An experimental study was undertaken to examine the enhancement in critical heat flux (CHF) provided by streamwise curvature. Curved and straight rectangular flow channels were fabricated with identical 5.0 × 2.5 mm cross sections and heated lengths of 101.6 mm in which the heat was applied to only one wall—the concave wall (32.3 mm radius) in the curved channel and a side wall in the straight. Tests were conducted using FC-72 liquid with mean inlet velocity and outlet subcooling of 0.25 to 10 m s−1 and 3 to 29°C, respectively. Centripetal acceleration for curved flow reached 315 times earth’s gravitational acceleration. Critical heat flux was enhanced due to flow curvature at all conditions but the enhancement decreased with increasing subcooling. For near-saturated conditions, the enhancement was approximately 60 percent while for highly subcooled flow it was only 20 percent. The causes for the enhancement were identified as (1) increased pressure on the liquid-vapor interface at wetting fronts, (2) buoyancy forces and (3) increased subcooling at the concave wall. Flow visualization tests were conducted in transparent channels to explore the role of buoyancy forces in enhancing the critical heat flux. These forces were observed to remove vapor from the concave wall and distribute it throughout the cross section. Vapor removal was only effective at near-saturated conditions, yielding the observed substantial enhancement in CHF relative to the straight channel.

1.
Collier, J. G., and Thome, J. R., 1994, Convective Boiling and Condensation, 3rd Ed., Clarendon Press, Oxford.
2.
Gambill
W. R.
, and
Green
N. D.
,
1958
, “
Boiling Burnout with Water in Vortex Flow
,”
Chemical Engineering Progress
, Vol.
54
, pp.
68
76
.
3.
Galloway
J. E.
, and
Mudawar
I.
,
1993
a, “
CHF Mechanism in Flow Boiling From a Short Heated Wall—Part I. Examination of Near-Wall Conditions with the Aid of Photomicrography and High-Speed Video Imaging
,”
International Journal of Heat and Mass Transfer
, Vol.
36
, pp.
2511
2526
.
4.
Galloway
J. E.
, and
Mudawar
I.
,
1993
b, “
CHF Mechanism in Flow Boiling From a Short Heated Wall—Part II. Theoretical CHF Model
,”
International Journal of Heat and Mass Transfer
, Vol.
36
, pp.
2527
2540
.
5.
Galloway
J. E.
, and
Mudawar
I.
,
1995
, “
A Theoretical Model for Flow Boiling CHF From Short Concave Heaters
,”
ASME JOURNAL OF HEAT TRANSFER
, Vol.
117
, pp.
698
707
.
6.
Gersey
C. O.
, and
Mudawar
I.
,
1995
a, “
Effects of Heater Length and Orientation on the Trigger Mechanism for Near-Saturated Flow Boiling Critical Heat Flux—I. Photographic Study and Statistical Characterization of the Near-Wall Interfacial Features
,”
International Journal of Heat and Mass Transfer
, Vol.
38
, pp.
629
641
.
7.
Gersey
C. O.
, and
Mudawar
I.
,
1995
b, “
Effects of Heater Length and Orientation on the Trigger Mechanism for Near-Saturated Flow Boiling Critical Heat Flux—II. CHF Model
,”
International Journal of Heat and Mass Transfer
, Vol.
38
, pp.
643
654
.
8.
Gu, C. B., Chow, L. C., and Beam, J. E., 1989, “Flow Boiling in a Curved Channel,” Heat Transfer in High Energy/High Heat Flux Applications, R. J. Goldstein, L. C. Chow, and E. E. Anderson, eds., ASME, New York, ASME HTD-Vol. 119, pp. 25–32.
9.
Hughes, T. G., and Olson, D. R., 1975, “Critical Heat Fluxes for Curved Surfaces During Subcooled Flow Boiling,” U.S. National Heat Transfer Conference, Vol. 3, San Francisco, CA, ASME, New York, pp. 122–130.
10.
Leland, J. E., and Chow, L. C, 1992, “Effect of Channel Height and Radius of Curvature on Forced Convective Boiling in a Rectangular Channel,” 30th Aerospace Sciences Meeting & Exhibit, Reno, NV.
11.
Wu, P. S., and Simon, T. W., 1994, “Critical Heat Flux and Subcooled Flow Boiling with Small Heated Regions on Straight and Concave-Curved Walls,” 10th International Heat Transfer Conference, Institute of Chemical Engineers, Rugby, UK, Vol. 7, pp. 569–574.
12.
Wu, P. S., and Simon, T. W., 1995, “Subcooled Flow Boiling Over a Thin, Low-Capacitance Surface on a Concave Wall,” ASME National Heat Transfer Conference, Portland, OR, Vol. 12, pp. 177–184.
13.
Zuber, N., Tribus, M., and Westwater, J. M., 1961, “The Hydrodynamic Crisis in Pool Boiling of Saturated and Subcooled Liquids,” International Developments in Heat Transfer: Proceedings of the 1961-62 International Heat Transfer Conference, Boulder, CO, ASME, New York, pp. 230–236.
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