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Journal of Enhanced Heat Transfer

Impact factor: 0.400

ISSN Print: 1065-5131
ISSN Online: 1563-5074

Journal of Enhanced Heat Transfer

DOI: 10.1615/JEnhHeatTransf.v11.i4.80
pages 307-314

Numerical Study on Low Reynolds Number Convection in Alternate Elliptical Axis Tube

Ji-An Meng
School of Aerospace, Department of Engineering Mechanics, Education Ministry Key Lab of Enhanced Heat Transfer and Energy Conservation, Tsinghua University, Beijing 100084, China
Xingang Liang
Tsinghua University
Zhi-Xin Li
School of Aerospace, Department of Engineering Mechanics, Education Ministry Key Lab of Enhanced Heat Transfer and Energy Conservation, Tsinghua University, Beijing 100084, China
Zengyuan Guo
Education Ministry Key Lab of Enhanced Heat Transfer and Energy Conservation, Tsinghua University, Beijing 100084, China
Professor Guo was born on 28 February 1936 in Jiangsu Province, China. He graduated from Tsinghua University in 1959. He has worked in Tsinghua University, Beijing, China ever since, a tenure of over 50 years. Professor Guo’s research has been mainly concerned with thermofluid mechanics, micro/nanoscale heat transfer, thermal system optimization and efficient thermal transport. He developed the concepts of thermal drag, thermal drive, thermal displacement, and thermal instability which were presented in his keynote lectures at the 8th and 9th International Heat Transfer Conferences and in a chapter on "Thermally Induced Effects on Fluid Flow" in the Annual Review of Heat Transfer, vol. 5, 1994. Professor Guo’s research is also related to the Microscale and nanoscale heat transfer. In his keynote lecture at the International Conference on Transport Phenomena at Microscale in Canada in 2000 and at the 12th International Heat Transfer Conferences in France in 2002, Professor Guo first revealed that the microscale heat transfer size effect on the flow and heat transfer correlations is attributed to the variation of the dominant factors, such as the flow compressibility, surface roughness, and axial conduction in the tube wall, as the scale decreases even though the continuum assumption is still applicable. He was awarded the ICMM 2005 Lifetime Contribution Award in the field of Heat and Mass Transfer due to his pioneering contributions through original research related to micro/nanoscale heat transfer. In the last decade, Professor Guo has mainly focused his research of effective utilization of thermal energy. He proposed the field synergy principle for the optimization of convective heat transfer and introduced the physical quantity "entransy" to represent the physical nature of the field synergy principle, by analogy between thermal and electrical transport. The dissipation of entransy can be used to define the efficiencies of heat transfer processes and to establish the extremum principle of entransy dissipation for heat transfer optimization because it represents the irreversibility of heat transfer not related to heat-work conversions. In recent years, Professor Guo has focused his interest on the nature of heat. He proposed the Thermomass theory, using Einstein’s mass-energy relevance and proposed a general heat conduction law that includes various heat conduction models, such as the Fourier model and C-V model as special cases.

ABSTRACT

This work numerically investigates the convection of the novel alternate elliptical axis tube by FLUENT 6.0 with laminar, Reynolds stress, and RNG k-ε models. The Nusselt numbers are found to be increased 100−500% for Re=500−2300 with low cost in resistance increase. The enhancement is due to the multi-longitudinal vortices. The comparison with experiments for Re = 500−10,000 shows that the Nusselt number obtained from different models all agree well with experiments. As for the resistance coefficient prediction, the Reynolds stress model is very close to the experiments for Re = 500−2500, and the RNG k-ε model is very close to experiments for Re < 4000.