Transport Of Heat And Pollutants Across Different Floors In High-rise Naturally Ventilated Buildings

Due to the intensive infrastructure construction and rapidly expanding economic developments, the urbanization experiences rapid development. The urban atmospheric environment is destroyed because of the high density population, buildings, industries and traffic, which leads to serious environment problems. The problems of the extreme hot, air pollution and airborne disease transmission have posed a threat for people’s life productivity and health, especially for the outbreak of SARS in2003, bird flu in2006and the H1N1. These diseases had led to a great infectious risk for people’s health and aroused a public panic for the airborne virus. High-density high-rise buildings are considered as a main sign for urban developments, around which the atmospheric environment is very complex due to the heat, wind and building structures. The environmental problems arise for these kinds of buildings. The cross-contamination is one of the important problems in high-rise buildings during the outbreak of the airborne diseases. Therefore, reliable of prediction of temperature and pollutant distribution near a building is of vital importance in providing a comfortable and healthy environment and also improving the ventilation design and disease control.The present study numerically investigates transport of heat and pollutants among different floors under the condition of buoyancy-driven natural ventilation. First, two simplified building models with different strategies of openings are established. Second, the airflow, temperature distribution and concentration distribution are obtained. Third, the effect of different strategies of window openings, the intensity of heat source and pollutant source and the physical parameters of air pollutants is analyzed. Finally, The transport characteristics of heat, gas pollutants and particles are obtained.The results are as follows:(1) the flow is interacted with each other among different floors, and the heat, gas pollutants and particles could be transported to upper floors from the lower floors.(2) the strategies of window openings have an effect on the transport characteristics. The interaction is stronger for buildings with openings on singled-sided wall than buildings with one opening, which implies that the upper floors are more infected. For the heat and pollutants, the transport characteristics are different:First, for the heat transport, the temperature increases with floor level. Second, for the gas pollutants transport, the transport rate is influenced by the intensity of heat source and pollutant source. Moreover, the stronger the pollutant source, the stronger the airflow, and thus the higher the pollutant concentration in upper floors, which indicates a higher risk of infection. Third, for the particle transport, the particle distribution is influenced by flow intensity, the particle density and diameter. For the fine particles, the weaker the intensity of the flow, the higher the infection in upper floors; while for the coarse particles, the stronger the intensity of the flow, the higher infection in upper floors.The study concluded that the airflow interaction between different floors due to buoyancy force has an important effect on the vertical transport of heat and air pollutants in high-rise buildings, which is important for energy saving and disease control.