CFD-based study and analysis on the effectiveness of water mist in interacting pool fire suppression

Abstract

Accidental fires result in extensive loss of property, damage to the environment and a large number of fatalities every year. When fuel collects in the form of a pool and burns, it is termed a pool fire. Pool fires may burn in isolation – Non-interacting or as Single Pool Fires (SPFs) – or flames from multiple pool fires may interact with each other and burn in what is termed as Multiple Pool Fires (MPFs). Even as single pool fires (SPFs) are difficult to control, interacting flames due to multiple pool fires (MPFs) are even more difficult to extinguish. Compared to SPF, MPFs tend to have much higher flames and are reported to have extraordinary thermal intensity. Accidental pool fires in warehouses, commercial and residential buildings may interact, giving rise to interacting pool fires (MPFs). The commonly used technique to suppress fires in enclosures such as warehouse, commercial or residential buildings is to use sprinklers. Hence, this study reports the numerical simulations performed to analyse the effectiveness of water-mist sprinklers in extinguishing MPFs. The related CFD coding and simulations were performed using Fire Dynamics Simulator (FDS), FDS tools like Pyrosim (pre-processor) and Smokeview (post-processor) packages. The effect of the ratio of the separation distance between the pools (S) to the diameter (D) on the overall fire suppression efficiency of the water-mist sprinkler as a function of the water mist flow rate, the height of the ceiling, and sprinkler particle size are vigorously analysed in this work. The analysis presented in this article will mainly help to resolve problems associated with the effectiveness of mist-sprinkler in warehouse fires regarding process safety viewpoint.