Experimental investigation and numerical modelling of CO and HCN release during the combustion of flexible polyurethane foam

Abstract

The combustion of flexible polyurethane foam (FPUF) in fires releases relatively large amounts of carbon monoxide (CO) and hydrogen cyanide (HCN), threatening the lives of those exposed thereto. It is therefore necessary to use computational fluid dynamics method to explore the distribution of CO and HCN in a fire involving the combustion of FPUF. However, the release of CO and HCN varies significantly with the combustion conditions, which makes the numerical modelling challenging. In the present research, the yields of CO and HCN during the combustion of a non-flame-retardant FPUF were determined using a steady-state tube furnace (SSTF) facility, considering the effect of the ventilation condition. Meanwhile, a pyrolysis and combustion model of FPUF was constructed based on the fire dynamics simulator (FDS), and a four-step chemistry model was proposed to deal with the reactions in the gas phase. The experimental results showed that the yields of CO and HCN both increased with the limitation of ventilation, which was more pronounced in under-ventilated conditions. Meanwhile, the numerical simulation applying the four-step chemistry model predicted the variations in the yields of CO and HCN under ventilated conditions. In addition, when the appropriate kinetic parameters were applied to the reactions governing the oxidation of CO and HCN, the comparative results indicated that the global average deviations between the predicted and experimental yields could be reduced to 13.61 % (CO) and 8.19 % (HCN), respectively.