ABSTRACT
FIRM-QB is a two-zone computer model that predicts the consequences of a user-specified f i e in a compartment with a single vent in a vertical wall. FIRM-QB is based on the assumption that the volume inside the compartment consists of a uniform layer of hot gases beneath the ceiling, and a layer of cold air between the floor and the hot layer. The main variables that are calculated as a function of time are upper layer temperature, layer interface height, and mass flows through the vent. The first two variables are estimated at discrete time steps by numerically solving the conservation equations of upper layer energy and lower layer mass. The conservation equations are ordinary differential equations (ODES) that are solved with a fourth-order Runge-Kutta technique with stepsize control. The vent flows are determined sirnultaneously by solving the compartment-wide mass balance equation. The bisection technique is used to solve this non-linear algebraic equation. The technical documentation of FIRM-QB is discussed in more detail in Chapter 5.
