A Two-Storey House: Temperature and Smoke Detector Activation with Various Fires Using the CFAST Fire Computer Code

摘要

A two-storey house with closed exterior door is considered with the Consolidated Fire and Smoke Transport CFAST computer code from NIST, with a variety of typical initial fires starting at the same location. All twelve predefined fires supplied in the CFAST software are used. Calculations are made of the smoke volume, temperature and location from typical developing fires, and the time to activation of smoke detectors is calculated. Sixteen smoke detectors in each of four rooms are included, with emphasis on the top three in each room, so as to illustrate the time required for their activation based on their position. In CFAST, each room of the structure is divided into two layers: these represent the upper and lower parts of the room, and conditions within each layer are taken to be homogeneous, this being based on experimental observation. Layer properties like thickness and temperature vary with time, and also vary from room to room. The distribution of the smoke in the rooms was visualized using Smokeview. Calculations included things like the upper and lower layer temperatures, the interface height, wall, ceiling and floor temperatures, and heat fluxes on to surfaces, and the time to activation of smoke detectors, depending on their location and activation criteria.