Discussion on heat lost through solid boundaries in modeling atrium fires under mechanical exhaust

Mechanical smoke exhaust systems are usually required in large atria in the Far East. Systems are designed based on empirical expressions in the literature. Most of those design equations were derived from a two-layer zone modelling approach under some geometrical restrictions. Full-scale burning tests on mechanical smoke exhaust system were carried out. From these experiments, it was found that there are significant differences between the measured results in some of the tests and those calculated from the design equations using a two-layer approach. Mass exchange through the smoke layer and cool air layer was identified earlier to be a key point under some conditions. But heat lost through the solid boundaries is another factor as pointed out recently. This point will be further discussed in this paper. A simple model based on a two-layer approach reported earlier will be applied to justify those design equations and experimental results. Selection and peer-review under responsibility of the Asia-Oceania Association for Fire Science and Technology.