This paper presents the results of a combined experimental and theoretical study of piloted ignition of cellulosic materials. The main objective is to present an engineering solution to the piloted ignition problem for wood exposed to radiant heat in a bench-scale piloted ignition test. This has been motivated by the need to have simple models of ignition for use in a computational fluid dynamics (CFD ) model of fire spread and extinguishment in building fires. The experiments were conducted on oven-dry and moisture conditioned samples of three wood species using a cone calorimeter. As expected, the experimental data revealed that the effect of moisture content on the piloted ignition process is significant. It was also found that the ignition temperature depends on the external heat flux, which supports other recent studies. Based on the experimental observations, an approximate analytical equation was derived and then used for correlating the ignition data, as well as extracting the piloted ignition properties. The chief distinguishing feature of the present equation over other similar equations is that it takes into account the variation of the ignition temperature with external heat flux. @~ 1997 Elsevier Science Ltd.
NOMENCLATURE C H~ h
Specific heat (kJ/kg K) Total surface heat loss rate(kW/m 2) Heat transfer coefficient (W/m 2 K)