Zone Modeling and Conservation Equations

It is important to distinguish between the mass loss or supply rate of the fuel and its burning rate within the compartment. The mass loss rate in contrast to Equation (11.23) is given as 

A typical transition to behavior of a ventilation-controlled fire begins with excess air as the fire feeds on the initial compartment air, but then is limited by air flow at the vent. As a consequence the fire can move to the vent and withdraw as the fuel is consumed. This might lead to two areas of deep burning if the fire is extinguished before complete burnout. 

The above discussion lays out the physics and chemical aspect of the processes in a compartment fire. They are coupled phenomena and do not necessarily lend themselves to exact solutions. They must be linked through an application of the conservation equations as developed in Chapter 3. The ultimate system of equations is commonly referred to as zone modeling for fire applications. There are many computer codes available that represent this type of modeling. They can be effective for predictions if the 

---