Study on flashover in small residential units with an open kitchen by nonlinear dynamics

Abstract

Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.

Flashover is a dangerous phenomenon in building fires which is characterized by a sharp increase in burning rate and gas temperature. Open kitchens have been designed for many small units in tall residential buildings in densely populated areas, sparking big concerns about fire safety because of its small confined area and high fire load density. Efforts on preventing flashover should be made. In this paper, nonlinear dynamical system was used to study flashover in an example apartment with an open kitchen. A two-layer zone model was used to simulate the apartment fire by a hot upper smoke layer and a cool lower layer. The hot smoke layer temperature was taken as a single state variable in the model. The rates of heat gain from the fire and heat loss from the smoke layer were expressed as functions of temperature. A differential equation was set up to describe the rate of change of the layer temperature based on a simple heat balance of the smoke layer. Evolution of the smoke layer temperature, equilibrium states of the system and their corresponding stabilities were then investigated. The heat release rate was taken to be one of the most important control parameters affecting the evolution of the system state. The impacts of different heat release rates on the system state were studied. Critical conditions for the onset of flashover obtained from this model were compared with data available in the literature.