Numerical simulation study on influence of NO2 emitted from household heating on indoor and outdoor air quality in Shanghai

Taking a six-storey residential building in Shanghai as an example, the diffusion characteristics of NO2emitted from household heating under the influence of outdoor wind speed, outdoor wind direction and emission level of wall-mounted gas boilers are studied by CFD numerical simulation method. The simulated results are compared with the concentration limit of NO2in the existing standard. The results show that natural ventilation can promote the transmission of NO2emitted by wall-mounted boilers from outdoor to indoor, which results in indoor NO2concentration exceeding the standard limit. The lower the emission level of wall-mounted boilers is, the more serious the problem of exceeding the standard limit caused by indoor and outdoor transmission is. The closer the wind direction is to the north, the higher the overall level of NO2concentration in the indoor and regional microenvironment is. The NO2concentration is highest on the top floor and lowest on the ground floor. The NO2concentration distribution in the regional microenvironment is significantly affected by the emission level of the wall-mounted boilers, the outdoor wind speed and the wind direction. The higher emission level and the higher wind speed are more conducive to the diffusion and dilution of pollutants in the environment.