Simulation of car park fires using zone models

The fire environment in car parks of volumes varying from 2,000 m3to 50,000 m3, ceiling heights of 3 m, 4 m and 5 m are simulated using three fire zone models, namely CFAST and CCFM.VENTS developed at the Building and Fire Research Laboratory, NIST in U.S.A., and the NBTC one-room hot layer model of the fire engineers' calculator FIRECALC developed at the Division of Building and Construction, CSIRO, Australia. The model CFAST is found to be very suitable and the average hot gas temperatures predicted by it are correlated with the volume of the car parks. A time constant taking into account the size geometry and design fire is proposed to assess the fire risks of a car park. Ten local car parks of volume up to 50,000 m3are surveyed with the fire environment simulated. The derived correlation relation on the average hot temperature fits well with the volume and the time constant. The experimental data on small car park fires are also used to compare with the results predicted by these three zone models.