The term "heterogeneous" in this chapter is used loosely to refer to systems in which there are two phases. Under this classification, the subject of heterogeneous combustion is so broad that it is impossible to cover every aspect of it in this chapter. Therefore, only a limited selection of topics will be discussed: liquid droplet combustion, spray combustion, combustion of coal and coal-slurry particle, and smoldering combustion. As a reflection of the author's interest, emphasis will be on liquid droplet combustion and combustion of coal and coal-slurry particles. Discussions on other topics of heterogeneous combustion (e.g., combustion of metal particles, fixed-bed combustion, and fluidized-bed combustion) will not be included because of the voluminous amount of materials to be covered in this chapter.
Environmental Implications of Combustion Processes