Effects of altitude and sample orientation on heat transfer for flame spread over polystyrene foams.

Experiments were carried out on insulation foams of EPS and XPS in a small-scale flame spread experimental bench in the Tibetan plateau area of Lhasa and the plain area of Hefei both in China, respectively. The effects of altitude and sample orientation on flame spread behavior were quantitatively analyzed. The results show that extinction and secondary ignition occur for XPS on plateau, as the oxygen concentration in air entrainment is influenced by the generated smoke in the pool fire zone. The flame spread speed of EPS increases with the incline angle both in Lhasa and in Hefei, but for XPS (downward flame spread), the flame spread speed increases with the decrease in incline angle, especially in Lhasa. It is found that the heat transfer process is different for EPS and XPS. The transition fire zone plays an important role in heat transfer over XPS for downward flame spread resulting in total heat transfer including the flame convective and radiative heat $$ q_{\text{f}}^{\prime \prime } \delta_{\text{f}} $$ and the conductive heat $$ q_{\text{c}}^{\prime \prime } L $$ increase with the decrease in incline angle, while for EPS, the surface flame zone dominates the heat transfer in two places. [ABSTRACT FROM AUTHOR]