Air filters with a low resistance,high filtration efficiency,and long lifetime are important to ensure good indoor air quality.In this study,the lattice Boltzmann method is applied on six types of fibrous filter media...Air filters with a low resistance,high filtration efficiency,and long lifetime are important to ensure good indoor air quality.In this study,the lattice Boltzmann method is applied on six types of fibrous filter media with lognormal-distribution models,which consider the influence of the solid fraction,number of fibers,and average fiber diameter.The influences of the filtration velocity and fiber layout on the resistance,efficiency,and quality factor are discussed.The resistance is found to be relatively low when the solid fraction inside the filter media is uniformly distributed.The filter media with a random lognormal-distribution model demonstrated the best filtration performance in terms of quality factor.However,when the solid fraction is uniform along the thickness of the filter media,the comprehensive filtration performance is the best when a small fiber is near the inlet and a large one is close to the outlet.This study provides a viable numerical method for performance optimization of air-filtration devices for the next-generation cleanroom industry.展开更多
Rapid increase of urban underground constructions has a great consideration of underground environment safety and how to expel toxic gasses out of tunnels effectively.The utility tunnel is a typical urban tunnel const...Rapid increase of urban underground constructions has a great consideration of underground environment safety and how to expel toxic gasses out of tunnels effectively.The utility tunnel is a typical urban tunnel construction with multiple underground pipelines including gas pipelines,and it is necessary to investigate characteristic of gas diffusion and monitor gas leakage to ensure tunnel safety.In this study,the experimental measurements of airflow and gas distributions were conducted in a 10 m full-scaled utility tunnel mockup,and gas diffusion characteristic was also investigated.Numerical simulation of utility tunnel leakage was also conducted by computational fluid dynamics(CFD).Different turbulence models and different air supply diffuser models were compared via the experimental results based on visualization and the relative root-mean-square error(RRMSE)index,which quan-titated the difference between the numerical and experimental results.The results showed that the standard k−εturbulence model and random air opening model could provide better results than other models.According to the experimental data analysis,it was necessary to consider the optimization of monitoring detector arrangements in actual utility tunnels.This study provided basic experimental data and the validated numerical model for the leakage source identification and underground tunnels simulation research.展开更多
基金This work is financially supported by the National Natural Science Foundation of China(No.51508267)the Six Talent Peaks Project of Jiangsu Province(JNHB-043)+2 种基金the Natural Science Foundation of Jiangsu Province(No.BK20130946)Postgraduate Research&Practice Innovation Program of Jiangsu Province(SJCX20_0324)the Scientific Research Foundation from Nanjing Tech University(No.44214122).
文摘Air filters with a low resistance,high filtration efficiency,and long lifetime are important to ensure good indoor air quality.In this study,the lattice Boltzmann method is applied on six types of fibrous filter media with lognormal-distribution models,which consider the influence of the solid fraction,number of fibers,and average fiber diameter.The influences of the filtration velocity and fiber layout on the resistance,efficiency,and quality factor are discussed.The resistance is found to be relatively low when the solid fraction inside the filter media is uniformly distributed.The filter media with a random lognormal-distribution model demonstrated the best filtration performance in terms of quality factor.However,when the solid fraction is uniform along the thickness of the filter media,the comprehensive filtration performance is the best when a small fiber is near the inlet and a large one is close to the outlet.This study provides a viable numerical method for performance optimization of air-filtration devices for the next-generation cleanroom industry.
基金This study supported by the National Natural Science Foundation of China(Grant No.51708286)the Natural Science Foundation of Jiangsu Province(No.BK20171015)+1 种基金The study was also supported by the National Natural Science Foundation of China(Grant No.51478468)the National Natural Science Foundation of China)No.51978166.
文摘Rapid increase of urban underground constructions has a great consideration of underground environment safety and how to expel toxic gasses out of tunnels effectively.The utility tunnel is a typical urban tunnel construction with multiple underground pipelines including gas pipelines,and it is necessary to investigate characteristic of gas diffusion and monitor gas leakage to ensure tunnel safety.In this study,the experimental measurements of airflow and gas distributions were conducted in a 10 m full-scaled utility tunnel mockup,and gas diffusion characteristic was also investigated.Numerical simulation of utility tunnel leakage was also conducted by computational fluid dynamics(CFD).Different turbulence models and different air supply diffuser models were compared via the experimental results based on visualization and the relative root-mean-square error(RRMSE)index,which quan-titated the difference between the numerical and experimental results.The results showed that the standard k−εturbulence model and random air opening model could provide better results than other models.According to the experimental data analysis,it was necessary to consider the optimization of monitoring detector arrangements in actual utility tunnels.This study provided basic experimental data and the validated numerical model for the leakage source identification and underground tunnels simulation research.
