Upward Fire Growth over Thermally Thin Corrugated Paperboard

Abstract

A simple analytical model is developed for fire growth of thermally-thin corrugated paperboard in a parallel panel configuration that simulates the vertical flues between stored commodities in a rack storage arrangement. It is based on a semi-empirical model for radiation-dominated flame heat transfer to panels in terms of: (1) fuel flame sootiness, (2) fire heat release rates, and (3) panel width to separation aspect ratios. The model input properties include: heat of combustion, minimum heat of gasification, yield of smoke, and critical heat flux obtained from the fire propagation apparatus. The effect of moisture on fire growth rate is incorporated in the model. The predictions of the model are compared with experimental data on the rate of chemical heat release measured for the upward fire growth of vertical corrugated paperboard samples (0.305 m × 2.4 m) placed opposite one another in a parallel panel configuration (0.153 m apart). The model predictions of exponential fire growth time constant agree reasonably well with the experimentally determined values. Because of an enhanced role of convective heat transfer for parallel panels with 0.153 m separation distance, an adjustment of radiation constant β1 was needed for reasonable prediction of fire growth time constant. For a fixed geometry, the model prediction of fire growth time constant depends on the material properties and moisture content.