Experimental study of water drop freezing process on cryogenic cold surface

To investigate the impacts of cold surface temperature and wet air state on the freezing process and phenomena of a single water drop, quantitative measurements were carried out at various cold plate surface temperatures ranging from -165 degrees C to -30 degrees C. The covered cold surface temperature range were further divided into ordinary-low temperature group (-70 degrees C - -30 degrees C) and cryogenic temperature group (-165 degrees C - -100 degrees C). It was found that the cold surface temperature has an obviously effect on the drop freezing completion time, and it decreases with the decrease of the cold plate surface temperature. In comparison to the diameter change ratio and area change ratio, the height change ratio of a drop before and after freezing is more affected by cold surface temperature. The freezing front grows upward along the cold surface, gradually changes from convex to concave and the appearance of tip singularity indicates the completion of freezing. The internal temperature change of water drops is greatly influenced by air temperature and cold plate surface temperature, though it will finally tend to be stable. These findings can enrich understanding and analyzing water drop freezing phenomena under different cold surface temperature conditions, especially under cryogenic conditions.