Dielectric properties and microwave heating of oil palm biomass and biochar

The conversion of the electromagnetic energy into heat depends largely on the dielectric properties of the material being treated. Therefore, the fundamental understanding of these properties is necessary for designing industrial microwave processing unit. The objective of this study is to investigate the dielectric properties of oil palm biomass and biochar at varying frequency in the range 0.2-10 GHz. The dielectric properties were measured using a coaxial probe attached to a network analyzer. The results indicate the dielectric constant was found to be inversely proportional to the frequency. However, the biomass in the present study did not obey the famous Debye equation and hence, the loss factor was found to be directly proportional to the frequency. The dielectric properties of oil palm shell (OPS) and its biochar were found to be almost similar and higher than oil palm fiber (OPF). Relaxation time and static dielectric constant were also presented in the paper. Lastly, the heating characteristics under MW irradiation confirmed poor microwave absorbing properties of oil palm biomass. (C) 2013 Elsevier B.V. All rights reserved.