Cold Plate Temperature Effect on Droplet and Frost Crystal Behaviors at the Early Condensation Frosting Stage Considering Plate Edge Effect

Long Zhang1

Mengjie Song1,Email

Tianzhuo Zhan2

Jun Shen1

Chaobin Dang3,Email

1Department of Energy and Power Engineering, School of Mechanical Engineering, Beijing Institute of Technology, Beijing 100081, China
2Graduate School of Interdisciplinary New Science, Toyo University, 2100 Kujirai, Kawagoe, Saitama 350-8585, Japan.

3Graduate School of Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui-shi, Fukui 910-8507, Japan.

Abstract

The condensation frosting phenomenon commonly exists in engineering applications, and the relevant studies on flat plates with fixed surface temperatures are the most concerned in related fields. The existing studies usually focus on droplet condensation and frozen characteristics in the center region of cold plates and cannot reveal those near the plate edge. Therefore, a systematic study from droplet condensation to frost layer growth stages in the edge region of a cold plate was conducted in this paper. The experimental results showed that the frozen stage period of the edge-affected zone was significantly smaller than that of the unaffected zone. The ratio of average freezing wave propagation velocity in the edge-affected zone to that in the unaffected zone at plate temperatures of -9.0, -14.0, and -19.0 oC were 7.70, 5.56, and 5.11, respectively. Besides, the area-average equivalent diameter and coverage area ratio of droplets decreased with a decrease in plate temperature at the end of their respective droplet frozen stages. This study may help to better understand temporal and spatial condensation frosting characteristics on a horizontal cold plate with right-angle edges, and guide the establishment of a staged and divisional frosting model on cold plates. 

Cold Plate Temperature Effect on Droplet and Frost Crystal Behaviors at the Early Condensation Frosting Stage Considering Plate Edge Effect