Enhancing atomization and fire-Suppression efficiency of perfluorohexanone using swirl nozzles across a range of injection pressures

This study investigates the atomization, diffusion, and fire suppression performance of perfluorohexanone, discharged through a swirl nozzle in a 1 m³ sealed chamber, aiming to enhance the total flooding efficiency of this environmentally friendly Halon alternative. For the first time, the coupling effect of swirl nozzle geometry and injection pressure on droplet size distribution, vapor diffusion, and suppression effectiveness is systematically analyzed through combined experiments and computational fluid dynamics (CFD) simulations. Increasing the injection pressure from 0.3 to 0.5 MPa reduced D90 and D50 by 22 % and 29 %, respectively, which accelerated vaporization and improved the cooling rate. Correspondingly, the average chamber temperature declined from 25 °C to 7.2 °C, achieving a 49 % cooling efficiency improvement. Fire suppression time for upper-layer flames was reduced by 47 %, and the total flooding concentration was achieved within 3.3s, with CFD predictions closely matching experimental data. Lower nozzle heights improved suppression of near-ground flames, whereas higher positions enhanced coverage and atomization in upper layers. These results provide quantitative guidance for optimizing the design and deployment of perfluorohexanone total flooding systems in confined environments.