The study of microwave absorption characteristics of sodium chloride in a novel quasi-optical cavity based on the parametric sensitivity analysis

Microwave assisted heating technology has become a popular alternative to conventional heating technologies with the characteristics of selectivity, instantaneity, integrity, safety, environmental friendliness and efficient energy-saving. Microwave absorption characteristics of material are critical because it provides an important index of utilization efficiency of microwave energy. However, a debate indeed exists on microwave absorption characteristics of material due to issues related to the non-homogenous field distribution, the energy utilization efficiency and lack of adequate optimization analysis, because of the parametric sensitivity and interdependence for microwave heating system. In this paper, a novel capsule-shaped cylindrical cavity based on the principle of quasi-optical resonator is designed for microwave heating and the dimension of the cavity is optimized programmatically based on the theory of pattern analysis to improve the uniformity of field distribution firstly. Then a series of high sensitive geometrical and material parameters are thoroughly investigated to optimize microwave absorption characteristics of sodium chloride in this novel quasi-optical cavity. The results demonstrate that the absorption of microwave energy for sodium chloride with different temperature and humidity is actually a dynamic variation process. Moreover, a fluctuating pattern of peaks and dips emerges in the graphs of temperature and humidity properties of sodium chloride and the capability to absorb microwave energy is dramatically dependent on the thickness of material. Therefore, it is possible to optimize these sensitive parameters to improve the microwave absorption characteristics and thereby to improve the energy utilization efficiency. Furthermore, when setting process parameters of sodium chloride, thickness at 0.01 m, 0.025 m, 0.075 m, moisture contents ranging from 2.5% to 5% and temperature ranging from 20°C to 60°C can be considered as the optimal technical parameters of sodium chloride in microwave heating.