Temperature characteristics of wood during microwave treatments

In order to investigate the temperature characteristics of wood during microwave (MW) treatments, optical fiber sensors were used to measure wood ( Pinus sylvestris L. var. mongolica Litv.) temperatures. The results show that the development of internal temperatures in wood basically includes two patterns during the process of MW treatment. The first may be divided into three phases: warming, constant temperature, and a sharply rising phase. The second pattern may be divided into two phases: warming, and constant temperature. The maximum temperature (MT) and rate of temperature increase (RTI) rose as the microwave power increased. The initial wood moisture content decreased while the period of constant temperature fell. Temperatures varied in different positions in the wood. The order of MT and RTI levels were the upper surface, center, bottom surface and the end point. Along the direction of wood thickness, the closer the monitoring point was to the generator, the faster the temperature increased. The MT and RTI of the end point was a minimum value because of the rapid removal of steam.