Fire chemistry is the study of chemical process that occur in fires, including changes of state, decomposition, and combustion. Phases changes most relevant in fire are melting and vaporization. There is no change in chemical structure during these phase changes. Thermal decomposition, however, involves irreversible changes in the chemical structure of a material due to the effect of heat. This process is known as pyrolysis and it generally produces gases.

Heat transfer is defined as the transport of heat energy from one point to another caused by a temperature difference between those two points. Unless work is being done on the system by outside forces, heat is naturally transferred from a higher temperature mass to a lower temperature mass. The three heat transfer are conduction, convection, and radiation.

Conduction is a form of heat transfer that takes place within solids when one portion of an object is heated. Energy is transferred from the heated area to the unheated area at a rate dependent on the difference in temperature and the thermal conductivity of the material.

Convection is the transfer of heat energy by the movement of heated liquids or gases from the source of heat to a cooler part of the environment. In the early part of a fire, convection plays a major role in heating the surfaces exposed to gases heated by the fire.

Radiation is the transfer of heat energy from one hot surface or gas, the radiator, to a cooler material by electromagnetic waves without the need of an intervening medium. Radiation explains flashover.

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