Study On The Influence Of Residential Ventilation System On Indoor Air Quality

Enhanced with the development of green building,building sealing,the problem of the indoor air quality is more and more serious,the environment of the residential building is not optimistic,the bedroom room ventilation is closely related to human health and quality of sleep,reasonable ventilation to improve air quality to meet the requirements of the construction of health,but also can avoid unnecessary energy waste so as to meet the requirements of green building.However,the study of bedroom environment is still a neglected topic,so this paper takes residential buildings as the research object,and uses two research methods,experiment and simulation,to carry out the research on the ventilation system of residential buildings.In the air distribution laboratory,the indoor temperature,humidity and CO₂ concentration under different air supply conditions are measured by controlling the air supply temperature,fresh air volume,number and position of tuyere,so as to preliminarily analyze the influence of air supply parameters on indoor air quality.The results show that the number and location of the tuyere affect the variation of CO₂ concentration in the laboratory under the premise of the same fresh air volume.The natural ventilation of 4 houses in a residential district in Beijing was tested for 2 months,and the temperature,humidity and CO₂concentration of the bedroom rooms were monitored continuously.The data of 1104h were calculated,and 58.6%of the time did not meet the requirements of the national standard n=0.7 times/h for ventilation.The CFD simulation software was used to establish the laboratory model,and the correctness of the model was verified by comparing the experimental results with the simulation results.Firstly,the important influencing factors of four air supply modes,namely upper and lower supply modes,displacement ventilation and layer ventilation,and the distribution of airflow parameters when coupled with floor heating are simulated,and the influence law of coupling of air supply modes and different room parameters on CO₂ diffusion is studied.By analyzing the velocity field,DR,CO₂concentration field,air age and PMV-PPD index to evaluate the air distribution under different working conditions,the results show that the displacement ventilation is the best in the same number of ventilation,and the upfeed upper return is the worst.When coupled with floor heating,it is found that floor ventilation may not achieve the desired effect in residential buildings in winter.When the air supply speed is 0.7m/s and 0.5m/s,the air quality is better than that of 0.9m/s,so the greater the air supply speed is,the better;When the air supply angle is 45°,the airflow distribution is the best,followed by 30°.The increase of indoor relative humidity will inhibit the diffusion of pollutants;When the two pollutants are released at the same time,the release of formaldehyde will inhibit the outward diffusion of CO_2.Secondly,the air quality created by the two kinds of head air supply modes in the breathing microenvironment was studied.Through the analysis of three-dimensional velocity flow field,CO₂ exposure intensity and MAA,it was shown that the air distribution created by the head air supply mode 1-2 had a better effect than the common four kinds of ventilation modes,and had a higher energy utilization rate and energy saving effect.Finally,a typical two-room and two-hall apartment is selected as the research object to simulate the difference of air distribution formed by the installation of unidirectional and bidirectional central fresh air system.Through the analysis of three-dimensional velocity flow diagram and CO₂ concentration distribution,it can be seen that the two-way flow fresh air system can form a better indoor flow field,avoid the generation of draft air,and the indoor flow rate is within the standard range,which is conducive to improving the level of human thermal comfort.There is an obvious problem of insufficient ventilation in the housing construction in our country.Natural ventilation and mechanical ventilation both show their respective advantages.Rational use of natural ventilation,in-depth understanding of the rules of mechanical ventilation to create air distribution,better use of this means to improve residential ventilation,this study provides a reference for the selection of residential building ventilation system.