摘要
雾给现代交通和人类身体健康造成严重影响,人工消雾对于防灾减灾具有重要价值。但目前关于消雾机理仍存在一定争议,关于催化剂粒径的选择也具有较大不确定性。本研究基于15 000 m3大型雾室,开展了不同粒径催化剂颗粒对暖雾清除效果的研究。结果表明:A催化剂(粒径为75μm)具有良好的消雾能力,消雾时间约为自然沉降的20%;B催化剂(粒径为100μm)消雾时间约为自然沉降的40%,消雾效果相比A催化剂偏差。为验证和计算最优催化剂粒径,本研究利用重力连续碰并增长模型,从理论上分析了消雾催化剂的最优粒径。结果表明:催化剂颗粒过小,捕获的雾滴少,碰并耗水少,消雾时间长;催化剂颗粒过大,下降速度快,消雾时间短,但捕获的雾滴少,碰并耗水少。综合来看,最优的催化剂颗粒直径为40~80μm。本研究结果可为外场消雾试验提供科学参考。
Heavy fog significantly impacts modern transportation and public health.Thus,artificial fog dispersal crucial for disaster prevention and mitigation.Despite its importance,the mechanism underlying fog dispersal and the optimal particle size of dispersal catalyst remains uncertain.This study,conducted in a 15000 cubic meter cloud chamber,explores the influence of different catalyst particle sizes on warm fog clearance.We found that catalyst A,with a particle size of 75μm,effectively reduced the number concentration of fog droplets from 5800 g/cm 3 to 2000 g/cm 3 within 8 minutes and further to 1000 g/cm 3 within 10 minutes,while decreasing the liquid water content from 2.45 g/m 3 to 0.2 g/m 3.The mean volume diameter of the fog droplets increased from 6—8μm to 10—20μm,accelerating the fog clearance to 20%of the time required for natural sedimentation.In contrast,Catalyst B(with a particle size of 100μm)induced raindrop formation under heavy fog conditions,clearing the fog in 40%of the time taken by natural sedimentation,albeit with slightly less effectiveness than catalyst A.To determine the optimal catalyst particle size,we employed a gravitational continuous collision and growth model to evaluate the fog dispersal efficacy of different particle sizes,providing a theoretical basis for selecting the most effective size.Theoretical calculations suggest that for a droplet radius of 6μm in a 25 m high cloud chamber,the collision efficiencies catalyst particles sized 50μm and 100μm are comparable(approximately 80%),requiring a catalyst mass of 3.52 kg.However,the dispersal for 50μm radius particles is twice as long as for 100μm particles.The study indicates that for droplets radii of 6—15μm,catalyst particles in the 60—100μm range are most effective.Further analysis revealed that excessively small catalyst particles capture fewer fog droplets,require more time for fog dispersal,and consume less water during collisions.Conversely,overly large catalyst particles clear fog faster and have higher descent speed but are less effective in water consumption and droplet capture.Therefore,an optimal catalyst particle diameter of 40—80μm is suggested.The findings presented here are based on a simplified gravitational continuous collision and growth model and do not consider factors such as vertical velocity and variations in liquid water content with height.Future studies should address these to refine the theoretical mechanisms of fog clearance and improve catalyst dosage calculations.
作者
郑鹤鹏
解妍琼
张云
余婷
黄梦宇
田平
毕凯
丁德平
余昊翔
葛攀延
ZHENG Hepeng;XIE Yanqiong;ZHANG Yun;YU Ting;HUANG Mengyu;TIAN Ping;BI Kai;DING Deping;YU Haoxiang;GE Panyan(College of Meteorology and Oceanography,National University of Defense Technology,Changsha 410073,China;College of Advanced Interdisciplinary Studies,National University of Defense Technology,Changsha 410073,China;Beijing Weather Modification Center,Beijing 100089,China;Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters/Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration,Nanjing University of Information Science and Technology,Nanjing 210044,China)
出处
《大气科学学报》
CSCD
北大核心
2024年第4期620-628,共9页
Transactions of Atmospheric Sciences
基金
国家自然科学基金资助项目(42075080)。
关键词
大型雾室
消雾试验
吸湿性催化剂
重力连续碰并增长模型
能见度
large-scale cloud chamber
fog elimination test
moisture absorbent catalyst
gravitational continuous coagulation and growth model
visibility
