QQ客服 官方微博 反馈留言

	Visual and theoretical analyses of the early stage of frost formation on cold surfaces
	Xiaomin Wu ; Wantian Dai ; Xiaofeng Shan ; Weicheng Wang ; Liming Tang
	2010-10-12 ; 2010-10-12
关键词	Theoretical or Mathematical/ drops free energy heat transfer/ frost formation cold surfaces hydrophobic coated copper surfaces contact angles frozen droplets Gibbs free energy barrier/ A4725Q Convection and heat transfer A4755K Multiphase flows
中文摘要	Meso-scale visual observations were conducted to investigate the process of frost formation on both bare and hydrophobic coated copper surfaces, which had contact angles of 56 degrees and 110 degrees . The experiments were carried out for -20-0 degrees C surface temperatures, 19-22 degrees C ambient air temperatures, and 15-85% relative humidities. The tests showed that the frost formation on cold surfaces was not a simple process of transition from steam directly to frost, but actually followed five steps: the formation of condensate droplets, droplet growth including coalescence of the supercooled droplets, freezing of the droplets, formation of initial frost crystals on the frozen droplets, and growth of frost crystals accompanied by collapse of some of the crystals. Compared to the bare copper surface, the hydrophobic surface had a sparser distribution of condensate droplets but larger droplet sizes, delayed droplet freezing and frost formation, and a smaller frost height, all of which support the observation that the hydrophobic surface retards frost formation and growth. The frosting phenomenon was also analyzed theoretically. The initial vapor condensation before frosting was explained based on the free energies for nucleation. For condensation of steam on cold surfaces below O degrees C, the Gibbs free energy barrier for water nuclei is smaller than that for ice nuclei, so condensate droplets appear before frost on cold surfaces. Further, since the hydrophobic surface has a higher Gibbs free energy barrier for nucleation than the bare surface, the droplets form more readily on the bare surface.
语种	英语
出版者	Begell House Inc. ; USA
内容类型	期刊论文
源URL	[http://hdl.handle.net/123456789/79996]
专题	清华大学
推荐引用方式 GB/T 7714	Xiaomin Wu,Wantian Dai,Xiaofeng Shan,et al. Visual and theoretical analyses of the early stage of frost formation on cold surfaces[J],2010, 2010.
APA	Xiaomin Wu,Wantian Dai,Xiaofeng Shan,Weicheng Wang,&Liming Tang.(2010).Visual and theoretical analyses of the early stage of frost formation on cold surfaces..
MLA	Xiaomin Wu,et al."Visual and theoretical analyses of the early stage of frost formation on cold surfaces".(2010).

个性服务

查看访问统计

相关权益政策

暂无数据

收藏/分享

除非特别说明，本系统中所有内容都受版权保护，并保留所有权利。