Experimental studies of boiling performance in curved channels with a two-phase approach flow
- Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Mechanical Engineering
Experimental studies of flow boiling heat transfer on a small heater surface (3mm x 3mm) using FC-72 has been performed. Two channel geometries were compared; a straight channel and a curved channel with the heated patch on the concave wall at the 90{degree} of bend location. The main focus of this study was on the curvature effect under (1) near-saturation conditions of a pure fluid and (2) conditions where there was dissolved, non-condensable gas in the liquid and the approach flow became a two-phase mixture. This study is a continuation of a previous study conducted with higher levels of subcooling. The results show that at a given flow velocity and subcooling, critical heat flux, CHF, is higher in the curved flow than in the straight flow with a difference which grows as saturation conditions are approached. When dissolved gases are introduced to fluid which is maintained at 7 C below the pure-fluid saturation temperature, the approach flow becomes a two-phase mixture and the increase in CHF due to curvature becomes stronger. For a given mass flow rate, CHF decreases with increasing dissolved gas content in the straight flow case, whereas in the curved-flow case, the opposite trend is observed. In the curved flow case a cross-stream pressure gradient due to streamline curvature tends to carry bubbles away from the heated, concave wall. This results in higher CHF values in the concave-curved flow case than in the straight flow case.
- Sponsoring Organization:
- National Science Foundation, Washington, DC (United States)
- OSTI ID:
- 445440
- Report Number(s):
- CONF-950828--; ISBN 0-7918-1713-X
- Country of Publication:
- United States
- Language:
- English
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