Research On The Influence Of Evaporative Cooling Air Conditioning System On Fresh Air Particles And Indoor Environment

People’s stay indoors takes up a relatively large amount of time in their lives,and indoor air quality significantly affects people’s physical and mental health and work efficiency.Reasonable ventilation can replace the old indoor air with fresh air to ensure the freshness of indoor air.Direct evaporative cooling technology cools the air through the evaporation of water.When the water evaporates,it absorbs heat from the surrounding air,so the air is cooled,and the cooled air can be used as indoor air supply.Direct evaporative cooling air conditioners can not only adjust indoor temperature and humidity,but also remove aerosol particles in the air,which is more economical and energy-saving than traditional artificial refrigeration and dehumidification air conditioners.The concentration of fresh air particles directly affects the indoor air quality.The fresh air can reduce the particle concentration through the watersprinkling filling section,which in turn can dilute the indoor particle concentration to a lower level.Stratum ventilation has the characteristics of short air supply path and high ventilation energy efficiency.The combination of evaporative cooling and stratum ventilation ensures that the indoor comfort is satisfied at a higher air supply temperature.This paper is based on the Workbench 2020R1 platform for modeling,meshing,and parallel computing with user-defined functions.Based on the porous media model,a twodimensional numerical model of the direct evaporative cooling filler was established to simulate the removal efficiency of particles in the fresh air by the spray filler under different water drenching density,head-on wind speed and particle size.Based on the RNG k-e model to simulate the turbulent flow field,and the Lagrangian discrete phase model to simulate the motion field of particles,a three-dimensional numerical model of the classroom was established.For classroom with high personnel density,consider the carbon dioxide concentration during the breathing process of the personnel,analyze the indoor carbon dioxide concentration distribution,particle concentration distribution,thermal comfort,and mean age of air under different exhaust positions,and analyze the migration path of particles along with the airflow to determine the best location of the exhaust outlet.The Rosin-Rammler distribution is used to determine the particle size distribution in the atmosphere of Taiyuan City,Shanxi Province.Numerical calculations were carried out on the efficiency of spraying fillers to remove aerosol particles in the atmosphere with a particle size range of 1-10μm.The results show that when the head-on wind speed and water drenching density are constant,as the particle size increases,the particle penetration rate decreases successively.When particle size and the headon wind speed are constant,the penetration rate of the particles decreases with the increase of the water drenching density.When the particle size and water drenching density are constant,the penetration rate of the particles increases with the increase of the head-on wind speed.The simulation of the indoor environment of classrooms arranged at different positions of the exhaust outlets shows that the position of the exhaust outlets reflects the difference in indoor air distribution and affects the indoor air quality.The location of the exhaust outlets at the top and middle area of the work area has the best effect.The indoor thermal environment that changes from time to time can meet thermal comfort,and the carbon dioxide concentration and particle concentration in the breathing zone meet the specification requirements.