The acceleration of industrialization worsening indoor environments of industrial buildings has drawn more attention in recent years.Natural ventilation can improve indoor air quality(IAQ)and reduce carbon emissions.T...The acceleration of industrialization worsening indoor environments of industrial buildings has drawn more attention in recent years.Natural ventilation can improve indoor air quality(IAQ)and reduce carbon emissions.To evaluate gaseous pollutant levels in industrial buildings for the development of buoyancy-driven natural ventilation,two theoretical models of pollutant flushing(Model I and Model II)are developed based on the existing thermal stratification theory in combination with the mixing characteristics of lower pollutant.The results show that indoor pollutant flushing is mainly dependent on the pollution source intensity and effective ventilation area.The mixing characteristics of lower pollutant has an important effect on pollutant stratification and evolution during ventilation,but it does not change the prediction results at steady state.When the dimensionless pollution source intensity is larger than 1,the pollution source should be cleaned up or other ventilation methods should be used instead to improve IAQ.In addition,the comparisons between Model I and Model II on instantaneous pollutant concentration are significantly influenced by the pollution source intensity,and the actual pollutant concentration is more likely to be between the predicted values of Model I and Model II.To reduce pollutant concentration to a required level,the pollution source intensity should be in a certain range.The theoretical models as well as the necessary conditions for ventilation effectiveness obtained can be used for the ventilation optimization design of industrial buildings.展开更多
A novel functional magnetic polyimide loaded with cobalt ferrite nanoparticles by coprecipitation method was proposed,and XRD,FTIR,SEM technologies were employed to study their physicochemical properties.The filtra-ti...A novel functional magnetic polyimide loaded with cobalt ferrite nanoparticles by coprecipitation method was proposed,and XRD,FTIR,SEM technologies were employed to study their physicochemical properties.The filtra-tion performance of non-magnetic and magnetic polyimide were examined by experimental system.The effects of dust resistance,filtration velocity and initial dust concentration on the filtration performance of magnetic polyimide were investigated under different dust loadings.The results revealed that presence of𝜌-лconjuga-tion between the cobalt ferrite and polyimide fiber resulted in easily load on the fiber surface for cobalt ferrite nanoparticles.The magnetic polyimide exhibited good filtration efficiency especially in the range of particle size less than 2μm.The filtration efficiency of magnetic polyimide filter materials increased by nearly 20%com-pared with the primary polyimide.Due to the loading of cobalt ferrite,the resistance of the magnetic polyimide increased,while the resistance growth rate decreased from 100%to 29%with increased filtration velocity from 0.5 m/min to 2.5 m/min.展开更多
基金This work is supported by the National Key Research and Development Program(No.2018YFC0705305)the Fundamental Research Funds for the Central University of Donghua University(No.2232017A-09).
文摘The acceleration of industrialization worsening indoor environments of industrial buildings has drawn more attention in recent years.Natural ventilation can improve indoor air quality(IAQ)and reduce carbon emissions.To evaluate gaseous pollutant levels in industrial buildings for the development of buoyancy-driven natural ventilation,two theoretical models of pollutant flushing(Model I and Model II)are developed based on the existing thermal stratification theory in combination with the mixing characteristics of lower pollutant.The results show that indoor pollutant flushing is mainly dependent on the pollution source intensity and effective ventilation area.The mixing characteristics of lower pollutant has an important effect on pollutant stratification and evolution during ventilation,but it does not change the prediction results at steady state.When the dimensionless pollution source intensity is larger than 1,the pollution source should be cleaned up or other ventilation methods should be used instead to improve IAQ.In addition,the comparisons between Model I and Model II on instantaneous pollutant concentration are significantly influenced by the pollution source intensity,and the actual pollutant concentration is more likely to be between the predicted values of Model I and Model II.To reduce pollutant concentration to a required level,the pollution source intensity should be in a certain range.The theoretical models as well as the necessary conditions for ventilation effectiveness obtained can be used for the ventilation optimization design of industrial buildings.
基金supported by the National Key Research and Develop-ment Program of China(2018YFC0705300)the Special Funds and Key Projects of Fundamental Scientific Research Business Fees in Central Universities(2232017A-09,CUSF-DH-d-2017097).
文摘A novel functional magnetic polyimide loaded with cobalt ferrite nanoparticles by coprecipitation method was proposed,and XRD,FTIR,SEM technologies were employed to study their physicochemical properties.The filtra-tion performance of non-magnetic and magnetic polyimide were examined by experimental system.The effects of dust resistance,filtration velocity and initial dust concentration on the filtration performance of magnetic polyimide were investigated under different dust loadings.The results revealed that presence of𝜌-лconjuga-tion between the cobalt ferrite and polyimide fiber resulted in easily load on the fiber surface for cobalt ferrite nanoparticles.The magnetic polyimide exhibited good filtration efficiency especially in the range of particle size less than 2μm.The filtration efficiency of magnetic polyimide filter materials increased by nearly 20%com-pared with the primary polyimide.Due to the loading of cobalt ferrite,the resistance of the magnetic polyimide increased,while the resistance growth rate decreased from 100%to 29%with increased filtration velocity from 0.5 m/min to 2.5 m/min.
