1 theoretical analysis of the causes of defects in wood microwave drying
Theoretically, the causes of wood drying defects during microwave drying are mainly reflected in the following three aspects: First, wet wood is a typical anisotropic heterogeneous material. In microwave field, the microwave energy absorbed by different parts of wet wood can be expressed in the following way:
P =k fE 2 epsilon r TG Delta (W/m 3)
Theoretically, the causes of wood drying defects during microwave drying are mainly reflected in the following three aspects: First, wet wood is a typical anisotropic heterogeneous material. In microwave field, the microwave energy absorbed by different parts of wet wood can be expressed in the following way:
P =k fE 2 epsilon r TG Delta (W/m 3)
microwave drying
In the formula: K is a constant; f is a microwave frequency (Hz); E is an electric field strength (V/m); epsilon R is a dielectric constant of wet wood; TG delta is a tangent of loss angle (or loss factor) of wet wood.
It can be seen from equation (1) that the ability of wet wood to absorb microwave (or convert microwave energy into heat energy) depends on the dielectric constant, loss factor, microwave frequency and field strength of wet wood. The absorption ability of wet wood to microwave depends entirely on the dielectric constant (dielectric constant and loss factor) of wet wood when the microwave field intensity and frequency are constant.
Wet wood is a typical anisotropic heterogeneous biomass material. Within the wood, there are differences in wood properties between early wood and late wood, heartwood and sapwood, and significant differences in moisture content in different parts of the wood, resulting in differences in dielectric properties between different parts of the wood, making different parts of the wood. The temperature difference is caused by the different ability of absorbing microwave.
In the formula: K is a constant; f is a microwave frequency (Hz); E is an electric field strength (V/m); epsilon R is a dielectric constant of wet wood; TG delta is a tangent of loss angle (or loss factor) of wet wood.
It can be seen from equation (1) that the ability of wet wood to absorb microwave (or convert microwave energy into heat energy) depends on the dielectric constant, loss factor, microwave frequency and field strength of wet wood. The absorption ability of wet wood to microwave depends entirely on the dielectric constant (dielectric constant and loss factor) of wet wood when the microwave field intensity and frequency are constant.
Wet wood is a typical anisotropic heterogeneous biomass material. Within the wood, there are differences in wood properties between early wood and late wood, heartwood and sapwood, and significant differences in moisture content in different parts of the wood, resulting in differences in dielectric properties between different parts of the wood, making different parts of the wood. The temperature difference is caused by the different ability of absorbing microwave.
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