CFD Modelling of LPG Dispersion in a Road Environment

Inland transportation of Liquified Petroleum Gas (LPG) is often carried out using road tankers. An accident during road transport may lead to an unintended discharge of LPG on the road, which could mix with the surrounding air to form a flammable fuel-air cloud. This cloud is normally characterized by an irregular shape and non-uniform concentration, depending on factors such as geometrical and meteorological conditions and the properties of the leakage. Furthermore, the presence of vehicles on the road may significantly affect the dispersion and concentration of the cloud and may cause partial confinement or obstruction of the cloud, which could potentially become a source of dangerous gas explosions on the road. This paper presents a numerical study of dispersion of LPG in a road environment following an unintended leakage from a road tanker. The work was conducted using the computational fluid dynamics (CFD) code FLACS-CFD. The purpose was to quantify the extension of the gas cloud within the flammability limits for different leak properties, wind conditions, and traffic layout. For each case, an equivalent gas cloud with a regular shape and stoichiometric concentration was determined using the Q9 cloud model. Based on the results, recommendations for the choice of equivalent gas volume for different standard scenarios are presented.