Experimental and Numerical Investigation on Ignition and Horizontal Flame Spread for Recycled Plastic Pellets

Abstract

Fires in recycling facilities are known for producing noxious fumes, having high heat release rates (HRRs), being difficult to extinguish and causing significant devastation to business operations. This research aims to provide experimental data and numerical models from which performance-based designs can be developed for recycling facilities. Through validating simulation models against experimental data, ignition parameters are verified and can be used as inputs for future larger-scale modelling of flame spread and behaviour. In previous research, cone calorimeter tests were conducted in which the thermal properties (HRR curves, heat of combustion [HOC], time to ignition [TTI]) of recycled plastic pellets were determined. In this research ignition and flame spread are studied, which includes flame spread experiments in a horizontal trough. This data is used to calibrate the density, thermal conductivity, and specific heat capacity by comparing the TTI observed from cone calorimeter testing to that observed in simulated models. The HRR curves and HOC, in addition to the calibrated density, thermal conductivity and specific heat capacity, are used for fire dynamic simulator (FDS) models presented in this paper to simulate and observe the horizontal flame spread rate of shallow samples of plastic pellets made of recycled material. This paper then compares experimental and numerical horizontal flame spread rates and burning behaviour observed. The experimental and simulated horizontal flame spread rates are in the same order of magnitude, 0.2 and 0.35 cm/min respectively, highlighting that the ignition, initial flame spread and model parameters have been suitably captured.