Research on optimizing liquid nitrogen fire extinguishing efficiency in urban underground logistics systems through enhanced longitudinal ventilation
Fire suppression systems commonly used in narrow and confined spaces have limitations when applied in urban under-ground logistics systems,making them difficult to implement di-rectly.To investigate the improvement in liquid nitrogen extin-guishing efficiency under the influence of enhanced longitudinal ventilation in urban underground logistics systems,this study ana-lyzes the changes in oxygen volume fraction and ceiling tempera-ture under different working conditions by varying wind speed and nitrogen injection position.The results indicate that nitrogen injec-tion can effectively extinguish fires in underground logistics tun-nels,and enhanced longitudinal ventilation significantly improves the extinguishing efficiency of liquid nitrogen.When the nitrogen injection distance is 50 m,the extinguishing efficiency under a wind speed condition of 2 m/s is increased by 41.86%compared to a wind speed condition of 0 m/s.Additionally,at a fixed nitro-gen injection distance,enhanced longitudinal ventilation signifi-cantly advances the time when the temperature and oxygen vol-ume fraction near the fire source begin to decline.Moreover,as the nitrogen injection distance increases,the time for the tempera-ture and oxygen volume fraction near the fire source to decline is delayed;however,enhanced longitudinal ventilation can mitigate the lag in cooling and asphyxiation effects caused by the increased injection distance.These findings provide important theoretical support for fire suppression research in urban underground logis-tics systems.
万方数据
维普
