Simulation studies on microwave-assisted pyrolysis of biomass for bioenergy production with special attention on waveguide number and location

The society's concern has moved toward sustainability nowadays and hence, the conversion of biomass into biofuels, through pyrolysis process, is one of the current research trends. Green processing technologies, like microwave heating, has been suggested to replace the conventional heating for biomass conversion as it provides energy-efficient heating and reduces time consumption. In this work, COMSOL Multiphysics software was used to study the effects of the waveguide position (bottom-fed vs side-fed) and unit (single-fed vs double-fed) on the electromagnetic field and heat distribution profile within the sample. Based on the results, the double-fed microwave can achieve higher maximum temperature (462 °C) at the same simulation time, followed by the single bottom-fed reactor (404 °C). An extension to the investigated work with more than two waveguides has shown that it will neither improve the electric field distribution nor increase the maximum temperature. This work concludes that both the position and unit of the waveguide are highly influential factors in determining the quality and speed of the biomass heating process. The double-fed microwave is the most suitable design to accelerate the pyrolysis process. The assumption of this simulation study is further validated as there is only ∼5% difference between simulations and experiments.