Effect of Different Types of Structural Configuration on Air Distribution in a Compact Purification Device

In some old industrial plants,in order to meet the increasingly strict requirements of pollutant emission limits,it is necessary to install the compact filtration and/or purification devices in a given narrow machine room.Different types of structural configuration might influence air distribution inside these devices.The unreasonable air distribution might lead each part of filtration or purification media to operating at largely different air flow rates.Based on a computational fluid dynamics(CFD)model,this study explores the influence of different outlet positions and different upper heights on the flow field inside chamber.The porous medium model is employed to simulate the air flow in porous media.The changing structural configurations include three positioning cases of the outlet opening and eight height cases of the upper chamber.The root mean square is defined as the non-uniformity coefficient to evaluate the uniformity of air flow distribution.The results show that the farther distance between inlet and outlet openings will bring more uniform air distribution,and the increasing height of upper chamber totally trends to exhibit more uniform air distribution.

Uniformity and energy evaluation of equal cross-section ventilation system(ECVS)for long tunnel in underground buildings

Uniform ventilation is important for the safety of long tunnel in underground buildings,it is difficult to install the large size air duct to ensure the centerline of each cross-section of the traditional variable cross-section ventila-tion system(VCVS)superimposed on the same horizontal axis,which is significant to the ventilation uniformity,energy consumption and installation convenience of the VCVS.On the contrary,each cross-section of the Equal Cross-section Ventilation System(ECVS)has the same horizontal axis,therefore,it is more convenient to manu-facture and install the large size air duct in the underground long tunnel and achieve uniform ventilation.This study proposes an ECVS,using computational fluid dynamics(CFD)numerical simulation analyzed the influences of main duct velocity,aspect ratio,and outlet numbers on uniformity and energy consumption per unit air vol-ume(ECPV).It revealed that when each ventilation equalizer’s valve Angle𝛽is given,uniformity of air supply decreases slightly with an increase in the inlet velocity.When the air supply main duct aspect ratio increases,the outlet velocity standard deviation range is from 0.22 to 0.34.When outlet numbers N=7~12 and𝛽are constant,air supply uniformity and resistance coefficient𝜉also decrease with the decrease of outlet numbers.The outlet number has a significant influence on the uniformity of system air supply,main duct velocity,and aspect ratio are relatively small.ECPV is positively correlated with the main duct velocity and outlet number,and is negatively correlated with aspect ratio.