Vacuum Drying of Sessile Oak (Quercus Petraea) with Alternative Heating Methods

Abstract

Aim of study: This study was prepared to determine the optimum drying process as a result of application of different parameters of vacuum drying method which is one of the technical drying methods, and to evaluate drying quality of these methods. Area of study: This study carried out at the Karabuk University in Karabuk, Turkey and the materials was obtained from the Karabük Yenice Forest Management Directorate. Material and Methods: Sessile Oak (Quercus Petraea) lumbers in 80x20x2.5 cm were dried at 2 m sec-1 air velocity using two different vacuum periods of 15 and 30 minutes, 2 different heating methods namely plated and IR (infrared) in the kiln were used. Ambient pressure was set at 300 mbar in vacuum periods and 800 mbar in heating periods. Main results: It was observed that the longest drying time was 242 hours (0.15%/hour) with drying in IR heating in 30 minutes periods and the shortest drying time was 126 hours (0.22%/hour) in IR heating with 15 minutes periods. It has been found that the drying time decreases with the decrease of the waiting time in the vacuum. It has been determined that while the drying methods with 15 minutes plated heating, 15 minutes IR heating and 30 minutes IR heating meet the standard (S) drying quality class requirements, drying made with 30 minutes plated heating has reached to the high quality (Q) drying class. Research highlights: IR heating in vacuum drying of Sessile Oak can be used successfully. Shorter vacuumheating periods leads higher drying rates in vacuum drying. Vacuum drying of lumbers wit IR heating meet the standard (S) drying quality class requirements.