Dielectric properties and microwave heating characteristics of sodium chloride at 2.45 GHz

The effects of moisture content and temperature on the dielectric property of sodium chloride were investigated by using open-ended senor dielectric measurement system at the frequency of 2.45 GHz. Moisture content is a major influencing factor in the variation of dielectric properties. Dielectric constant, loss factor and loss tangent all increase linearly with moisture content increasing. Three predictive models were developed to obtain dielectric constant, loss factor, loss tangent and of sodium chloride as linear functions of moisture content. Temperature between 20 °C and 100 °C has a positive effect on dielectric constant and loss factor. Penetration depth decreased nonlinearly with moisture and temperature increasing. A predictive model was developed to calculate penetration depth for sodium chloride as a fifth function of moisture content. In addition, the measurements indicate that the particles temperature increases linearly with microwaving heating time at different power levels. The knowledge gained from these results is useful in developing more effective applications of microwave drying and designing better sensors for measuring moisture content of sodium chloride.