Study On Thermal Environment And Air Flow Optimization Of An Underground Commercial Buildings In Zhengzhou

With the acceleration of modernization,the deterioration of the urban environment,the shortage of land resources,overpopulation,and other problems have emerged one after another.In this case,the development and utilization of underground space have become an inevitable choice for the social development of all countries in the world.Now,China has become one of the countries with the largest efforts in underground space development in many aspects,such as subway and underground complex.As an emerging consumer place,the indoor environment of underground commercial buildings is also getting more and more attention.As a first-tier city in central China,underground commercial buildings in Zhengzhou have been widely used.Creating a good indoor thermal environment is an effective measure to increase the attraction of underground commercial buildings.However,the research on the thermal environment of commercial buildings mainly focuses on the above ground buildings.The air quality,thermal environment and related optimization problems of underground commercial buildings are urgent to be studied.Based on this phenomenon,a representative multifunctional underground commercial building in Zhengzhou was selected to investigate and optimize the thermal environment in this paper.The research results are as follows:(1)The variation of thermal environment and air quality of different functional areas in the commercial building was studied through the field study in the summer and winter of 2020.The results show that the change of outdoor air temperature and humidity has a lag effect on the air temperature and humidity of the underground shopping mall,and indoor air temperature and humidity fluctuation range is smaller.In the aspect of indoor thermal environment,the air temperature in different functional areas is unevenly distributed,as the temperature in the catering area is highest during summer,which the average temperature was 29.1℃,whereas the sundry goods area is coldest in winter as the temperature is always below 16℃.In the aspect of indoor relative humidity,the humidity in underground shopping malls is too high,and the humidity in each zone is higher than 60%in summer.The measured results of the air quality show that,CO2 concentration in garment area and catering area rises sharply in their respective peak business hours,resulting in CO2 concentration exceeding the standard.In winter the phenomenon of excessive pollutant concentration is mainly caused by the high concentration of PM2.5 in catering area.From the perspective of thermal comfort,the thermal comfort of the underground shopping mall generally does not meet the requirements.(2)Based on the measured data,the indoor environment was evaluated by fuzzy matrix.The indoor environment quality was divided into three grades,relevant parameters were selected and membership functions were established in different grades,and a fuzzy evaluation matrix was obtained to evaluate the indoor environment grade.The results show that the environmental quality of each area is related to the function and the flow of people,and the order of environmental quality of each area is sundry goods area>garment area>catering area.(3)According to the measured and evaluated results,it is found that there are poor thermal environment and poor air quality in the catering and garment areas of underground commercial building,so Airpak software is used to simulate the thermal environment and air distribution of theese two areas.Through the comparative analysis of indoor air temperature,air velocity,and air distribution uniformity under different schemes,the results show that the air distribution mode of the side supply is more suitable for the catering area,and the air distribution mode of up and down is suitable for garment area.Based on the above research,the temporal and spatial distribution rules of thermal environment and air quality of multi-functional underground commercial buildings were obtained in this project,and the optimization suggestions of air distribution in different areas were put forward based on the function and layout of buildings.The conclusions can provide a theoretical basis for the construction of thermal environment and related energy-saving transformation of underground commercial buildings.