Experimental study on flow boiling heat transfer in an extremely small tube

Haruhiko Ohta, Koichi Inoue, Yuichiro Shimada

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Citations (Scopus)

Abstract

Flow boiling heat transfer in a single small tube is investigated by using FC72 as a working fluid. The heat transfer coefficients are measured in the ranges of heat flux 2-24kW/m2 and mass velocity 100-400kg/m 2s under the condition of near atmospheric pressure. Test tube, made of stainless steel, has an inner diameter of 0.51mm and a heated length of 200mm. The tube is located horizontally in a vacuum chamber to reduce the heat loss and to minimize the time to obtain data regarded as that of steady state. In the single-phase region, heat transfer coefficients due to forced convection are in good agreement with the values from the conventional theories. In the saturated region, measured heat transfer characteristics are quite different depending on whether the test liquid is deaerated or not deaerated before the experiments. By using deaerated liquid, three different heat transfer regimes are observed: In the first regime, the heat transfer is dominated by nucleate boiling in low vapor quality, and the heat transfer is deteriorated or enhanced depending on the channel confinement and heat flux. In the second regime, the heat transfer is dominated by two-phase forced convection in moderate quality as is well known for the tubes of normal size. In the third regime, the heat transfer is dominated again by two-phase forced convection, but is deteriorated in high quality. One or two regimes can disappear or become unclear depending on the conditions of flow and heating. The effects of vapor quality and mass velocity on the heat transfer characteristics due to two-phase forced convection in the moderate vapor quality are clarified in the experimental ranges tested. And a reason for the gradual heat transfer deterioration observed in high quality is discussed based on the liquid-vapor behaviors inherent in small diameter tubes.

Original languageEnglish
Title of host publicationProceedings of the 4th International Conference on Nanochannels, Microchannels and Minichannels, ICNMM2006
Pages105-114
Number of pages10
Publication statusPublished - Dec 1 2006
Event4th International Conference on Nanochannels, Microchannels and Minichannels, ICNMM2006 - Limerick, Ireland
Duration: Jun 19 2006Jun 21 2006

Publication series

NameProceedings of the 4th International Conference on Nanochannels, Microchannels and Minichannels, ICNMM2006
Volume2006 A

Other

Other4th International Conference on Nanochannels, Microchannels and Minichannels, ICNMM2006
CountryIreland
CityLimerick
Period6/19/066/21/06

All Science Journal Classification (ASJC) codes

  • Engineering(all)

Fingerprint Dive into the research topics of 'Experimental study on flow boiling heat transfer in an extremely small tube'. Together they form a unique fingerprint.

  • Cite this

    Ohta, H., Inoue, K., & Shimada, Y. (2006). Experimental study on flow boiling heat transfer in an extremely small tube. In Proceedings of the 4th International Conference on Nanochannels, Microchannels and Minichannels, ICNMM2006 (pp. 105-114). (Proceedings of the 4th International Conference on Nanochannels, Microchannels and Minichannels, ICNMM2006; Vol. 2006 A).