Diffusion characteristic of air pollutant from district heating source driven by urban wind field and layout optimization

District heating is a major contributor to urban air pollution due to the massive emissions from fossil fuel combustion. This paper investigates the diffusion characteristics of air pollutants from district heating sources (DHS) driven by the urban wind field. Firstly, the urban air quality was simulated using the coupled Weather Research and Forecasting model - Community Multiscale Air Quality model (WRF-CMAQ) based on the actual heating emissions in the study region. the results were validated using observed meteorological and environmental data. Next, the study regions were divided into sub-regions based on the prevailing wind direction during the heating season. numerical experiments were designed by planning the heating emission into sub-regions as optimized layouts for DHS. Finally, the air quality was predicted for different layouts using WRF-CMAQ and assess the output of PM2.5 as the indicator. The findings reveal that moving the DHS close to the suburban areas can significantly improve overall air quality, and the best improvement can be obtained by arranging all DHS within the defined windward or leeward sub-regions. It is expected that these findings will provide guiding principles for planning DHS from the perspective of environmental management.