Effects of sample orientation on pyrolysis and piloted ignition of wood

In this work, the pyrolysis and piloted ignition behavior of thermally thick paulownia wood brick for different orientations has been experimentally investigated, by using the conical heater. Three typical orientations were adopted, that is, upward, downward, and vertical cases with the incident heat flux ranging from 12 to 39 kW/m(2). A numerical approach was used to test the effect of heat convection and radiation blockage on pyrolysis. The ignition time was observed to be strongly dependent on orientation. In detail, the shortest ignition time turns to be for downward orientation, but longest ignition time for vertical orientation. Total mass loss at ignition is weakly dependent on orientation. Meanwhile, critical mass flux increases with external heat flux rising and varies somewhat with orientation.