Simulation Study Of Indoor Formaldehyde Diffusion Based On Field Synergy

With the increase of people's indoor activity time,the requirements for the comfort and air quality of the indoor environment are becoming higher and higher.And the indoor formaldehyde content is getting more and more attention.In the cold regions of the north,In winter,people often adopt windproof and thermal insulation methods such as closed doors and windows,which makes the indoor pollutant content continue to increase,endangering human health.In the north,residential houses currently use low-temperature floor heating in winter and central airconditioning mechanical ventilation in offices in summer.Therefore,for the different ventilation requirements in winter and summer.This topic mainly uses the computational fluid dynamics(CFD)method to simulate the indoor formaldehyde concentration during the natural ventilation of heating rooms in civil houses in winter and the distribution of formaldehyde concentration under the common ventilation methods in office air-conditioned rooms in summer.And apply the mass transfer field synergy theory to optimize the analysis of the mass transfer diffusion process of pollutants in the room.Then by changing the location of the pollution source and the way of ventilation,the synergy between the speed and the concentration gradient during the mass transfer process can be improved to reduce the concentration of pollutants.Provide reasonable ventilation suggestions to improve the ventilation effect and reduce the indoor formaldehyde content.Firstly,the sources,hazards and limit standards of indoor formaldehyde are introduced in detail.For the research content of this subject,by referring to relevant domestic and foreign literatures in this direction,the indoor pollutant release model is summarized to determine the formaldehyde release parameters.The simulation calculation is also determined.The control equations,turbulence models and component transport models in the simulation calculations were determined,and the application of the mass transfer field synergy theory to the formaldehyde mass transfer diffusion process was analyzed based on the heat transfer and mass transfer analogy.Secondly,a newly renovated residential house and an experimental office of a university which were in Jinan were selected as the research objects for indoor formaldehyde diffusion in winter and summer.The indoor formaldehyde diffusion process was simulated in winter and summer respectively by CFD simulation.In winter,the main simulation calculation of the transient diffusion process of formaldehyde under the conditions of closed and natural ventilation in civil residential rooms.Determine the optimal intermittent ventilation time by comparing and analyzing the concentration of formaldehyde in different closed time in each room.The transient simulation of natural ventilation is calculated based on the simulation results of closed working conditions.By comparing the distribution of formaldehyde concentration in each room when the windows of different rooms are opened,the optimal combination of window opening methods is determined.Summer simulation calculation of the steady-state diffusion process of indoor formaldehyde in the office room under floor air supply,displacement ventilation and mixed ventilation.And comparative analysis of the distribution of the air velocity field,temperature field and formaldehyde concentration field in the personnel work area under different ventilation methods.Finally,based on the analogy of heat transfer and mass transfer,we further applied the theory of mass transfer field synergy to analyze the mass transfer and diffusion process of the location of the pollution source and the ventilation method for formaldehyde being diluted indoors.Influence of concentration field and the synergistic effect of fluid velocity and concentration gradient.The smaller the angle between the direction of the indoor gas velocity and the concentration gradient,the better the synergy between the velocity field and the concentration field,the better the mass transfer effect,and the more beneficial it is for the introduction of fresh air to the indoor formaldehyde dilution and enhanced purification efficiency.The simulation results provide a theoretical basis for measures to improve indoor air quality,and have certain guiding significance for the design of natural ventilation strategies for civil residences and the design of air-conditioning ventilation methods for office buildings.