Experimental Study On Restraint Of Frost Fromation And Simulation And Forecast Of The Process

Frost formation is a common problem often encountered in the refrigeration and cryogenics industry. Without effective control, frost deposition may result in serious malfunction of cryogenic equipment and systems. There are many defrosting methods, but all these methods are energy-consuming and accompanied by a reduction in over all efficiency. On the basis of microscopic research, hydrophobic and hydrophilic coats were used to preventing frost formation on cold plate. Also, a simulation and forecast model were set up on the base of experimental data and theoretical analysis.A series of experiments of the coagulation and solidification process of the liquid droplet was taken out. Results show that the velocity of the collection of the liquid droplet increases with the decrease of the cold plate temperature and the increase of air humidity and temperature. By increasing the contact angle of the surfaces, one is able to speed the velocity of the collection and prolong the initial time of the solidification. Also, the equation of the solidification time has been obtained by regressing the experimental data as,By computing the row and column occupancy rate of ice crystal, it is found that the hydrophobic and hydrophilic surfaces have effect not only on the mass and height of the frost, but also on the distributing of ice crystal. The initial structure affects the whole process of the frost formation. Empirical correlations for the thickness of the frost formation on different surfaces were proposed as the functions of test time,contact angle,and so on. The equation is as follows,Based on one-dimension random growth model and the experimental data, the probability of the frost nuclei in this model was obtained.By controlling the parameter of the probability, a model of simulation of the frost formation by computer was set up. Thus, the frost formation on different surfaces,cold plate temperature,air humidity and temperature can be simulated by this model.Meanwhile, a forecast model which can forecast the frost distributing on next time was set up by changing the simulation model. The results agree well with the bulk of experimental data.