Study On The Heat And Mass Transfer Cooling Process Of Artificial Snow Droplets

The successful hosting of the 2022 Winter Olympics in Beijing has aroused people’s enthusiasm for participating in ice and snow sports and boosted the demand for the country’s ice and snow equipment industry.In order to promote the development of outdoor artificial snow making equipment technology,realize more energy-saving and efficient artificial snow making process,expand snow making area,and extend the time of outdoor snow and ice sports,it is necessary to accurately control the critical conditions of artificial snow making.The cooling process of micro droplets is the core process of artificial snow making by outdoor snow maker.This paper studies the heat and mass transfer and cooling process of small and micro droplets in this process.The main research work and conclusions are as follows:1.Based on the traditional theoretical model,the mathematical model of droplet heat and mass transfer process is innovatively improved.The relationship between droplet diameter and radiation absorption rate,the influence of solar radiation and space radiation on droplet cooling process were mainly considered,and the heat and mass transfer mechanism between single droplet and environment and its effect on droplet cooling process were described in detail.This work provides model support for simulating the artificial snow making process of outdoor snow machine.2.Experimental study on droplet evaporative cooling process.An experimental platform was built to verify the rationality of the mathematical model and to study the influence of the initial water temperature on the droplet cooling process.The experimental conclusions were consistent with the numerical results.3.Numerical study of droplet heat and mass transfer cooling process.Based on the improved mathematical model of droplet heat and mass transfer process,the influences of solar radiation,droplet initial diameter,ambient temperature,initial water temperature,ambient humidity,wind speed,artificial snowmaking working time and other factors on droplet cooling and evaporation process were numerically studied.The actual climatic conditions on October 18,2022 in Chongli District,Zhangjiakou City,The influence of solar radiation on droplet cooling and evaporation was calculated and analyzed,and the degree of influence was quantified.This work provides an important theoretical support for determining the critical droplet diameter of artificial snow making environment and snow making machine after water mist.The study found:(1)Under fixed conditions,the smaller the initial diameter of the droplet,the larger the surface area,the larger the volume loss rate,the higher the cooling rate,and the shorter the time to reach the crystallization temperature;(2)For droplets with the same particle size,the lower the initial water temperature,the smaller the driving force of temperature transfer,the smaller the drop cooling rate,the smaller the volume loss rate,but the shorter the time for droplets to reach the crystallization temperature;(3).The influence of solar radiation on the heat and mass transfer and cooling process of droplet increases with the decrease of particle size;(4)If the actual period of artificial snow making is put after sunset and before sunrise,the critical temperature of snow formation can be increased by about 1℃,which can effectively expand the duration of snow activities.