Performance comparison of zone models with compartment fire tests

Prediction accuracy of zone models is attributed to the sophistication of the mathematical model, as well as the numerical methods applied in their implementation. Well-known zone models CFAST and OZone have gained world-wide acceptance among the fire engineering community in predicting enclosure fire dynamics. Despite these models serving similar purpose, the level of accuracy and applicability range are still a field of active research. This study compares an in-house developed zone model CFMFAN with CFAST and OZone in their modeling concepts, prediction capability, and accuracy. The sub-models for gas flow, heat transfer, and heat release rate are examined. Performance comparisons of these zone models with published experimental results for 20 single compartment fire tests are carried out in the blind mode. The test parameters used are the fire size (330980 kW) and the fire location (center or side). For performance comparisons, the upper- and lower-layer temperatures, interface and neutral plane heights, pressure difference at the floor, wall temperatures, plume flow, and vent flow rates are compared. Upon comparison with compartment fire test results, the study shows that CFAST consistently overpredicts the upper-layer temperature whereas OZone and CFMFAN underpredict it for all fire sizes. All the models underpredict the lower-layer temperature. Explanations are given for the deviations of the three models from the test results and from one another.