What process liberates gaseous fuel vapors due to the heating of a solid fuel?

The process that liberates gaseous fuel vapors due to the heating of a solid fuel is known as pyrolysis. This is a thermal decomposition process that occurs when organic materials (like wood, plastics, or other solid fuels) are heated to high temperatures in the absence of oxygen. As these materials heat up, they break down chemically, resulting in the production of gases, liquids, and solid char. Pyrolysis is critical in the context of fire behavior because the gaseous fuels produced during this process can contribute significantly to ignition and combustion.

In contrast, combustion refers to the overall chemical reaction that occurs when a fuel reacts with oxygen to produce heat and light, but does not specifically focus on the vaporization of solid fuels. The flash point is the lowest temperature at which a liquid can vaporize to form an ignitable mixture in air, and vaporization pertains to the phase change of a substance from a liquid to a gas, rather than from a solid. Thus, pyrolysis is uniquely defined by the transformation of solid fuel into gaseous fuel vapors through heating.