Air cleaner is one of the viable options for particle removal in the indoor environment. Therefore, it is vital to understand the performances of air cleaners under various working conditions. In this work, the models for airflow pattern and particle transport in a room with an air cleaner were developed by combining the Lagrangian discrete trajectory model with the Eulerian fluid method. The effects of the operating conditions of the air cleaner on the particle transport characteristics were numerically investigated, including the volumetric flow rate and positioning of the air cleaner as well as the ejection orientation of the outlet air. The results show that the volumetric flow rate of the air cleaner is a key parameter affecting the particle concentration in the indoor environment. At low volumetric flow rates, the location of the air cleaner plays a significant role in the air cleaner performance. There is little difference in the removal processes of airborne particles between the horizontal and upward ejections of the air cleaner, but they are both superior to that with the downward ejection.
Air cleaners are expected to improve the indoor air quality by removing the gaseous contaminants and fine particles. In our former work, the effects of the air cleaner on removing the uniformly distributed particles were numerically investigated. Based on those results, this work further explores the performances of the air cleaner in the reduction of two nonuniform particle distributions generated by smoking and coughing. The Lagrangian discrete trajectory model combined with the Eulerian fluid method is employed to simulate the airflow pattern and particle transport in a room. In general, the results show that the particle fates have been resulted from the interaction between the emitting source and the air cleaner. And the position of the air cleaner is a key parameter affecting the particle concentration, for which a shorter distance between the air cleaner and the human body corresponds to a lower concentration. Besides, the air velocity emitted from the human mouth and the orientation of the air cleaner can also influence the transport of particles.
As a major source of air pollution in urban areas, the motor vehicle exhaust has attracted more and more attention due to its growing amount and serious harm to human health. It is of benefit to the pollutant control to make clear the transportation characteristics of vehicle exhausts. In this paper, the transportation characteristics of vehicle exhaust pollutants are investigated by means of the on-site measurement based on a typical Beijing expressway-Badaling expressway (G6 state expressway). The concentrations of CO, NO x , SO 2 and particles near the expressway were obtained, by which the variations of the particle number and mass concentrations, as well as the gas pollutant volume concentrations in the vicinity of the roadways with the distance from the expressway were fitted. The results show that the gas pollutant concentrations and particle concentrations decrease almost exponentially with the distance from the expressway, which is helpful for the air pollutant database establishment and future pollution control in big cities. particular matter, gas pollutant, concentration distribution, transportation characteristics Citation:
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