Study on Microwave Drying Characteristics of Wood Flakes

Change of moisture content(MC) and drying velocity characteristics of wood flakes, the influence of microwave power and flake form on the change properties of MC and drying velocity were studied by experiments with regular microwave drying, air oven drying and combined drying of microwave pretreatment and air oven drying. Per unit energy consumption(UEC)during microwave drying was calculated. The following results were obtained:The microwave drying saved about 80% of the time taken by air oven drying.The drying characteristics were significantly influenced by the microwave power, i.e., the greater the microwave power, the faster the drying velocity, the shorter the time consumed.The form of wood flakes influenced upon the microwave drying velocity, the bigger the surface area was, the more obviously the MC changed and the faster the drying velocity was.For energy efficiency, the optimal ratio of microwave power output and the sample mass was between 4~7 W/g.Microwave drying would cause charring damage to wood flakes by generating concentrative energy in the microwave field. Combination of microwave pretreatment with air oven drying could avoid charring damage in the microwave drying process, and realize the minimum target MC. Compared to traditional air oven drying, combination of microwave pretreatment with air oven drying could save about 70% of the drying time.