Study On Characteristic Impact Of Mechanical Ventilation Models On Pollutants Control In Large Space

Recently,with the application of building materials with harmful substances and poor ventilation,pollutant concentration in building increases which have greatly caused deterioration in air quality.Because of its distinctive characteristics such as frequently personnel flowing and complex pollution species,the problem of pollution is particularly outstanding in large space building.Therefore,the study on pollution distribution in large building space with different air supply modes at different positions is of great guiding significances.Firstly,based on the classification of large space buildings,the characteristics and way of air supply is summarized comprehensively,and two kinds of mechanical ventilation including displacement ventilation and push-pull ventilation are illustrated and compared in this paper.Secondly,formaldehyde(HCHO) is selected as the main pollutants in this paper. Introduction and summarization on predictive methods of pollution as well as its emission are detailed.Finally,in terms of simulation with CFD on large space model,the influences of velocity,temperature and position on pollutants concentration under the two kinds of ventilation are analyzed.Besides,the distribution of pollutant concentration and flow field under different conditions are also introduced.The ventilation efficiency respectively with displacement ventilation and push-pull ventilation is also compared.Through analysis of pollutant control on 12 kinds of conditions for mechanical ventilation,three methods are adopted to evaluate pollutant concentration on the condition that the rate of air supply and pollutant dispersion are the same:(1)pollutant concentration at working area and its upper part in displacement ventilation system is higher than that of push-pull ventilation system;(2)whether at section X,Y or Z,the pollutant concentration of displacement ventilation system is higher than that of push-pull system;(3) dimensionless concentration at some sections are very low in push-pull ventilation except for sections that close to pollution source.While for displacement ventilation,the dimensionless concentration increases ceaselessly with height rising.