Hits:

Date of Publication:2022-10-06

Journal:Journal of Southeast University

Volume:23

Issue:2

Page Number:278-284

ISSN No.:1003-7985

Abstract:A two-dimensional and two-phase numerical model is presented for the smolder propagation in a horizontal polyurethane foam. The chemical processes considered include endothermic pyrolysis and exothermic oxidation degradation of polyurethane foam and exothermic oxidation of char. The governing equations are discretized in space using the finite element method and solved by the software package FEMLAB. Predicted profiles of solid temperature as well as evolutions of solid compositions (including foam, char and ash) are presented at an airflow velocity of 0.28 cm/s. The computed average smoldering velocity is 0.021 4 cm/s, and the average maximum temperature is 644.67 K. Based on the evolutions of solid compositions, the packed bed can be obviously divided into four zones: unreacted zone, fuel pyrolysis and oxidation zone, char oxidation zone and fuel burned-out zone. Simultaneously, the effects of inlet air velocity and fuel properties (including thermal conductivity, specific heat, density and pore diameter) are studied on the smoldering propagation. The results show that the smoldering velocity and temperature have a roughly linear increase with increasing inlet air velocity; the fuel density is the most important factor in determining smoldering propagation; radiation has a non-negligible role on the smoldering velocity for larger pore diameters of porous material. The computational results are compared with the experimental data and a general agreement is reached.

Note:新增回溯数据