Heat transfer from supercritical carbon dioxide flowing in horizontal mini/micro circular tubes cooled at a constant temperature has been investigated experimentally. Six stainless steel circular tubes having inside-diameters of 0.50 mm, 0.70 mm, 1.10 mm, 1.40 mm, 1.55 mm, and 2.16 mm were tested. Measurements were carried out for the pressures ranging from 74 to 120 bar, the temperatures ranging from 20 to 110°C, and the mass flow rates ranging from 0.02 to 0.2 kg/min. It is found that the buoyancy effect was still significant, although supercritical CO2 was in forced motion through the horizontal tubes at Reynolds numbers up to 105. The experimental results also indicate that the existing correlations developed in the previous studies for large tubes deviate significantly from the experimental data for the present mini/micro tubes. Based on the experimental data, a correlation was developed for the axially averaged Nusselt number in terms of appropriate dimensionless parameters for forced convection of supercritical carbon dioxide in horizontal mini/micro tubes cooled at a constant temperature.

1.
Lorentzen
,
G.
, and
Pettersen
,
J.
,
1993
, “
A New Efficient and Environmentally Benign System for Car Air-Conditioning
,”
Int. J. Refrig.
,
16
, No.
1
, pp.
4
12
.
2.
Pettersen
,
J.
,
Hafner
,
A.
, and
Skaugen
,
G.
,
1998
, “
Development of Compact Heat Exchangers for CO2 Air-Conditioning Systems
,”
Int. J. Refrig.
,
21
, No.
3
, pp.
180
193
.
3.
McLinden, M., Klein, S. A., Lemmon, E. W., and Peskin, A. P., 1998, NIST Thermodynamic and Transport Properties of Refrigerants and Refrigerant Mixtures-REFPROP, Version 6.01, National Institute of Standards and Technology, USA.
4.
Krasnoshchekov
,
E. A.
,
Kuraeva
,
I. V.
, and
Protopopov
,
V. S.
,
1970
, “
Local Heat Transfer of Carbon Dioxide at Supercritical Pressure under Cooling Conditions
,”
Teplofiz. Vys. Temp.
,
7
, No.
5
, pp.
922
930
.
5.
Baskov
,
V. L.
,
Kuraeva
,
I. V.
, and
Protopopov
,
V. S.
,
1977
, “
Heat Transfer With the Turbulent Flow of a Liquid at Supercritical Pressure in Tubes under Cooling Conditions
,”
Teplofiz. Vys. Temp.
,
15
, No.
5
, pp.
96
102
.
6.
Jackson, J. D., Hall, W. B., Fewster, J., Watson, A., and Watts, M. J., 1975, “Heat Transfer to Supercritical Pressure Fluids,” U.K.A.E.A. A.E.R.E.-R 8158, Design Report 34.
7.
Lee
,
S. H.
, and
Howell
,
J. R.
,
1998
, “
Turbulent Developing Convective Heat Transfer in a Tube for Fluids Near the Critical Point
,”
Int. J. Heat Mass Transf.
,
41
, No.
10
, pp.
1205
1218
.
8.
Petrov
,
N. E.
, and
Popov
,
V. N.
,
1985
, “
Heat Transfer and Resistance of Carbon Dioxide Cooled in the Supercritical Region
,”
Thermal Engineering
,
32
, No.
3
, pp.
131
134
.
9.
Zhou, N., and Krishnan, A., 1995, “Laminar and Turbulent Heat Transfer in Flow of Supercritical CO2,Proceedings of the 30th National Heat Transfer Conference, Vol. 5, ASME, Portland, OR, pp. 53–63.
10.
Kakac, S., 1987, “The Effect of Temperature-Dependent Fluid Properties on Convective Heat Transfer,” Handbook of Single-phase Convective Heat Transfer, S. Kakac et al., eds., John Wiley & Sons, New York, pp. 18.1–18.56.
11.
Hall, W. B., 1971, “Heat Transfer Near the Critical Point,” Advances in Heat Transfer, Vol. 7, J. P. Hartnett and T. F. Irvine, Jr., eds., Academic Press, San Diego, CA, pp. 1–86.
12.
Polyakov, A. F., 1991, “Heat Transfer Under Supercritical Pressures,” Advances in Heat Transfer, 21, ed. J. P. Hartnett and T. F. Irvine, Jr., eds., Academic Press, San Diego, CA, pp. 1–53.
13.
Pettersen, J., Rieberer, R., and Leister, A., 2000, “Heat Transfer and Pressure Drop Characteristics of Supercritical Carbon Dioxide in Microchannel Tubes Under Cooling,” Proceedings, 4th IIR-Gustav Lorentzen Conference on Natural Working Fluids at Purdue, pp. 99–106.
14.
Adams
,
T. M.
,
Abdel-Khalik
,
S. I.
,
Jeter
,
S. M.
, and
Qureshi
,
Z. H.
,
1998
, “
An Experimental Investigation of Single-Phase Forced Convection in Microchannels
,”
Int. J. Heat Mass Transf.
,
41
, Nos.
6-7
, pp.
851
857
.
15.
Petukhov, B. S., 1970, “Heat Transfer and Friction in Turbulent Pipe Flow with Variable Physical Properties,” Advances in Heat Transfer, Vol. 6, J. P. Hartnett and T. F. Irvine, eds., Academic, San Diego, CA, pp. 504–564.
16.
Taylor, B. N., and Kuyatt, C. E., 1994, “Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results,” NIST Technical Note 1297, National Institute of Standards and Technology, USA.
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