The paper presents the results of an experimental study that was carried out to determine the Prandtl number influence on the thermal-hydraulic performance of enhanced tubes. The enhanced tubes were identical in all aspects, except the roughness height. Emphasis was placed on turbulent flow, with water as the working fluid. Experiments were performed for Prandtl numbers from 10.2 to 5.8. Data for friction factor were obtained under both isothermal and heating conditions. The study confirmed the strong influence of rib roughness on heat transfer and pressure drop increase. In addition, the results of the investigation strongly suggest that the optimum roughness is application specific, because it is dependent on Reynolds and Prandtl numbers. The results show that the presence of entrance effects and the influence of temperature on the friction factor of enhanced tubes may be significant. The experiments show that a rib height-to-diameter ratio of 0.02 provides the best overall performance for water at Pr = 10; while at Pr = 6.0, the optimum e/d depends on the Reynolds number.

Issue Section:
Forced Convection
Keywords:
Augmentation and Enhancement, Heat Exchangers, Refrigeration
Topics:
Heat transfer, Low temperature, Prandtl number, Turbulence, Water, Surface roughness, Friction, Fluids, Heat exchangers, Heating, Pressure drop, Refrigeration, Reynolds number, Temperature
1.
Bergles
A. E.
,
1988
, “
Some Perspectives on Enhanced Heat Transfer-Second-Generation Heat Transfer Technology
,”
ASME JOURNAL OF HEAT TRANSFER
, Vol.
110
, pp.
1082
–
1096
.
2.
Bergles, A. E., Blumenkrantz, A. R., and Taborek, J., 1974, “Performance Evaluation Criteria for Enhanced Heat Transfer Surfaces,” Heat Transfer 1974, JSME, Tokyo, Vol. II, pp. 239–243.
3.
Kalinin, E. K., 1974, “Tubular Heat Exchangers With Bilateral Heat Transfer Augmentation and Calculation of a Heat Exchanger Under Unsteady Operating Conditions,” Heat Exchangers: Design and Theory Source Book, N. Afgan and E. U. Schlunder, eds., Chap. 8, pp. 177–206.
4.
Kays, X. X., and Crawford, Y. Y., 1982, Convective Heat Transfer, 2nd ed., McGraw-Hill, New York.
5.
Kline
S. J.
, and
McClintock
F. A.
,
1953
, “
Describing Uncertainties in Single-Sample Experiments
,”
Mechanical Engineering
, Vol.
75
, Jan., pp.
3
–
8
.
6.
Li, H. M., Ye, K. S., and Tan, Y. K., and Deng, S. J., 1982, “Investigation on Tube-Side Flow Visulization, Friction Factors and Heat Transfer Characteristics of Helical-Ridging Tubes,” Heat Transfer 1982, Proc. 7th Int. Heat Transfer Conf., Vol. 3, Hemisphere Publishing Corp., Washington, DC, pp. 75–80.
7.
Marner
W. J.
,
Bergles
A. E.
, and
Chenoweth
J. M.
,
1983
, “
On the Presentation of Performance Data for Enhanced Tubes in Shell-and-Tube Heat Exchangers
,”
ASME JOURNAL OF HEAT TRANSFER
, Vol.
105
, pp.
358
–
365
.
8.
Mehta, M. H., and Raja, Rao, M., 1979, “Heat Transfer and friction Characteristics of Spirally Enhanced Tubes for Horizontal Condensers,” Advances in Enhanced Heat Transfer, San Diego, CA, pp. 11–22.
9.
Nakayama, M., Takahashi, K., and Daikoku, T., 1983, “Spiral Ribbing to Enhance Single-Phase Heat Transfer Inside Tubes,” Proc. ASME-JSME Thermal Engineering Joint Conf., Honolulu, HI, pp. 365–372.
10.
Petukhov, B. S., and Popov, V. N., 1963, “Theoretical Calculation of Heat Exchange and Frictional Resistance in Turbulent Flow in Tubes of an Incompressible Fluid With Variable Physical Properties,” High Temperature 1, pp. 69–83.
11.
Rabas, T. J., Bergles, A. E., and Moen, D. L., 1988, “Heat Transfer and Pressure Drop Correlations for Spirally Grooved (Rope) Tubes Used in Surface Condensers and Multistage Flash Evaporators,” Proc. National Heat Transfer Conference, ASME HTD-Vol. 96, pp. 693–704.
12.
Ravigururajan
T. S.
, and
Bergles
A. E.
,
1985
, “
General Correlations for Pressure Drop and Heat Transfer for Single-Phase Turbulent Flow in Internally Ribbed Tubes
,”
Augmentation of Heat Transfer in Energy Systems
, ASME HTD-Vol.
52
, pp.
9
–
20
.
13.
Ravigururajan
T. S.
, and
Bergles
A. E.
,
1986
, “
An Experimental Verification of General Correlations for Single Phase Turbulent Flow in Ribbed Tubes
,”
Advances in Heat Exchanger Design
, ASME HTD-Vol.
66
, pp.
1
–
11
.
14.
Thomas, L. C., 1992, Heat Transfer, Prentice-Hall, Inc., New Jersey.
15.
Webb, R. L., 1969, “Turbulent Heat Transfer in Tubes Having Two-Dimensional Roughness, Including the Effect of Prandtl Number,” Ph.D Thesis, University of Minnesota.
16.
Webb
R. L.
,
Eckert
E. R. G.
, and
Goldstein
R. J.
,
1971
, “
Heat Transfer and Friction in Tubes With Repeated-Rib Roughness
,”
Int. J. Heat Mass Transfer
, Vol.
14
, pp.
601
–
617
.
17.
Withers, J. G., 1973, “Heat Transfer Tube Having Multiple Internal Ridges,” U.S. Patent 3,779,312.
18.
Withers, J. G., 1980a, “Tube-Side Heat Transfer and Pressure Drop for Tubes Having Helical Internal Ridging With Turbulent/Transitional Flow of Single-Phase Fluid. Part 1. Single-Helix Ridging,” Heat Transfer Engineering 2, No. 1, pp. 48–58.
19.
Withers, J. G., 1980b, “Tube-Side Heat Transfer and Pressure Drop for Tubes Having Helical Internal Ridging With Turbulent/Transitional Flow of Single-Phase Fluid. Part 2. Multiple-Helix Ridging,” Heat Transfer Engineering 2, No. 2, pp. 43–50.
20.
Yorkshire Imperial Metals, 1982, “YIM Heat Exchanger Tubes: Design Data for Horizontal Rope Tubes in Steam Condensers,” Technical Memorandum 3, Yorkshire Imperial Metals, Ltd., Leeds, United Kingdom.
This content is only available via PDF.
Copyright © 1995
 by The American Society of Mechanical Engineers
You do not currently have access to this content.