Numerical study of liquefied petroleum gas (LPG) vapor cloud explosion in enclosed car parks

LPG (Liquefied Petroleum Gas) is gaining in popularity as an alternative choice of vehicle fuel since it is less costly and more environmentally friendly when compared with conventional fuels as gasoline and diesel. However, there are risks of LPG leakage from an LPG tank which leads to a VCE (Vapor Cloud Explosion) inside an enclosed car park. Pressure waves generated by the explosion may reflect on walls or in corners, leading to high overpressures. For this reason, vehicles equipped with LPG tanks are restricted from entering underground or enclosed car parks in Belgium and across Europe. This paper addresses this problem by using a CFD (Computational Fluid Dynamics) package to simulate the vapor cloud explosion inside an enclosed car park. The simulation was performed by using FLACS, which is a specialized commercial CFD package targeting at gas dispersion and explosion. The simulation was performed based on the geometry of a partially closed car park with the size of 30 × 30 × 2.4 m. Main structures like columns and ceiling beams as well as vehicles were modeled. The simulations of VCE determine the maximum overpressures as well as the development of the flame inside and outside the car park domain. Parameters studied in this paper are: the presence of vehicles and the vent openings of the car park. The main purpose of this paper is to provide some fundamental study in understand the consequence of an LPG vapor cloud explosion by looking into these parameters and their effects. The work presented in this paper is part of the project of a QRA (quantitative risk assessment) for enclosed car parks with vehicles equipped with LPG tanks. The results obtained in this early stage of the project were based on a 'worst-case' scenario by using a stoichiometric vapor cloud which is hardly probable under realistic circumstances.status: publishe