ABSTRACT

Not every chemical oxidation reaction is considered to be combustion and not every combustion is accompanied by ames. A classication of different redox-reactions is given in Figure 23.1. Relatively slow redox-reactions with low intensity go on almost everywhere. Examples are rusting of steel, browning of a fresh cut apple, but also various reactions in the earth’s atmosphere. Combustion can happen naturally like a forest re that could be sparked by a lightning strike. Controlling combustion was one of the fundamental skills of mankind that allowed civilization. Most combustion processes involve ames that enable controlling combustion by visual examination. There are also some combustion processes that are not accompanied by ames. Catalytic surfaces can lower the activation energy for reactions and therefore enable reactions at lower temperatures without formation of ames. A campre will rst burn with blazing ames. Later on the ames will extinguish but reactions will still occur in the re bed until all char

is burnt to ash. Flameless combustion is therefore combustion in absence of ame [1].