DOI: 10.1615/ICHMT.2014.IntSympConvHeatMassTransf
ISBN Print: 978-1-56700-356-7
ISSN Online: 2642-3499
ISSN Flash Drive: 2642-3502
BOILING OF OIL-IN-WATER EMULSIONS IN A SQUARE CAPILLARY
摘要
In this study, we explore the usage of oil-in-water emulsions as the working fluid that undergoes phase change in heat-transfer device. The heat transfer characteristics are examined experimentally for boiling of emulsions of "soluble oil"-in-water in a square capillary. Even though only a very tiny amount of oil is added, we find that vaporization of water as the continuous phase in the emulsion exhibits very distinctive phenomena. Usually, the superheat associated with incipient boiling for emulsion is drastically augmented and boiling heat transfer is improved comparing to the case of water alone. As the mass fraction of "soluble oil" increases, initial boiling superheat gradually decreases. This may be attributed to the rise in the average diameter of oil droplets. We find that vapor bubble can emerge from the heated sidewall of the capillary, or from the interface of the two phases once boiling starts. Moreover, larger capillary leads to the deterioration of heat transfer and the benefit of using an emulsion in phase-change application disappears. The outcome of the current study provides a valuable insight into understanding the unique features of emulsion boiling in microscale.