The curious case of the second/end peak in the heat release rate of wood: A cone calorimeter investigation

Abstract The reasons behind the occurrence of a second/end peak heat release rate (PHRR) during wood combustion under radiative heating were determined. Effects type rear material, thickness, char progression, and its microstructure, as well moisture content/transport in spruce wood, studied. Rear materials used insulating Kaowool, conducting steel, same but physically separated from test specimen by aluminium foil. intensity PHRR with Kaowool was almost 50% more than that sample steel. Thus, is governed boundary condition defined which determines losses at side consequently temperature specimen. Higher enhances pyrolysis rate, thereby causing PHRR. appearance times values for 30, 20, 10 mm 1740 s/78 kWm −2 , 685 s/134 450 s/160 respectively. Char progressed to samples even thin (8 mm) conductive steel substrate. Cracks grew three wider compared no peak. cracking had significance on time affected overall release. High content reduced charring delayed water needed undergo phase change, requiring higher amount energy.