Temperature Profiles In Forced-Ventilation Enclosure Fires

Abstract

We investigated the effect of ventilation rate, ventilation configuration , fire elevation, and the presence of a plenum (suspended ceiling) on the fire compartment temperatures during forced ventilated methane gas fires (100-400 kW). We found that with low air-inlet positions, fires with ventilation rates greater than 2-3 times the stoichiometrically required air (referred to here as well-ventilated fires) produce two-layer temperature profiles; fires with a lower ventilation rate (under-ventilated fires) produce single-layer profiles with a temperature gradient. Higher temperatures throughout the enclosure are seen in underven-tilated fires as compared to well-ventilated fires. We observed that high air-inlet locations perturb the two-layer temperature profile of the well-ventilated fire, cooling the upper layer and heating the lower layer. For underventilated fires, high air-inlet locations lower temperatures in the enclosure but do not perturb the profile shape. Elevated fires and fires in a compartment with a plenum were seen to behave similarly for the same distance from fire base to ceiling, producing hotter layers the shorter the distance.