Optimization analysis of influencing factors of water mist system in utility tunnel based on orthogonal tests

The utility tunnel is distinguished by its elongated and confined geometry, which exacerbates the rapid propagation of fire in the event of an incident. Minimizing the adverse impact of a power cable fire on the electricity supply to adjacent residents is of utmost importance. In this paper, the orthogonal test method was employed to investigate the sensitivity sequence of four factors influencing fire suppression in utility tunnels, specifically analyzing the suppression efficacy of a fine water mist system on cable fires within utility tunnels. Subsequently, the accuracy of the numerical simulation was validated by comparing with an experimental case study. The results showed that the sensitivity order of the fine water mist system to the temperature of a utility tunnel fire is as follows: nozzle flow coefficient, ventilation conditions, droplet size, and initial droplet velocity. Furthermore, sensitivity analysis unveiled that an optimal combination of these factors can significantly enhance suppression efficiency. Specifically, the optimal combination of fine water mist parameters led to a 64.33 % increase in extinguishing efficiency compared to the average value. Lastly, this paper put forward recommendations to augment the cable compartment fire suppression system, thereby fostering conditions conducive to the safe operation of the cable compartment. The results presented in this paper provide valuable insights for the optimized design of the fine water mist fire suppression system in the cable compartment of utility tunnels, serving as a benchmark for future research endeavors in this domain.