Froude-Stanton modeling of heat and mass transfer in large vertical spaces of high-rise buildings

Understanding physics of heat and mass transfer inside large vertical spaces is a major challenge for high-rise fire safety. Due to the size of a high-rise building, experimental studies based on sub-scaled models play an important role in high-rise heat and mass transfer research. Froude modeling method is probably the most common approach for sub-scaling. However, Froude modeling has been found incapable of obtaining accurate temperature predictions from the sub-scaled experiments, especially near building boundaries where there exists significant heat transfer between smoke and the boundaries. In this paper, a new modeling method, Froude-Stanton modeling, is developed for both mechanically-driven and naturally-driven thermal smoke spreads, in which heat transfer is taken into consideration in the energy balance equation. The flow resistance of the internal shaft structure is also considered using a lumped method. To verify the new method, series of experiments were conducted on three shafts with different sizes and material using both Froude and Froude-Stanton methods. The results, including temperature profile, relative neutral plane level and thermal smoke flow rate, are compared between the two modeling methods, and it was found that the new Froude-Stanton modeling method is more accurate.