Improvement of nucleate boiling heat transfer characteristics by using immiscible mixtures

Shota Kita, Shunsuke Onishi, Yuta Fukuyama, Haruhiko Ohta

Research output: Contribution to conferencePaper

1 Citation (Scopus)

Abstract

The increase of critical heat flux, the reduction of surface temperature, the operation at pressure larger than the atmospheric to avoid the air mixing, and the reduction of surface temperature overshoot at the boiling incipience are fundamental requirements for the development of high-performance cooling systems by the application of boiling phenomena. The present authors found the nucleate boiling of immiscible mixtures to satisfy all of the above requirements [1], however, its knowledge has not been clarified yet. Pool boiling experiments for five immiscible mixtures, FC72/water, Novec649/water, Novec7200/water, FC72/n- Propanol, and FC72/i-Propanol, are performed at atmospheric pressure. When the thickness of more-volatile liquid with higher density on a horizontal heating surface is very small, a new phenomenon of "intermediate burnout" accompanied by a small jump of surface temperature is observed, and the heat transfer mode is changed from the nucleate boiling of more-volatile liquid with higher density to the natural convection or nucleate boiling of less-volatile liquid of lower density. The heat transfer due to nucleate boiling of lessvolatile liquid is enhanced by the generated vapor of more-volatile component, which results in the reduction of surface temperature. Moreover, CHF is increased by high subcooling of less-volatile liquid compressed by the high vapor partial pressure of more-volatile component. No serious overshoot at the boiling incipience is observed if the more-volatile liquid with higher density is contacting the horizontal heating surface before heating. This trend is especially important for e.g. The cooling of inverters for electric vehicles with a large heat generation during the acceleration.

Original languageEnglish
Publication statusPublished - Jan 1 2014
Event15th International Heat Transfer Conference, IHTC 2014 - Kyoto, Japan
Duration: Aug 10 2014Aug 15 2014

Other

Other15th International Heat Transfer Conference, IHTC 2014
CountryJapan
CityKyoto
Period8/10/148/15/14

All Science Journal Classification (ASJC) codes

  • Mechanical Engineering
  • Condensed Matter Physics

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    Kita, S., Onishi, S., Fukuyama, Y., & Ohta, H. (2014). Improvement of nucleate boiling heat transfer characteristics by using immiscible mixtures. Paper presented at 15th International Heat Transfer Conference, IHTC 2014, Kyoto, Japan.