The characteristics of temperature near the ceiling of liquid fires in vertical laminar clean room environments

Numerical simulations of a clean room were conducted by software FDS5.3 using large-eddy simulation (LES). A computational fluid dynamics (CFD) model was first verified by comparing computational results with results of reduced scale clean room fire tests. The temperature near the ceiling round the fire location with three sizes acetone liquid fire were then studied for a typical full-scale clean room. Results show that the temperature near the ceiling is varied mainly due to the heat release rate (HRR). When the fire area is 0.5 m (meter) × 0.5 m, the excess temperature, near the ceiling in a horizontal distance 4.5 m from the fire centre, is below 50 K (Kelvin) during the whole process; when the fire area is 2.0 m × 0.5 m, the temperatures above the ambient (300 K), near the ceiling in a horizontal distance respectively 0.5 m and 2.5 m from the fire centre, get 50 K almost at the same time. However, under air ventilation, the temperature next to ceiling decreases fast with distance from the fire, so the radius of the smoke spread along the ceiling becomes small.