Abstract
A superheated steam dryer (SSD) was used to dry the parawood. The average moisture content and temperatures in the dryer vs. elapsed drying time were experimentally investigated. It was found that the superheated steam could increase the potential of the conventional hot air drying. By using a SSD at the superheated steam temperature of 110 ?C with volumetric flow rate of 125 m3 min?1 for parawood's thickness of about 30 mm, the moisture content of the parawood could be reduced from 40% (d.b.) to about 9.75% (d.b.) within 35 hrs while the conventional hot air dryer required the drying time of approximately 8-16 days. The physical structure of the parawood was also investigated by a prong test. The quality of dried parawood was not found to be different from those dried with the hot air drying method.
Highlights
Over the years, the application of superheated steam for drying have been studied by a number of researchers[1,2,3,4,5,6,7,8,9,10,11]
Comparison between superheated steam drying and hot air drying: Figure 11 shows a relationship between average moisture content and elapsed drying time of superheated steam drying at the temperature of 110 °C, flow rate of 125 m3 min1, compared with hot air drying at the air temperature of 40 °C, relative humidity of 70%
Effect of wood’s thickness: As shown in Fig. 9, at the blower delivery of 125 m3 min1, it was found that the wood of 25mm thickness yielded maximum moisture
Summary
The application of superheated steam for drying have been studied by a number of researchers[1,2,3,4,5,6,7,8,9,10,11]. There are few studies applying the superheated steam with the wood drying. Pang and Pearson[10] conducted an experiment to dry radiate pine timber by using superheated steam under vacuum and at various pressures. Experimental studies were performed to investigate the applications of the superheated steam drying at ultrahigh temperatures. In order to have fully understanding of the wood drying process using superheated steam, more experimental studies on this issue should be done. The effects of superheated steam temperature, flow delivery and wood thickness on the drying kinetics were investigated and compared.
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