The Use of An Organic Self-Assembled Monolayer Coating to Promote Dropwise Condensation of Steam on Horizontal Tubes  

Oleh:

Andeen, G. B. ; Kilty, H. P. ; Das, A. K. ; Marto, P. J. ; Kumar, A.

Jenis: Article from Bulletin/Magazine
Dalam koleksi: Journal of Heat Transfer vol. 122 no. 2 (May 2000), page 278-286.
Topik: condensation; organic; self - assembled; monolayer coating; dropwise condensation; horizontal tubes

Ketersediaan

Perpustakaan Pusat (Semanggi) Nomor Panggil: JJ90.1 Non-tandon: 1 (dapat dipinjam: 0) Tandon: tidak ada

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Isi artikel

Hydrophobic coatings have been created through self - assembled monolayers (SAMs) on gold, copper, and copper - nickel alloy surfaces that enhance steam condensation through dropwise condensation. The monolayer is formed by chemisorption of alkylthiols on these metal surfaces. Due to their negligible thickness (10 – 15 Å), SAMs have negligible heat transfer resistance, and involve a minuscule amount of the organic material to pose any contamination problem to the system from erosion of the coating. The coating was applied directly to copper and 90 / 10 copper - nickel tubes, and to previously gold - sputtered aluminum tubes. The quality of the drops on SAMs, based on visual observation, was found to be similar for the three surfaces, with the gold surface showing a slight superiority. When compared to complete filmwise condensation, the SAM coating increased the condensation heat transfer coefficient by factors of 4 for gold - coated aluminum, and by about 5 for copper and copper - nickel tubes, under vacuum operation (10 kPa). The respective enhancements under atmospheric conditions were about 9 and 14. Comparatively, the heat transfer coefficient obtained with a bare gold surface (with no organic coating) was 2.5 times that of the filmwise condensation heat transfer coefficient under vacuum, and 3.4 at atmospheric conditions.

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