CFDs Modeling and Simulation of Wheat Straw Pellet Combustion in a 10 kW Fixed-Bed Downdraft Reactor

Abstract

This research paper presents a comprehensive study on the combustion of wheat straw pellets in a 10 kW fixed-bed reactor through a Computational Fluid Dynamics (CFDs) simulation and experimental validation. The developed 2D CFDs model in ANSYS meshing simulates the combustion process in ANSYS Fluent software 2021 R2. The investigation evaluates key parameters such as equivalence ratio, heating value, and temperature distribution within the reactor to enhance gas production efficiency. The simulated results, including combustion temperature and produced gases (CO2, CO, CH4), demonstrate a significant agreement with experimental combustion data. The impact of the equivalence ratio on the conversion efficiency and lower heating value (LHV) is systematically explored, revealing that an equivalence ratio of 0.35 is optimal for maximum gas production efficiency. The resulting producer gas composition at this optimum condition includes CO (~27.67%), CH4 (~3.29%), CO2 (~11.09%), H2 (~11.09%), and N2 (~51%). The findings contribute valuable insights into improving the efficiency of fixed-bed reactors, offering essential information on performance parameters for sustainable and optimized combustion.