An experimental study on edge-affected frosting characteristics on a vertical cold plate at different air velocities

Abstract

Frosting always plays negative roles in engineering fields. To accurately predict and control the frosting process on the vertical plate surface with the edge effect considered, an experimental study on the frosting characteristics with air velocities between 1.2 m/s and 2.2 m/s of a vertical cold plate is conducted. The results show that the droplet condensation and coalescence stage duration obviously decreases as the air velocity decreases, while the edge effect has not a significant influence on this duration. Besides, the edge effect and the rise of air velocity will facilitate an increase in the droplet growth. The droplet growth coefficients in edge-affected regions for Cases 1, 2, and 3 are around 1.02, 1.06, and 1.19, and those in unaffected regions are 0.96, 1.01, and 1.07, respectively. At the end of the droplet condensation and coalescence stage, the equivalent width of the edge-affected regions for Cases 1, 2, and 3 are 2.46 × 10−4 m, 1.77 × 10−4 m, and 1.91 × 10−4 m, respectively. The average frost layer thickness reaches 8.97 × 10−4 m for 1.2 m/s at 2,400 s, and it increases by 7.6 % and 12.6 % when the air velocity increases to 1.7 m/s and 2.2 m/s, respectively. The results of this study are expected to deepen the understanding of the frost formation process on a vertical cold plate, and guide the frost detection and defrosting technologies.