Thermal Energy Emission and Propagation from Accidents

Abstract

Many different kinds of accident may occur inside an industrial plant. Such events often produce, directly or indirectly, thermal radiation. The intensity of this radiation is frequently so high (for example, in fires and boiling liquid expanding vapour explosions — BLEVEs) that it causes significant damage to industrial installations or to people.

For industrial application, the calculation of the intensity of thermal radiation incident on a surface placed at a certain distance from a source is traditionally carried out by considering only the contribution of the radiation directly hitting the surface. Thus, in accident modelling, contributions due to radiation reflected from the ground, or absorbed by the ground and subsequently re-emitted, are neglected. The present work describes a model able to take into account these three contributions to the thermal radiation resulting from an accident.

The model calculates the energy re-emitted by the ground using a diffusion equation in one or two spatial dimensions. The space-time distribution of temperature, assuming the ground thickness is infinite both in depth and in extension, is estimated. The model is applied under different scenarios involving thermal radiation emission. The results show that the two contributions of thermal energy give additional effects that cannot be neglected in assessing risk exposure.