2021 Volume 38 Issue 2 Pages 59-
Frost formation on cryogenic heat exchangers is a serious problem. In this study, the effects of the surface temperature of the flat plate and mainstream humidity on the frost mass, thickness and density were experimentally investigated under forced convection. The surface temperature was set to -10, -20, -30 °C, and the absolute humidity of the mainstream was set to 8, 12, 16 g⋅m-3. The experiment time was set to within 600 seconds to investigate the initial stage of frost formation. In addition, a one-dimensional frost layer growth model was constructed and compared with the experimental values. As the result, the increasing rate of frost mass is constant over time and is proportional to the difference between the mainstream absolute humidity of the mainstream and the amount of saturated water vapor on the cooling surface. The frost thickness increases rapidly immediately after the start of frost formation, and then the increase rate decreased rapidly. Distribution of the frost shape in the flow direction was also measured. At the front end, the frost layer grows rapidly at the beginning of frost formation. On the other hand, the frost layer at the rear end grows gradually over time.