Measurements that illustrate the enhancement of heat transfer caused by a bubble sliding under an inclined surface are reported. The data were obtained on an electrically heated thin-foil surface that was exposed on its lower side to FC-87 and displayed the output of a liquid crystal coating on the upper (dry) side. A sequence of digital images was obtained from two cameras: one that recorded the response of the liquid crystal and one that recorded images of the bubble as it moved along the heated surface. With this information, the thermal imprint of the bubble was correlated to its motion and position. A bubble generator that produced FC-87 bubbles of repeatable and controllable size was also developed for this study. The results show that both the microlayer under a sliding bubble and the wake behind the bubble contribute substantially to the local heat transfer rate from the surface. The dynamic behavior of the bubbles corresponded well with studies of the motion of adiabatic bubbles under inclined plates, even though the bubbles in the present study grew rapidly because of heat transfer from the wall and the surrounding superheated liquid. Three regimes of bubble motion were observed: spherical, ellipsoidal and bubble-cap. The regimes depend upon bubble size and velocity. A model of the heat transfer within the microlayer was used to infer the microlayer thickness. Preliminary results indicate a microlayer thickness of 40–50 μm for bubbles in FC-87 and a plate inclination of 12 deg.

Issue Section:
Bubbles, Particles, and Droplets
Keywords:
heat transfer, bubbles, flow measurement, Boiling, Enhancement, Heat Transfer, Phase Change, Thin Films
Topics:
Bubbles, Heat transfer, Temperature
1.
Cornwell
,
K.
,
1991
, “
The Influence of Bubbly Flow on Boiling From a Tube Bundle
,”
Int. J. Heat Mass Transf.
,
33
, pp.
2579
–
2584
.
2.
Cooper
,
M. G.
, and
Lloyd
,
A. J. P.
,
1969
, “
The Microlayer in Nucleate Pool Boiling
,”
Int. J. Heat Mass Transf.
,
12
, pp.
895
–
913
.
3.
Koffman
,
L. D.
, and
Plesset
,
M. S.
,
1983
, “
Experimental Observations of the Microlayer in Vapor Bubble Growth on a Heated Solid
,”
ASME J. Heat Transfer
,
105
, pp.
625
–
632
.
4.
Addlesee, A. J., Cornwell, K., and Peace, D. G., 1989, “Fluid Dynamics of Sliding Bubbles and Heat Transfer Implications,” Proc. Eurotherm Seminar 8, Pool Boiling, Paderborn, pp. 57–64.
5.
Addlesee
,
A. J.
, and
Cornwell
,
K.
,
1997
, “
Liquid Film Thickness Above a Bubble Rising Under an Inclined Plate
,”
Chem. Eng. Res. Des.
,
75
, pp.
663
–
667
.
6.
Addlesee, A. J., and Cornwell, K., 1999, “The Velocity of Bubbles Rising Under an Inclined Plate,” ImechE Conf. Trans., 6th UK National Conf. on Heat Transfer, pp. 231–236.
7.
Yan, Y., and Kenning, D. B. R., 1994, “Heat Transfer Near Sliding Vapor Bubbles in Boiling,” Proc., 10th International Heat Transfer Conference, pp. 195–200.
8.
Yan, Y., Kenning, D. B. R., Grant, I. A., and Cornwell, K., 1996, “Heat Transfer to Sliding Bubbles Under Plane and Curved Surfaces,” Fourth UK National Conf. On Heat Transfer, Manchester, IMechE, C510/118, pp. 295–299.
9.
Kenning, D. B. R., Bustnes, O. E., and Yan, Y., 2000, “Heat Transfer to a Sliding Vapor Bubble,” Proc. ASME Boiling 2000 Conf., 104, pp. 82–89.
10.
Qiu, D. M., and Dhir, V. K., 1999, “An Experimental Study of Heat Transfer During Sliding of Bubbles on Inclined Surfaces,” Proc. 5th ASME/JSME Joint Thermal Engineering Conference, San Diego, Paper AJTE99/6279.
11.
Thorncroft
,
G. E.
, and
Klausner
,
J. F.
,
1999
, “
The Influence of Vapor-Bubble Sliding on Forced Convection Boiling Heat Transfer
,”
ASME J. Heat Transfer
,
121
, pp.
73
–
79
.
12.
Bayazit, B. B., 2000, “A Thermographic Analysis of the Heat Transfer Mechanisms Generated by a Sliding Bubble,” Masters thesis, University of Houston, Houston, TX.
13.
Hay
,
J. L.
, and
Hollingsworth
,
D. K.
, 1996, “A Comparison of Trichromic Systems for Use in the Calibration of Polymer-Dispersed Thermochromic Liquid Crystals,” J. Exp. Thermal and Fluid Sci., 12, pp. 1–12.
14.
Hay
,
J. L.
, and
Hollingsworth
,
D. K.
, 1998, “Calibration of Micro-Encapsulated Liquid Crystals Using Hue Angle and a Dimensionless Temperature,” J. Exp. Thermal and Fluid Sci., 18, pp. 251–257.
15.
Dukle
,
N. M.
, and
Hollingsworth
,
D. K.
, 1996, “Liquid Crystal Images of the Transition from Jet-Impingement Convection to Nucleate Boiling, Part 1: Monotonic Distribution of the Convection Coefficient,” and “Part 2: Nonmonotonic Distribution of the Convection Coefficient,” J. Exp. Thermal and Fluid Sci., 12, pp. 274–297.
16.
Dalrymple, N. E., Dukle, N. M., and Hollingsworth, D. K., 1995, “The Behavior of a Boiling Front in Jet-Impingement Boiling,” Proc. of ASME/JSME Thermal Engineering Conference, 2, pp. 339–346.
17.
Maxworthy
,
T.
,
1991
, “
Bubble Rise Under an Inclined Plate
,”
J. Fluid Mech.
,
229
, pp.
659
–
674
.
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