Infectious diseases(e.g.,coronavirus disease 2019)dramatically impact human life,economy and social development.Exploring the low-cost and energy-saving approaches is essential in removing infectious virus particles f...Infectious diseases(e.g.,coronavirus disease 2019)dramatically impact human life,economy and social development.Exploring the low-cost and energy-saving approaches is essential in removing infectious virus particles from indoors,such as in classrooms.The application of air purification devices,such as negative ion generators(ionizers),gains popularity because of the favorable removal capacity for particles and the low operation cost.However,small and portable ionizers have potential disadvantages in the removal efficiency owing to the limited horizontal diffusion of negative ions.This study aims to investigate the layout strategy(number and location)of ionizers based on the energy-efficient natural ventilation in the classroom to improve removal efficiency(negative ions to particles)and decrease infection risk.Three infected students were considered in the classroom.The simulations of negative ion and particle concentrations were performed and validated by the experiment.Results showed that as the number of ionizers was 4 and 5,the removal performance was largely improved by combining ionizer with natural ventilation.Compared with the scenario without an ionizer,the scenario with 5 ionizers largely increased the average removal efficiency from around 20%to 85%and decreased the average infection risk by 23%.The setup with 5 ionizers placed upstream of the classroom was determined as the optimal layout strategy,particularly when the location and number of the infected students were unknown.This work can provide a guideline for applying ionizers to public buildings when natural ventilation is used.展开更多
The widely utilized high efficient particulate air filters(HEPA)and electrostatic precipitator(ESP)respectively has the shortcomings of relatively high energy consumption and low filtration efficiency.In order to over...The widely utilized high efficient particulate air filters(HEPA)and electrostatic precipitator(ESP)respectively has the shortcomings of relatively high energy consumption and low filtration efficiency.In order to overcome the disadvantages of two traditional air filtration system,electrostatic assisted air filtration system(combining HEPA and ESP)has been proven to achieve high filtration efficiency and low energy consumption simultaneously.Predicting of V-I characteristics of electrostatic filtration system with configuration of“pin to filter medium to grounded device”is very essential and challenging due to the back corona phenomenon.This study utilized the back-corona based current model to predict the V-I characteristics of electrostatic system with different filter medium types and“pin-to-filter”distances.Experiments are conducted to provide data for model validation by changing filter types and locations of discharge pin.The results indicated that both of the predicted values of total discharge current and back-corona induced current agreed well with the experimentally measured data.This validated mathematical model could be used for preliminary design of electrostatic assisted filtration system with configuration of“pin to filter to grounded device”.Based on the V-I characteristics predicted by the semi-empirical model,the electrostatic filtration efficiency could be estimated.展开更多
基金supports from the National Natural Science Funds for Distinguished Young Scholar(No.52225005)the National Natural Science Foundation of China(No.52178069)+2 种基金the Fundamental Research Funds for the Central Universities(No.4301002171)Concordia University-Canada,through the Concordia Research Chair-Energy&Environment,and the support received through the Engineering and Physical Sciences Research Council(EPSRC)–funded CO-TRACE(COvid-19 Transmission Risk Assessment Case studiesEducation Establishments,EP/W001411/1)the COVAIR(Is SARS-CoV-2 airborne and does it interact with particle pollutants?,EP/V052462/1)projects,and“Knowledge Transfer and Practical application of research on Indoor Air Quality(KTP-IAQ)”project that is funded by the University of Surrey’s Research England funding under the Global Challenge Research Fund(GCRF).
文摘Infectious diseases(e.g.,coronavirus disease 2019)dramatically impact human life,economy and social development.Exploring the low-cost and energy-saving approaches is essential in removing infectious virus particles from indoors,such as in classrooms.The application of air purification devices,such as negative ion generators(ionizers),gains popularity because of the favorable removal capacity for particles and the low operation cost.However,small and portable ionizers have potential disadvantages in the removal efficiency owing to the limited horizontal diffusion of negative ions.This study aims to investigate the layout strategy(number and location)of ionizers based on the energy-efficient natural ventilation in the classroom to improve removal efficiency(negative ions to particles)and decrease infection risk.Three infected students were considered in the classroom.The simulations of negative ion and particle concentrations were performed and validated by the experiment.Results showed that as the number of ionizers was 4 and 5,the removal performance was largely improved by combining ionizer with natural ventilation.Compared with the scenario without an ionizer,the scenario with 5 ionizers largely increased the average removal efficiency from around 20%to 85%and decreased the average infection risk by 23%.The setup with 5 ionizers placed upstream of the classroom was determined as the optimal layout strategy,particularly when the location and number of the infected students were unknown.This work can provide a guideline for applying ionizers to public buildings when natural ventilation is used.
基金The authors would like to acknowledge the coordinated support from Natural Science Foundation of China(Grant No.51808138,51778385,51878442).
文摘The widely utilized high efficient particulate air filters(HEPA)and electrostatic precipitator(ESP)respectively has the shortcomings of relatively high energy consumption and low filtration efficiency.In order to overcome the disadvantages of two traditional air filtration system,electrostatic assisted air filtration system(combining HEPA and ESP)has been proven to achieve high filtration efficiency and low energy consumption simultaneously.Predicting of V-I characteristics of electrostatic filtration system with configuration of“pin to filter medium to grounded device”is very essential and challenging due to the back corona phenomenon.This study utilized the back-corona based current model to predict the V-I characteristics of electrostatic system with different filter medium types and“pin-to-filter”distances.Experiments are conducted to provide data for model validation by changing filter types and locations of discharge pin.The results indicated that both of the predicted values of total discharge current and back-corona induced current agreed well with the experimentally measured data.This validated mathematical model could be used for preliminary design of electrostatic assisted filtration system with configuration of“pin to filter to grounded device”.Based on the V-I characteristics predicted by the semi-empirical model,the electrostatic filtration efficiency could be estimated.
