Investigation of the fire suppression capabilities of micromist water sprays

The proclamation of the Montreal protocol in 1987, phasing out ozone depleting halons as fire suppression agent has led to a worldwide research and development effort to find alternative systems. Water has clearly emerged as a potential replacement method to halons, mainly for its non-toxicity and low cost. Water sprinkler and water mist systems are widely used nowadays in fire protection. In a typical water mist the average droplet size is about 100 microns (few millimetres for sprinklers).

Past research studies have overlooked the potential of gas-like fine mist, called micromist (droplet size typically about 20 microns) for fire suppression. However, in recent years, there has been a worldwide renewed interest in micromist water systems for fire suppression for the following main reasons i) unlike water mist or sprinklers, gas-like micromist could reach the flame base hidden by obstacles, ii) micromist uses considerably less water than conventional water mist and sprinklers and 3) the relatively non-wetting nature of micromist means it is less damaging to equipment.

The main goal and novelty of the proposed PhD project is to investigate the fire suppression capabilities of fine micromist generated by flashing of superheated water through both experimental and theoretical methods. The key objectives are:

•          To conduct an extensive experimental study on the micromist fire suppression capabilities. The tests will be conducted in a reduced-scale fire testing compartment at Kingston University

•          To advance gas-like mist modelling and implement developed models in a large Eddy-Simulation CFD code (FireFoam) for flashing jet micromist/fire interaction study

•          To formulate recommendations on the fire suppression capability and viability of flashing micromist