Abstract
To improve the accuracy of the new in-process moisture content (MC) monitoring concept under radiofrequency/vacuum (RF/V) drying, equilibrium moisture content (EMC) tests were carried out under various ambient pressures, and pressure curves in wood were analyzed during chamber evacuation and heating phases. The results showed that EMC increased with a decrease in ambient pressure regardless of temperature, relative humidity (RH), and species. The accuracy of MC estimation for Hinoki under RF/V drying was improved from 1.5% maximum absolute errors to 0.6% after EMC modification. The pressure curves for Hinoki and Sugi under RF/V drying showed similar tendencies to an idealized process. Russian larch showed different curves, indicating that the pressure in the wood did not reach the ambient pressure because of its low permeability. Therefore, MC could not be estimated using this monitoring concept because of the presence of much air in the wood of Russian larch.
Article PDF
Similar content being viewed by others
References
Simpson WT (1987) Vacuum drying northern red oak. For Prod J 37:35–38
Koumoutsakos A, Avramidis S, Hatzikiriakos SG (2001) Radio frequency vacuum of wood. II. Experimental model evaluation. Dry Technol 19:85–98
Cai YC, Hayashi K (2007) New monitoring concept of moisture content distribution in wood during RF/vacuum drying. J Wood Sci 53:1–4
Chen ZJ, Fred ML (2002) Theoretical equilibrium moisture content of wood under vacuum. Wood Fiber Sci 34:553–559
Skaar C (1988) Wood-water relations. Springer, Berlin Heidelberg New York
Yi SL, Zhou YD, Liu YR, Zhang BG, Feng XJ (2008) Experimental equilibrium moisture content of wood under vacuum. Wood Fiber Sci 40:321–324
Carrier WH(1911) Rational psychometric formulae. Trans Am Soc Mech Eng 33:1005
Carpenter JH (1982) Fundamentals of psychometrics. Carrier Corp., Syracuse, p 57
Sasaki K, Kawabe J, Mori M (1987) Vacuum drying of wood with high frequency heating (II), the pressure within lumber during evacuation and drying (in Japanese). Bull Kyushu Univ For 57: 245–265
Kollmann FFP, Côté WA Jr, Wilfred ACJ (1968) Principles of wood science and technology I. Solid wood. Springer, Berlin Heidelberg New York
Author information
Authors and Affiliations
Corresponding author
About this article
Cite this article
Liu, H., Yang, L., Cai, Y. et al. Effect of EMC and air in wood on the new in-process moisture content monitoring concept under radiofrequency/vacuum (RF/V) drying. J Wood Sci 56, 95–99 (2010). https://doi.org/10.1007/s10086-009-1079-4
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10086-009-1079-4