Influence of hydrodynamic interactions among multiple bubbles on convective heat transfer in nucleate boiling

Takeyama, Mao (avtor), Zupančič, Matevž (avtor), Kunugi, Tomoaki (avtor)

To clear the effects of the hydrodynamic interactions among neighboring vapor bubbles on the saturated pool boiling heat transfer, artificial nucleation sites with several cavity arrangements were manufactured on the substrate surface and measured liquid temperatures near heated substrate by a miniature thermocouple probe with 10 kHz. The surface temperature of heated substrate was measured by an infrared camera with 1 kHz and bubble dynamics were simultaneously visualized by a high-speed video camera with 5 kHz and 10 kHz, respectively. The liquid temperature fluctuations, measured with micro thermocouple 100 %m and 10 %m above the substrate surface, were compared among each other and with the transient temperature fields obtained through IR measurements. Results showed that the hydrodynamic interaction among neighboring bubbles causes the liquid convection, that was only detected 100 %m above the boiling surface. Generally, the degree of liquid temperature fluctuations at 10 %m height and different arrangements of nucleation sites was under 1 K. Here the superheated sublayer in the vicinity of the boiling surface was generally not affected by the convection. Only when the coalescence from two neighboring nucleation sites occurred and the liquid-vapor interface nearly reached the substrate, a steep temperature drop over 2 K was detected. It was concluded that the viscous sublayer stably exists during boiling of water in lower heat flux conditions. To enhance the convective heat transfer in nucleate boiling, coalesced bubble needs to peel off the viscous sublayer during its deformation. Based on the measurements in this study, this peel-off effect only happens when the coalescence point is less than 1 mm above the heated surface.

• Jezik: Angleški jezik
• Ključne besede: nucleate boiling, bubble coalescence, superheated sublayer, convection effect, liquid temperature measurement, substrate temperature measurement
• Vrsta gradiva: Članek v reviji
• Tipologija: 1.01 - Izvirni znanstveni članek
• Organizacija: FS - Fakulteta za strojništvo
• Status publikacije: Objavljeno
• Različica publikacije: Recenzirani rokopis
• Leto izida: 2021
• Št. strani: Str. 1-11
• Številčenje: Vol. 128, art. 110449
• PID: 20.500.12556/RUL-127505
• UDK: 536.24
• ISSN pri članku: 0894-1777
• DOI: 10.1016/j.expthermflusci.2021.110449
• COBISS.SI-ID: 66639875
• Datum objave v RUL: 11.06.2021

Gradivo je del revije

• Naslov: Experimental thermal and fluid science
• Skrajšan naslov: Exp. therm. fluid sci.
• Založnik: Elsevier
• ISSN: 0894-1777
• COBISS.SI-ID: 170523

Licence

• Licenca: CC BY-NC-ND 4.0, Creative Commons Priznanje avtorstva-Nekomercialno-Brez predelav 4.0 Mednarodna
• Povezava: http://creativecommons.org/licenses/by-nc-nd/4.0/deed.sl
• Opis: Najbolj omejujoča licenca Creative Commons. Uporabniki lahko prenesejo in delijo delo v nekomercialne namene in ga ne smejo uporabiti za nobene druge namene.
• Začetek licenciranja: 01.10.2021

Sekundarni jezik

• Jezik: Slovenski jezik
• Ključne besede: mehurčkasto vrenje, koalescence mehurčkov, pregreta plast, konvektivni učinki, meritve temperature v kapljevini, meritve temperature na površini