About features of condensation on the heat exchange surfaces with different contact angles wetting


Аuthors

Gavrish A. S.

NTUU ”Igor Sikorskiy KPI”, Kiev Ukraine

e-mail: andrew_gavrish@ukr.net

Abstract

A great number of various factors affects the condensation process. They include selection of the coolant, condensation surface material, lyophobization method, etc. The shape, size and orientation in space may also be an essential factor.

Various data analysis for one of the condensation mechanism primary characteristics, namely the contact angle of wetting was performed.The wetting angle hysteresis phenomenon and variation range of inflow wetting angles and outflow wetting angles were considered for various coolants and heat exchange surfaces types. The possibility of obtaining super hydrophobic, hydrophobic, and super-hydrophilic heat transfer surfaces along with the existing hydrophilic surfaceswas considered as well. The coexistence of various types of condensate compositions herewith can be characterized by the conditional process cycle. The contact angles hysteresis (static equilibrium, inflow and outflow) for the well-known types of coolants and heat exchange surfaces is leveled while transition to the super hydrophobic surfaces. The description of variety of condensation processes, performed applying the conditional cycle concept, acquires a number of specifics for the super hydrophobic surfaces. The empirical formulas for computing the ranges of inflow and outflow angles depending on the contact angle of wetting value were considered.

Recently, the progress has been made in obtaining super hydrophobic surface coatings not only for copper and copper alloys, but also for aluminum, aluminum alloys and steel. However, the coating persistence, including its running under the heat radiation impact, may affect the wetting angle, varying it significantly while this surface operating. This does not exclude herewith the possibility of transition from the super hydrophobic surface properties to simply hydrophobic properties, and then to the hydrophilic down to super hydrophilic and vice versa. All this affects the condensation process mechanism, finding its manifestation in the conditional condensation cycle.

It is advantageous to perform the analysis of the accumulated theoretical and experimental material along the two interconnected lines. One of these lines is studying the process mechanism, which determines its micro level. The other line consists in studying the process macro level, and eventually its intensity.

Keywords:

contact angle, conditional condensation cycle, hydrophilic behavior, hydrophobic behavior

References

  1. Isachenko V.P. Teploobmen pri kondensatsii [Heat transfer during condensation]. Moscow: Energia, 1981. 240 p. In Russ.

  2. Tanasawa I. Advances in condensation heat transfer. Advances in Heat Transfer, 1991, vol. 21, pp. 55–139.

  3. Tanasava I. Status and future directions in the study of condensation drip. Nihon Kikai Gakkai rombunsyu, 1982, vol.48, no. 429, pp. 835–843.

  4. Filippov G.A., Saltanov G.A., Kukushkin A.N. Gidrodinamika i teplomasoobmen v prisutstvii poverkhnostno-aktivnykh veshhestv [Hydrodynamics and heat-mass transfer in the presence of surfactants]. Moscow: Energoatomizdat, 1988. 184 p. In Russ.

  5. Boinovich L.B., Emelyanenko A.M. Hydrophobic materials and coatings: Principles of design, properties and applications. Russian Chemical Reviews, 2008, vol. 77, no. 7, pp. 583–600. DOI: 10.1070/RC2008v077n07ABEH003775

  6. Boinovich L.B., Emelyanenko A.M., Khodan A.N., Domantovskii A.G., Miller A.B., Potapov Y.F. Antiicing performance of superhydrophobic coatings on aluminum and stainless steel. https://elibrary.ru/pic/1pix.gif Russian Chemical Bulletin, 2013, vol. 62, no. 2, pp. 380–387 DOI: 10.1007/s11172-013-0049-6

  7. Zheng L., Wang Y-X., Plawsky J.L., Wayner P.C. Effect of curvature, contact angle, and interfacial sub cooling on contact line spreading in a micro drop in dropwise condensation. Langmiur, 2002, no. 18, pp. 5170–5177.

  8. Lau K.K.S., Bico J., Teo K.B.K., Chhowalla M., Amaratunga G.A.J., Milne W.I., McKinley G.H., Gleason K.K. Superhydrophobic carbon nanotube forests. Nano Letters, 2003, vol. 3, no. 12, pp. 1701–1705.

  9. Popov V.G. On the hysteresis of the contact angle of droplets (bubbles). High Temperature, 1991, vol. 29. no. 3, pp. 420–429.

  10. Gavrish A.S., Rifert V.G., Sardak A.I. Analysis of the influence of drop diameters on the intensity of heat transfer in dropwise condensation. Journal of Engineering Physics and Thermophysics, 1994, vol. 66, no. 6, pp. 593–597. https://doi.org/10.1007/BF00867956

  11. Gavrish A.S., Gavrish S.A. Ob osobennostyakh kraevogo ugla smachivaniya i mekhanizma protsessa kondensatsii [On the features of the wetting angle and the mechanism of the condensation process]. Trudy RNKT-4 — Proceedings of the Fourth Russian National Conference on Heat Exchange (RNCT-4), 2006, vol. 5, pp. 77–80. In Russ.

  12. Gavrish A.S. O supergidrofobnykh poverkhnostyakh i mekhanizme protsessa kondensatsii [About superhydrophobic surfaces and the mechanism of the condensation process]. Materialy Mezhdunarodnoj konferentsii SPTEH — Proceedings of International Conference «Problems of Thermal Physics and Power Engineering», 2017, vol. 1, pp. 277–278. In Russ.

  13. Gavrish A.S. O sovremennykh poverkhnostyakh teploobmena, kraevykh uglakh i uslovnom tsikle kondensatsii [About modern heat exchange surfaces, boundary corners and conventional condensation cycle]. Trudy RNKT-7 — Proceedings of the Seventh Russian National Conference on Heat Exchange (RNCT-7), 2018, vol. 2, pp. 35–38. In Russ.

  14. Croix J.M., Casset R., Camus R. Etude de condensation en gouttes par promoteurs organiques. Lyon: SETRE, 1978. 32 p.

  15. Xuehu M., Dunqi X., Jifand L. A study of dropwise condensation on the ultra-thin polymer surfaces. International Heat Transfer Conference, Brighton, UK, 1994, vol. 3, P. 359–364.

  16. Kim K., Vemuri S., Bell T., Govindaraju S. Advanced heat exchangers using tunable nanoscale-molecular assembly (Innovative concept phase — 1). Nanoscience program university of Nevada, Nevada ventures, Reno, 2004. N DE-FG26-02NT41543. P. 1–42.

  17. Gavrish A.S. O nekotorykh aspektakh polucheniya zashhitnykh pokrytij . nesmachivaemykh kondensatsionnykh poverkhnostej [On some aspects of obtaining protective coatings. non-wetted condensation surfaces]. Trudy RNKT-7 — Proceedings of the Seventh Russian National Conference on Heat Exchange (RNCT-7), 2018, vol. 2, pp. 31–34. In Russ.

  18. Gavrish A.S., Shevchenko А.N., Misyura T.A. O perspektivakh primeneniya supergidrofobnykh poverkhnostej [On superhydrophobic surfaces’ application perspectives]. Teplovye protsessy v tekhnike — Thermal processes in engineering, 2018, vol. 10 no. 1-2, pp. 84–89. In Russ.

  19. Gavrish A.S., Gavrish S.A., Khristyuk I.N. O primeneniya poverkhnostno-aktivnykh veshhestv v teploobmennikakh-kondensatorakh tipa RTА [On the application of surfactants in collapsible heat exchangers-condensers]. Teplovye protsessy v tekhnike — Thermal processes in engineering, 2016, vol. 8, no. 10, pp. 461–465. In Russ.

  20. Gavrish A.S., Zatirka N.O., Galchenko I.V. O primenenii veshhestv Gidroehffekt-Nanoprotek v teploobmennykh apparatakh [About application of Hydroeffect-Nanoprotec substances in heat exchangers]. Teplovye protsessy v tekhnike — Thermal processes in engineering, 2015, vol. 7, no. 10, pp. 449–453. In Russ.

mai.ru — informational site of MAI

Copyright © 2009-2024 by MAI