Detail Heterogeneous Nucleation With Artificial Cavities   Oleh:  Klausner, James F. ; Yusen, Qi Jenis: Article from Bulletin/Magazine Dalam koleksi: Journal of Heat Transfer vol. 127 no. 11 (Nov. 2005), page 1189-1196. Topik: resonant cavities; heterogeneous nucleation; artificial cavities Ketersediaan Perpustakaan Pusat (Semanggi) Nomor Panggil: JJ90.10 Non-tandon: 1 (dapat dipinjam: 0) Tandon: tidak ada     Lihat Detail Induk Isi artikel Bubble incipience in artificial cavities manufactured from silicon has been studied using gas nucleation and pool boiling. Moderately wetting water and highly wetting ethanol have both been used as the bulk fluid with cylindrical cavities, as well as those with a triangle, square, and rectangle shape cross section. Nominal cavity sizes range from 8 to 60 µm. The incipience conditions observed for water using both gas nucleation and pool boiling suggest that bubble initiation originates from a concave meniscus. Cornwell's contact angle hysteresis theory for vapor - trapping cavities is used to explain the gas nucleation results. The pool boiling results are more difficult to explain. Using ethanol, cavities appeared to be completely flooded and were not activated using either gas nucleation or pool boiling. Using water and gas nucleation, cavities were almost always activated, provided the incipience criterion was satisfied ; in contrast cavities in pool boiling with water activated with different superheats during different experiments. The difference in incipience behavioUr between gas nucleation and pool boiling with water is explained based on vapor - trapping and thermal suppression considerations. Based on limited experimental results, it appears that the backpressure does not influence gas bubble incipience, provided the pressure difference is the same. The experimental results presented affirm the theory of heterogeneous nucleation from vapor-trapping cavities provided contact angle hysteresis and vapor trapping are fully accounted for. However, the results also suggest that the theoretical considerations required for a deterministic model for incipience from vapor - trapping cavities during boiling is more complex than previously hypothesized. Opini Anda Klik untuk menuliskan opini Anda tentang koleksi ini! Kembali

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