Application of microwave technology in wood processing and product testing in China

1.1 wood drying
Microwave drying is to use the high-frequency electromagnetic wave to make the polar water molecule in the wood swing frequently to heat the material. Heat is produced directly in the interior and distributes evenly. The temperature gradient and moisture gradient of the wood are small. It has the advantages of short heating time, good drying quality and high yield. After 40 years of development, wood microwave drying technology in China has formed a certain scale.

microwave drying equipment 

In the 1970s, the microwave drying equipment for wood was preliminarily studied in China. Meanwhile, the microwave drying technology was explored and the manufacturing technology of microwave equipment was preliminarily mastered. A wood microwave dryer has been developed in Nanjing No. 772 Plant and a large standing wave resonant cavity tunnel wood microwave dryer has been developed in Shanghai Changzheng Wood Products Factory. The application results of these two types of microwave dryers show that microwave drying can shorten the drying time by several dozen times, but the immature equipment and technology lead to wood cracking, deformation and other defects.

In the 1980s, experts in wood drying in China made some basic research on microwave drying technology, and summarized the basic technology of microwave drying wood. Tong Yonghui and others studied the relationship between microwave power, drying time, drying speed, moisture content and drying quality. It was found that drying speed and water loss rate increased with the increase of radiation power and time, but wood drying quality did not change in a certain extent. The microwave drying standard of resonant cavity dryer for common tree species and standard sawn timber was summarized by testing the production technology of microwave drying.

Microwave drying wood