The experimental and mathematical examination of timber drying

ABSTRACTMASTER THESISTHE EXPERIMENTAL AND MATHEMATICAL EXAMINATION OFTIMBER DRYINGFatma BAKIRFırat UniversityGraduate School of Natural and Applied SciencesDepartment of Chemical EngineeringTimber use has never lost its importance from ancient to today. However, themost of world forest has been under the threat of extinguishing for different reasons.This is because the source of wood has to be used in must efficient way and that causerequires to use high quality products in the wood industry. This can be onlyaccomplished by drying timber under the certain moisture value before its use.In this investigation, the most commonly used trees such as pine, beech, poplarand walnut in the world industry in our country were dried in trays drier at the constantvelocity and temperature of air. In order to perform experiments the five samples weretaken for each kind of timber. The variation of moisture loss, the rate of drying, heat andmass transfer coefficients with the drying time were examined experimentally. Asexpected it is observed that the moisture content decreases with increasing the dryingtime. The rate of drying, the heat and mass transfer coefficients decrease with increasingtime and thus decreasing moisture content. The heat transfer coefficients were obtainedin two different ways, that is, from the use of empirical equation that is derived from therule of heat given to sample has to be equal the heat taken by the evaporated moistureand from the use of Heissler diagrams for a slab. The obtained heat transfer coefficientsfrom the two different methods were compared with one another and it was observedthat the agreement between two heat transfer coefficients for the same sample is good.The optimum air velocity and of temperature previously determined were used in thedrying operations.Key Words: Drying, Timber, Heat transfer coefficient.