Locating the very early smoke detector apparatus (VESDA) in vertical laminar clean rooms according to the trajectories of smoke particles

Proper locating of a very early smoke detector apparatus (VESDA) in cleanrooms is an important issue for fire safety. The main aim of this study is to analyse the proper locations of a VESDA by determining the trajectories of smoke particles in the early stages from a fire in a vertical laminar flow clean room using computation fluid dynamics (CFD). The CFD model was first verified by experimental data of a reduced-scale clean room. Several influential factors on the trajectories of smoke particles including particle size, fire source temperature and fire location were then studied for a full-scale clean room. Results show that the fire source is the most notable factor influencing the trajectories of smoke particles. When the fire source was located at the centre of the room, the smoke particles travelled to the centre of the return air plenum (RAP). If the fire started close to the return air shaft (RAS), the smoke particles reached the RAP close to the top. If the fire started far away from the RAS, the smoke particles arrived at the RAP close to the bottom.