Secagem da madeira de Hovenia dulcis e Eucalyptus tereticornis em forno micro-ondas com diferentes potências de temperatura

Abstract

Microwave drying of wood is recent in Brazil, requiring more research to improve knowledge and dissemination of this technology. The objective of this study is to evaluate the drying of the wood in a microwave oven with different temperature powers and to compare its use in the water removal process in Hovenia dulcis and Eucalyptus tereticornis. Samples were subjected to microwave drying with 50% or 100% power level. Moisture content, drying rate and moisture gradient were evaluated. Hovenia dulcis, even with a higher initial moisture content, reached the final moisture content in less time. The drying rate for this species was also higher (0.89 at 100% power level, compared to 0.22 for E. tereticornis) indicating that water flows quickly, even with the wood presenting more than twice the humidity in relation to the E. tereticornis. Moisture gradients for Eucalyptus tereticornis showed negative values, indicating that the inside of the analyzed wood pieces (-1,36 in 100% and -1,63 in 50% power level) were drier than the outside (-1,82 in 100% and -1,88 in 50% power level), reflecting one of the main characteristics of microwave drying, which is heating from the inside out, generating heat directly in the center of the wood. Regardless of the power level used, Eucalyptus tereticornis wood presented greater difficulty in drying compared to Hovenia dulcis.