A feasible heat release rate estimation approach for fire hazard assessment in green design

Abstract

New energy harvesting systems in buildings are becoming more attractive in new green buildings. However, the potential fire hazard of the combustible items used in new green building limits their wider application. Fire behaviour of combustible items in new green designs should be studied carefully. Heat release rate of burning combustible items of different materials is important in fire hazard assessment and can be estimated by oxygen consumption calorimetry. An exhaust hood with a fan-duct system was built to collect flue gas. As the burning was likely to be incomplete in building fires, carbon monoxide, carbon dioxide, water vapor and soot would be emitted. Heat release rates of combustible items were estimated by measuring the transient amount of oxygen, carbon monoxide and carbon dioxide collected by the hood. Based on mass balancing, there are at least three equations in terms of mass flow rates of oxygen, carbon monoxide and carbon dioxide in the incoming air and exhaust gas. There are always questions about using which equations because measuring gases in full-scale burning tests is difficult and expensive. These three equations are introduced and compared in this paper. Heat release rates of four selected combustible items were studied as an example case. Accuracy of the results based on the measured oxygen concentration only was similar to the values provided by commercial software. Results from the experimental data are useful in further full-scale burning tests on combustible items in energy harvest systems planning at the moment.