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Titolo:
The effective use of heat transfer additives for steam condensation
Autore:
Kim, KJ; Lefsaker, AM; Razani, A; Stone, A;
Indirizzi:
Univ Nevada, Dept Mech Engn, Reno, NV 89557 USA Univ Nevada Reno NV USA 89557 Nevada, Dept Mech Engn, Reno, NV 89557 USA
Titolo Testata:
APPLIED THERMAL ENGINEERING
fascicolo: 18, volume: 21, anno: 2001,
pagine: 1863 - 1874
SICI:
1359-4311(200112)21:18<1863:TEUOHT>2.0.ZU;2-J
Fonte:
ISI
Lingua:
ENG
Soggetto:
FALLING FILM ABSORPTION; DYNAMIC SURFACE-TENSION; WATER-VAPOR; 2-ETHYL-1-HEXANOL; AUGMENTATION; GAS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Engineering, Computing & Technology
Citazioni:
21
Recensione:
Indirizzi per estratti:
Indirizzo: Kim, KJ Univ Nevada, Dept Mech Engn, Reno, NV 89557 USA Univ Nevada Reno NV USA 89557 Dept Mech Engn, Reno, NV 89557 USA
Citazione:
K.J. Kim et al., "The effective use of heat transfer additives for steam condensation", APPL TH ENG, 21(18), 2001, pp. 1863-1874

Abstract

Reported herein are the results of the experimental investigations on the effect of small amounts of heat transfer additives (C-add < 1000 ppm) on steam condensation in a bundle of horizontal tubes that are internally cooled. The condenser was designed with 12 tubes in an array of three horizontalsand four verticals with a 2-in. horizontal and 1.5-in. vertical in-line pitch. By using effective additives, the condensation heat transfer rate can be augmented as much as 30% as compared with heat transfer that operated without additives under the same operating condition. The steam condensation,which occurred in our experiments while using effective additives, was mostly dropwise like. When heat transfer additives function effectively, the condensate-droplets become more dispersed and have a smaller shape than those produced without additives. These droplets, unlike traditional turbulence, start at the top portion of the condenser tubes and cover most of the tubes. Such a flow behavior can be explained by the Marangoni effect (in termsof thermodynamic equilibrium) in connection with obtained surface tension data. Furthermore, we extend our discussion to the dynamic effect of surface tension in the steam condensation process and propose a general criterionfor selecting effective additives. In our experiments, we noted that the use of heat transfer additives such as 2-ethyl-1-hexanol for steam condensation was highly effective. (C) 2001 Elsevier Science Ltd. All rights reserved.

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Documento generato il 30/11/20 alle ore 16:31:15