Experimental Study On Performance Characteristics Of Residential Ventilation Window And Optimization Of Ventilation Strategy In Heating And Air Conditioning Period

Domestic buildings have increasingly high requirements for air tightness,and a new policy issued by the Ministry of Housing and Urban-Rural Development requires energy efficiency standards in key parts of buildings,such as doors and Windows,to meet advanced international standards by 2020.The better the air tightness,the air change rates of the building are controlled,but the problems caused at the same time can not be ignored.In the air-conditioning cooling season and heating season,the indoor CO₂concentration greatly exceed the standard.If effective ventilation cannot be carried out,it will affect the health of people.Excessive ventilation will increase the energy consumption of HVAC system.This paper mainly studies the improvement of indoor air quality under the condition that the highly air tightness of energy-saving buildings makes the doors and windows closed during the heating and air conditioning period.Firstly,this paper summarizes the air tightness of typical buildings in Tangshan,Tianjin,Urumqi,Hebi and other cities and the main application methods of building air tightness detection in China through literature research.But the results of the study on airtightness is about the construction of the 1980 s,the current energy saving building air tightness has greatly increased,therefore,combining the tightness of the typical cities in Yangtze river basin research conclusion household investigation about the present situation of residential indoor CO₂ concentration,10 rooms of 8 families are selected to monitor.It is found that the CO₂ concentration in the room during the building heating and air conditioning period is at a very unideal height most of the time at night,so the necessity of natural ventilation to make up for the indoor fresh air is introduced,and the ventilation principle of natural ventilation only under hot pressure,only under wind pressure and under the combined action of hot pressure and wind pressure is introduced.And then build the different ventilation experiment platform,select the best structure of double duct ventilation and air ventilation window,through the tracer gas method testing air change rates under different outdoor wind speed level and different condition of room temperature difference between indoor and outdoor.The performance characteristics of ventilation Windows were studied by analyzing the air change rates,the improvement effect of indoor air quality and the dilution efficiency of indoor pollutants.By comparing two different types of ventilation Windows,it is found that in Chongqing,the ventilation potential of B-type ventilation Windows is greater than that of A-type ventilation Windows,and B-type ventilation Windows also show better performance in terms of the dilution and dissipation of pollutants.But the stability and energy saving,comfort performance of A type ventilation window is better than B type.Then,through ICEM modeling,air-conditioned rooms without ventilation Windows,air-conditioned rooms with type A ventilation Windows and air-conditioned rooms with type B ventilation Windows were established.Through Fluent numerical simulation,the velocity field and temperature field distribution in the airflow cavity formed between the layers of glass of different type ventilation Windows are studied.The parameters of the air inlet height section,the standing posture section of 1.7m,the sitting posture section of 1.1m and the permeable air outlet height section of the room were further analyzed.In addition,typical cities under five climate zones in China were selected,combined with outdoor meteorological conditions and building energy conservation design standards,the regional adaptability of ventilation Windows was further comprehensively studied,and the ventilation performance,the distribution of air distribution in the room,and the thermal comfort of people caused by the ventilation windows were analyzed.Finally,the outdoor meteorological parameters and the concentration of PM_2.5pollutants in Chongqing,a typical city in the Yangtze River Basin,were analyzed.Combined with the analysis of the dynamic mass balance equation of indoor and outdoor PM_2.5 concentration,and then,the dynamic equilibrium relationship between PM_2.5concentration,CO2 volume fraction and air volume was established through the ventilation window,which connected the indoor and outdoor environment.The optimal operation strategies of ventilation Windows under summer and winter conditions were obtained:in hot summer,the minimum fresh air volume exists,the limit of CO2 volume percentage(C_min)is the main control standard of ventilation window,and A PM_2.5 filter net is added inside the A type ventilation window to speed up the dilution of indoor PM_2.5concentration.The best operation strategy in winter is to take the indoor PM_2.5concentration limit N_maxas the main control index,obtain the maximum air volume of ventilation window(Q_windowmax),and use indoor air purifier to accelerate the removal of indoor PM_2.5.