Numerical investigation of the flameless combustion mode of solid fuels

In this chapter, computational fluid dynamics (CFD) modeling of solid fuels combustion in the moderate- or intense-low-oxygen dilution (MILD) regime is presented. The general description of the pulverized solid fuels conversion is provided, and treatment of fuel conversion processes and typically used models to represent them is provided. Specifically, heating, drying, devolatilization, and char oxidation are discussed. This is followed by a discussion of modeling the turbulence-chemistry interaction in the gaseous phase and the formation and reduction of nitrogen oxides. The chapter emphasizes the differences between approaches used in the modeling of conventional and MILD combustion systems. The advantages and drawbacks of the currently available models are pointed out. References to CFD studies of solid fuels combustion in the MILD regime are provided, which include both small-scale experimental facilities and industrial-scale combustion chambers and boilers.