Dimension Optimization for Silica Sand Based on the Analysis of Dynamic Absorption Efficiency in Microwave Drying

We propose a theoretical guideline for prediction of maximum microwave absorption in microwave drying by optimizing the thickness of a silica sand layer based on analysis of reflection loss (RL). The microwave RL of the silica sand layer was studied over the moisture content of 1% to 5% at 20 degrees C and the silica sand (5% moisture content) in the temperature range of 20 to 100 degrees C at 2.45 GHz. The calculated RL for various moisture contents and temperatures shows that the RL sensitively depends on the thickness of the silica sand. There are absorption peaks in the RL patterns, and the microwave absorption peak shifts towards a smaller thickness side as the moisture content and temperature of the silica sand increase. We also show that the intensity of microwave absorption peaks in the RL patterns of silica sand decrease with decreasing moisture content, and achieve the highest absorption at 60 degrees C.