Experimental investigations on ember- and radiation-coupled ignition in fuel beds

Experimental tests were conducted to examine the behaviour of ignition in ember and radiant heat-coupled ignition of common construction material fuel beds. Embers were deposited sequentially onto various fuel beds at an ember flux rate of similar to 2.1 pcs/min at various heat fluxes. Results show that ember and radiant heat-coupled conditions without a pilot had a slightly lower heat flux to flaming ignition of plywood compared to the critical heat flux for piloted flaming ignition value of previous studies. Increasing the initial radiant energy exposure time further decreased the critical heat flux for materials such as plywood, but for others, such as polyisocyanurate, the sample thermally decomposed, leading to a decrease in ignition probability.