The Basic Theoretical Research On The Factors Of Influencing Factors Of Liquid Drop Freezing Process On Cold Surface

When the cold surface temperature is lower than the triple point temperature of water,supercooled water droplets in the air will freeze when they meet the surface with lower solid temperature,with the decrease of temperature and time increasing,frost layer will be formed gradually.Similar phenomena have been found in many fields,such as low-temperature refrigeration systems,freezing of atmospheric components,aviation and so on,causing a large amount of energy to be consumed gratuitously,and seriously affecting the service life of equipment.The freezing phenomenon has brought a lot of harm to our daily life.At the same time,freezing method plays an important role in formation of rime landscape and seawater desalination.It is very valuable to master the technology in the process of droplet freezing.In this paper,the experimental law of liquid droplet freezing on solid surface under different conditions is studied.Observe the freezing influence factors of a single droplet on a cold surface,and to establish the relevant model.This article is mainly carried out from the following aspects:1)According to the theory of internal molecular structure,phase change dynamics,heat transfer and other related theories,the transfer of mass and energy will occur during phase change between substances,and the simulation of temperature distribution around the freezing process.2)The DSA100 droplet surface analyzer was used to visually study the droplet freezing process of different floor temperature,relative humidity,droplet volume and other factors,and observe the change of droplet volume and contact angle during freezing.It has been found that with the decrease of bottom plate temperature and the increase of freezing time,the droplet volume will increase to a certain extent.The change of contact angle can be observed obviously during the phase transition,and the phase interface will continuously move upward.3)The images of superimposed phase transition process are compared.The changes of droplet temperature,phase transition time,solid volume fraction and supercooling degree were analyzed under different conditions.Under certain conditions,the results have been found.The freezing time of droplets decreases with the decrease of the bottom plate temperature.The transformation time increases with the increase of humidity and volume.The height of the ice phase in the droplet changes rapidly at the beginning of the phase transition.When the set temperature is relatively low,there is a critical degree of supercooling.4)Simulation study on freezing process of single droplet on solid cold surface by fluent.The cooling process of ambient temperature around the droplet was simulated.The changes of internal temperature distribution,solid volume fraction and phase transformation time in different conditions were analyzed.and compared with the experimental results.The results have been shown that the temperature inside the droplet is a curved with radians.The change rule of phase transition time is consistent with the experiment,with the maximum relative error being about 18%,which indicates that the simulation can well verify the experimental process.