Combustion models for biomass: A review

The present work seeks to review the current biomass combustion models in use for industrial applications. Combustion efficiency of coal fired boilers is a major concern for engineers and policy makers especially with the effect emissions have on the climate. Biomass, a renewable fuel, offers an alternative source of energy even when used in collaboration with coal. However, switching of fuel from coal to biomass on an industrial scale is an expensive task if taken up on an experimental basis. This leaves Computational Fluid Dynamics as a viable option for investigating the fuel switching at lower cost. This requires understanding of the numerical combustion models available. The combustion models presented are divided into particle drying models, devolatilization models, heterogeneous combustion and homogenous combustion. Other supporting models that are investigated are based on the particle tracking models, heat transfer models as well as turbulent models. The work is concluded with a summary of the industrial and laboratory applications that have used the models presented. As the models are numerous, trends can be drawn for the most common models as well as the reasons why they are used. Biomass combustion modelling is mainly influenced by the particle shape and the particle surface area under consideration during the combustion process.