A Comparison Between FDS and the Multi-Zone Fire Model Regarding Gas Temperature and Visibility in Enclosure Fires

Abstract: When designing large buildings with complex geometry there is often a need for performance-based design and the use of computer models. CFD models like FDS that are available and validated for this purpose are typically time consuming and require large amounts of computing power. Zone models which are often faster and require less computing power are limited to simple geometries and smaller sized enclosures. The Multi-Zone Fire Model has been developed as an attempt to run less time-consuming simulations of large enclosures, but still with reasonable accuracy of the temperature and soot distribution in the enclosure. There have been previous efforts to produce models like this with multiple zones although limited to two dimensions while the Multi-Zone Fire Model, which is based on the same principals, is a three-dimensional model. The aim of this thesis has been to compare that newly developed model to FDS regarding gas temperature and visibility. The comparison is carried out by simulating a total of six scenarios, output data from measuring devices is then compared for each scenario. Results show that the Multi-Zone Fire Model can predict values which come close to simulated values from FDS for several of the simulated scenarios regarding both temperature and visibility. Like most models the MZ-model also has limitations that need to be considered before use and the process of comparing both models has highlighted some of the limitations and difficulties when setting up a simulation in the Multi-Zone Fire Model.