172 L. N. ZHANG ET AL.

Figure 12. Heat flux effects on Nusselt number of square

array rod bundle.

Figure 13. Comparison of square array rod bundle with

triangular array rod bundle.

with increasing heat flux. The heat transfer deterioration

takes place earlier with higher heat flux, whereas Nusselt

number appeared two peaks under lower heat flux.

The heat transfer effect of supercritical CO2 is better

than that of supercritical water. The effect of mass flux

on Nusselt number is more obvious than heat flux. The

Nusselt number is higher under larger mass flux, espe-

cially across the pseudocritical temperature. The heat

transfer effect with triangular array rod bundles is better

than that of square array rod bundles under the same heat

flux and mass flux.

6. Acknowledgments

This work was supported by the National Natural Sci-

ence Foundation of China (51076145). The authors

would like to thank teachers of Thermal Energy Engi-

neering Research Center of Zhengzhou University.

7. References

[1] K. Hyungrae, Y. K. Hwan, J. H. Song et al., “Heat Trans-

fer to Supercritical Pressure Carbon Dioxide Flowing

Upward through Tubes and a Narrow Annulus Passage,”

Progress in Nuclear Energy, Vol. 50, No. 2-6, 2008, pp.

518-525. doi:10.1016/j.pnucene.2007.11.065

[2] S. M. Liao and T. S. Zhao, “An Experimental Investiga-

tion of Convection Heat Transfer to supercritical Carbon

Dioxide in Miniature Tubes,” International Journal of

Heat and Mass Transfer, Vol. 45, No. 25, 2002, pp.

5025-5034. doi:10.1016/S0017-9310(02)00206-5

[3] C. B. Danga and E. J. Hihara, “In-Tube Cooling Heat

Transfer of Supercritical Carbon Dioxide. Part 1: Ex-

perimental Measurement,” International Journal of Re-

frigeration, Vol. 27, No. 7, 2004, pp. 736-747.

doi:10.1016/j.ijrefrig.2004.04.018

[4] M. Sharabi, W. Ambrosini, S. He et al., “Prediction of

Turbulent Convective Heat Transfer to a Fluid at Super-

critical Pressure in Square and Triangular Channels,”

Annals of Nuclear Energy, Vol. 35, No. 6, 2008, pp.

993-1005. doi:10.1016/j.anucene.2007.11.006

[5] P. X. Jiang, Y. Zhang and R. F. Shi, “Experimental and

Numerical Investigation of Convection Heat Transfer of

CO2 at Supercritical Pressures in a Vertical Mini-Tube,”

International Journal of Heat and Mass Transfer, Vol. 51,

No. 11-12, 2008, pp. 3052-3056.

doi:10.1016/j.ijheatmasstransfer.2007.09.008

[6] L. X. Cheng, G. Ribatskia and J. R. Thome, “Analysis of

Supercritical CO2 Cooling in Macro- and Micro-Chan-

nels,” International Journal of Refrigeration, Vol. 31, No.

8, 2008, pp. 1-16. doi:10.1016/j.ijrefrig.2008.01.010

[7] M. van der Kraan, M. M. W. Peeters, M. V. Fernandez

Cid, G. F. Woerlee, W. J. T. Veugelers and G. J. Wit-

kamp, “The Influence of Variable Physical Properties and

Buoyancy on Heat Exchanger Design for Near- and Su-

percritical Conditions,” The Journal of Supercritical

Fluids, Vol. 34, No. 1, 2005, pp. 99-105.

doi:10.1016/j.supflu.2004.10.007

[8] J. K. Kim, H. K. Jeon and J. S. Lee, “Wall Temperature

Measurement and Heat Transfer Correlation of Turbulent

Supercritical Carbon Dioxide Flow in Vrtical Circu-

lar/Non-Circular Tubes,” Nuclear Engineering and De-

sign, Vol. 237, No. 15-17, 2007, pp. 1795-1802.

doi:10.1016/j.nucengdes.2007.02.017

[9] S. He, W. S. Kim and J. H. Bae, “Assessment of Per-

formance of Turbulence Models in Predicting Supercriti-

cal Pressure Heat Transfer in a Vertical Tube,” Interna-

tional Journal of Heat and Mass Transfer, Vol. 51, No.

19-20, 2008, pp. 4659-4675.

doi:10.1016/j.ijheatmasstransfer.2007.12.028

[10] V. Gnielinski, “New Equations for Heat and Mass Trans-

fer in Turbulent Pipe and Channel Flow,” International

Chemical Engineering, Vol. 16, No. 2, 1976, pp. 359-68.

Copyright © 2011 SciRes. EPE