It takes into account a change of air properties along the stack and its effect on the mass and heat transfer parameters. Kiln parameters and wood board properties as well as a drying schedule are the input parameters that were defined and entered by a user. Experimentally determined values for the drying variables were used in the model input code PHOENICS Intel 2009. Validated variables used in this case included temperature, air velocity and pressure. The Model output showed that by reducing the size and altering the geometric profile of the kiln chamber and consequently reducing the drying variable gradients during the drying, you obtain a near constant drying rate. The timber stack dried under a heating chamber temperature of 80°celcius and average air velocity of 1.5 m/s. The model was validated against data available in the literature
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Engineering-Mathematical Model , Hydrology-Mathematical Model , Hydraulics-Mathematical Model