scispace - formally typeset
Search or ask a question
Author

Chun Chen

Bio: Chun Chen is an academic researcher from The Chinese University of Hong Kong. The author has contributed to research in topics: Airflow & Pressure drop. The author has an hindex of 26, co-authored 72 publications receiving 2419 citations. Previous affiliations of Chun Chen include Tsinghua University & Purdue University.


Papers
More filters
Journal ArticleDOI
Chun Chen1, Bin Zhao1
TL;DR: In this article, the authors provide an up-to-date revision for both experiment and modeling on relationship between indoor and outdoor particles, using three different parameters: indoor/outdoor (I/O) ratio, infiltration factor and penetration factor.

755 citations

Journal ArticleDOI
Chun Chen1, Bin Zhao1
TL;DR: Results from detailed numerical studies reveal how the evaporation of droplets, ventilation rate, airflow pattern, initial exhaled velocity, and particle component decide the droplet dispersion indoor.
Abstract: This study employs a numerical model to investigate the dispersion characteristics of human exhaled droplets in ventilation rooms. The numerical model is validated by two different experiments prior to the application for the studied cases. Some typical questions on studying dispersion of human exhaled droplets indoors are reviewed and numerical study using the normalized evaporation time and normalized gravitational sedimentation time was performed to obtain the answers. It was found that modeling the transient process from a droplet to a droplet nucleus due to evaporation can be neglected when the normalized evaporation time is <0.051. When the normalized gravitational sedimentation time is <0.005, the influence of ventilation rate could be neglected. However, the influence of ventilation pattern and initial exhaled velocity on the exhaled droplets dispersion is dominant as the airflow decides the droplets dispersion significantly. Besides, the influence of temperature and relative humidity on the dispersion of droplets can be neglected for the droplet with initial diameter <200 microm; while droplet nuclei size plays an important role only for the droplets with initial diameter within the range of 10 microm-100 microm. Practical Implications Dispersion of human exhaled droplets indoor is a key issue when evaluating human exposure to infectious droplets. Results from detailed numerical studies in this study reveal how the evaporation of droplets, ventilation rate, airflow pattern, initial exhaled velocity, and particle component decide the droplet dispersion indoor. The detailed analysis of these main influencing factors on droplet dispersion in ventilation rooms may help to guide (1) the selection of numerical approach, e.g., if the transient process from a droplet to a droplet nucleus due to evaporation should be incorporated to study droplet dispersion, and (2) the selection of ventilation system to minimize the spread of pathogen-laden droplets in an indoor environment.

181 citations

Journal ArticleDOI
TL;DR: In this article, an immersion method was proposed for embedding the homogenous growth of MOFs into nanofibers with a superior capability of wind resistance without film failure, and the prepared MOF-filter showed effective PM25 and formaldehyde removal.
Abstract: Indoor air quality is essential to public health as people spend most of their time indoors Hence, effective indoor air filtering is under heavy demand to deal with this challenge Metal–organic frameworks (MOFs) have been demonstrated as suitable candidates for air pollution control because of their unique properties, such as large surface area and rich functionalities The integration of MOFs into an organic polymer matrix is considered to be an effective method to control air pollution; however, an efficient and low-cost method to fabricate such filters is still lacking Herein, an immersion method was proposed for embedding the homogenous growth of MOFs into nanofibers with a superior capability of wind resistance without film failure The prepared MOF-filter shows effective PM25 and formaldehyde removal The PM25 filtration efficiency increased from 745% to 872% after integrating ZIF-67 nanocrystals into the electrospun PAN nanofibers Moreover, the PM25 filtration efficiency remains at more than 99% during a long-term test over 30 days The ZIF-67@PAN filter also achieves a formaldehyde removal efficiency of 84% This work not only proposes a scalable and low-cost method for fabricating flexible MOF-nanofiber filters but also holds great promise for improving indoor air quality and reducing the associated health risks

154 citations

Journal ArticleDOI
TL;DR: Differences in ozone mortality coefficients among cities appear to partially reflect differences in total ozone exposure resulting from differences in the amount of outdoor ozone that is transported indoors.
Abstract: Background: City-to-city differences have been reported for the increase in short-term mortality associated with a given increase in ozone concentration (ozone mortality coefficient). Although ozone concentrations are monitored at central outdoor locations, a large fraction of total ozone exposure occurs indoors. Objectives: To clarify the influence of indoor exposure to ozone of outdoor origin on short-term mortality, we conducted an analysis to determine whether variation in ozone mortality coefficients among U.S. cities might be partly explained by differences in total ozone exposure (from both outdoor and indoor exposures) resulting from the same outdoor ozone concentration. Methods: We estimated average annual air change rates (the overall rate at which indoor air is replaced with outdoor air) and used these to estimate the change in total ozone exposure per unit change in outdoor ozone exposure (ozone exposure coefficient) for 18 cities that had been included in the National Morbidity and Mortality Air Pollution Study (NMMAPS). We then examined associations between both parameters and published ozone mortality coefficients. Results: For the 18 targeted NMMAPS cities, the association between ozone mortality coefficients and ozone exposure coefficients was strong (1-hr ozone metric: R2 = 0.58, p < 0.001; 8-hr ozone: R2 = 0.56, p < 0.001; 24-hr ozone: R2 = 0.48, p = 0.001). When extended to another 72 NMMAPS cities, the associations remained strong (R2 = 0.47–0.63; p < 0.001). Conclusions: Differences in ozone mortality coefficients among cities appear to partially reflect differences in total ozone exposure resulting from differences in the amount of outdoor ozone that is transported indoors.

124 citations

Journal ArticleDOI
TL;DR: Seasonal and regional Differences in PM10 mortality coefficients appear to partially reflect seasonal and regional differences in total PM10 exposure per unit change in outdoor exposure.
Abstract: Background:Seasonal and regional differences have been reported for the increase in short-term mortality associated with a given increase in the concentration of outdoor particulate matter with an aerodynamic diameter smaller than 10 μm (PM10 mortality coefficient). Some of this difference may be be

118 citations


Cited by
More filters
Book ChapterDOI
30 Dec 2011
TL;DR: This table lists the most common surnames in the United States used to be Anglicised as "United States", then changed to "United Kingdom" in the 1990s.
Abstract: OUTPU T 29 OUTPU T 30 OUTPU T 31 OUTPU T 32 OUTPU T 25 OUTPU T 26 OUTPU T 27 OUTPU T 28 OUTPU T 21 OUTPU T 22 OUTPU T 23 OUTPU T 24 OUTPU T 17 OUTPU T 18 OUTPU T 19 OUTPU T 20 OUTPU T 13 OUTPU T 14 OUTPU T 15 OUTPU T 16 OUTPU T 9 OUTPU T 10 OUTPU T 11 OUTPU T 12 OUTPU T 5 OUTPU T 6 OUTPU T 7 OUTPU T 8 OUTPU T 1 OUTPU T 2 OUTPU T 3 OUTPU T 4 29 30 31 32 25 26 27 28 21 22 23 24 17 18 19 20 13 14 15 16 9

1,662 citations

Journal ArticleDOI
TL;DR: This review summarizes the main findings from published papers on the characteristics and sources and processes of ozone and ozone precursors in the boundary layer of urban and rural areas of China, including concentration levels, seasonal variation, meteorology conducive to photochemistry and pollution transport, key production and loss processes, ozone dependence on nitrogen oxides and volatile organic compounds, and the effects of ozone on crops and human health.

952 citations

Journal ArticleDOI
Chun Chen1, Bin Zhao1
TL;DR: In this article, the authors provide an up-to-date revision for both experiment and modeling on relationship between indoor and outdoor particles, using three different parameters: indoor/outdoor (I/O) ratio, infiltration factor and penetration factor.

755 citations