Effect of dielectric properties on heat transfer characteristics of rubber materials via microwave heating

Abstract

The effects of dielectric properties on temperature distribution, heat flux density distribution, heating rate, heating efficiency and heating uniformity of rubber sheets via microwave heating were studied. Experimental and numerical simulation studies were carried out, the reliability of the simulation method was verified. The results demonstrated that the ability of rubber to absorb microwave energy and convert it into heat is significantly affected by dielectric constant and dielectric loss tangent. Different dielectric properties led to different electric field strength distributions in rubber sheets during microwave heating process, resulting in different electrical energy densities in the rubber sheets, eventually, different amounts of electric field energy can be converted into heat, resulting in different temperature distributions. The temperature distributions of rubber sheets are uneven. The temperature difference of rubber sheet increases with increasing heating time, but the growth rate of temperature difference decreases with increasing heating time. The higher the dielectric constant or loss tangent of rubber, the higher the microwave heating efficiency and temperature rise rate, but the more uneven the temperature distribution. The longer the heating time, the higher the average body temperature of rubber sheet, but the growth rate of the average body temperature decreases with increasing heating time. The heat flux density of rubber sheet was also significantly influenced by the dielectric properties, the maximum temperature gradient value is in the central area of the rubber sheet rather than in the hot spot area.