Simulation And Analysis Of Indoor Formaldehyde Distribution In Harbin Winter

In the cold area of Northeast China,various measures are taken to keep airtight and warm in winter,resulting in the accumulation of indoor air pollutants and the continuous decline of air quality.Long-term living in the room with poor air quality will cause serious harm to the body.Natural ventilation can provide fresh air for indoor,dilute indoor odor and contaminate.In this paper,the computational fluid dynamics(CFD)method is used to explore the diffusion rule of indoor formaldehyde in closed and natural ventilation conditions,so to summarize the reasonable natural ventilation mode and improve the effect of natural ventilation in winter.First,the outdoor air pollution index(AQI)and air temperature of Harbin during the heating period from 2016 to 2017 were collected and counted.The AQI data and the reasons for its change are analyzed.The changing rule of air quality yearly,monthly and hourly is summarized.The outdoor air temperature data are analyzed,and the hourly temperature of outdoor air is obtained.Considering the above two factors,we get the best natural ventilation time and the corresponding air temperature variation in Harbin for each day,which provides a basis for determining the boundary condition of numerical simulation.Secondly,one new decorated residential apartment in a residential area in Harbin is the research object.The mathematical model of formaldehyde emission from the bedroom floor is defined by using the custom programming in C language.Based on the ANSYS Fluent platform,the laminar flow model is selected to simulate the three-dimensional diffusion process of formaldehyde released in the bedroom floor.The distribution of formaldehyde concentration in the horizontal and high direction was analyzed after closed 1h and 12 h,and the indoor formaldehyde diffusion law under the closed condition was obtained.Finally,a physical model with external computing domain is built with Solidwork,and ANSYS Icem is used to divide the structure grid.Based on the ANSYS Fluent platform,the k-e turbulence model is used to simulate the threedimensional flow of air and pollutants indoor and outdoor during natural ventilation.The outdoor pressure distribution and velocity distribution,indoor velocity distribution,temperature distribution and formaldehyde concentration distribution were analyzed.The influence of the residence type,the opening mode of the flat window and the setting of the air vent on the indoor natural ventilation effect is explored,and a reasonable natural ventilation method is obtained.The research results have certain guiding significance for improving the indoor air pollution control and the design of buildings by natural ventilation in winter.