| With its convenient,safe,comfortable and energy-saving features,the city subway has become a widely used transportation system in our society.Most metro stations are underground buildings with significant sources of heat,humidity and pollution.Ventilation and air conditioning systems play a vital role in ensuring the comfort and health of the hot and humid environment,which is in the subway and the normal operation of the equipment of the station.In the current subway stations,the traditional mixed ventilation mode is adopted,and there are some problems such as low ventilation efficiency,poor thermal comfort and poor air quality.The research group proposed a new type of air supply mode—attached ventilation,which can use the evenly distributed structural cylinders in large-span buildings to attach and supply air.This paper mainly studies the engineering application of the attached ventilation in the public area of the two island platforms in Zhengzhou.Scientific and reasonable ventilation and air-conditioning airflow organization can ensure the comfort of the subway environment with less energy consumption.This paper is based on the single-column structure(Zhengzhou Aoxiang Road Station)and the double-column structure(Zhengzhou Jichangbei Station),comparing which of the two types of subway tower platforms with different building structures are more suitable,and using CFD to simulate the velocity field and temperature field of the public area of the subway platform.The vertical air temperature difference,air diffusion performance index(ADPI)and relative thermal index(RWI)were used to evaluate the air distribution in the active area under the two air supply modes(attached ventilation and mixed ventilation).The results show that in the public area of the subway island platform with two columns of single column and double columns,the velocity and temperature distribution of the personnel activity area under the attached ventilation mode are even,and the vertical air temperature difference meets the specifications.In terms of air distribution characteristics,the single-column attached ventilation and mixed ventilation were 84.38% and 61.88%,and the ADPI values of the double-column attached ventilation and mixed ventilation modes were 80.63% and 76.25%,respectively;The attached ventilation and mixed ventilation are 0.21 and 0.23 respectively,and the RWI values of the double-column attached air supply and mixed ventilation modes are 0.21 and 0.20 respectively.Under the premise of meeting the comfort requirements,the column attached air supply mode can simultaneously reduce the air supply volume and cooling capacity of the air conditioning system.The air volume of the single-column attached air supply system is reduced by about 38% compared with the mixed ventilation and air-conditioning system,and the cooling capacity is reduced by about 15%;the double-column attached air supply is reduced by about 36.8% compared with the mixed ventilation and air-conditioning system,and the cooling capacity is reduced by about 15%.It has been found that the attached ventilation can provide a comfortable environment for activities,and is an efficient and energy-saving air ventilation organization method.At the same time,in order to explore the influence of the change of the diffuser’s form on the attached ventilation mode,a rectangular diffuser,a circular diffuser and a semi-circular diffuser vertical wall attached model calculation model were established.Through the numerical simulation,combined with the existing velocity attenuation and temperature distribution formula of the linear slot diffuser,the velocity law of the jet axis in the air supply mode and the room temperature under the non-isothermal air supply are explored under the rectangular air outlet,the circular air outlet and the semi-circular air outlet.The effects of changing air supply speed,supply air temperature and indoor heat source conditions on the tissue movement of air supply with different air outlets were compared and analyzed. |
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