ARTICLE:

• CONVECTION HEAT TRANSFER ACTIVE ENHANCEMENT BY MAGNETICALLY INDUCED LONGITUDINAL VORTICES  download article

Li-Jun Yang
School of Energy and Power Engineering, Key Laboratory of Condition Monitoring and Control for Power Plant Equipment of Ministry of Education, North China Electric Power University, Beijing 102206, China

Jian-Xun Ren
School of Aerospace, Department of Engineering Mechanics, Key Laboratory of Enhanced Heat Transfer and Energy Conservation of Ministry of Education, Tsinghua University, Beijing 100084, P. R. China

Xiao-Ze Du
School of Energy and Power Engineering, Key Laboratory of Condition Monitoring and Control for Power Plant Equipment of Ministry of Education, North China Electric Power University, Beijing 102206, China

Deng-Ying Liu
Beijing Key Laboratory of Energy Safety and Clean Utilization, North China Electric Power University, Beijing 102206; and Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing 100080, China

Yong-Ping Yang
School of Energy and Power Engineering, Key Laboratory of Condition Monitoring and Control for Power Plant Equipment of Ministry of Education, North China Electric Power University, Beijing 102206, China

ABSTRACT

The magnetic gradient field introduced to the convection heat transfer in channel can result in longitudinal vortices in fluid flows. The laminar flow and heat transfer characteristics of air in a rectangular channel confined to a magnetic bi-pole field and a quadrupole field were numerically investigated. The velocity and temperature fields were obtained and the friction coefficients and Nusselt numbers were compared at different Reynolds numbers and wall temperatures for both hydraulically and thermally developing and fully developed flows. Different longitudinal vortices were presented for the convection heat transfers in the magnetic bi-pole and quadrupole fields. The vortex-induced heat transfer enhancement was discussed by using Field Synergy Principle. The results show that the synergy between the flow and temperature fields can be improved by the magnetically induced longitudinal vortices. For hydraulically and thermally developing flows, the synergy between the flow and temperature fields in magnetic quadrupole field was superior to that in bi-pole field. For hydraulically and thermally fully developed flows however, the synergy between the flow and temperature fields in magnetic quadrupole field was worse than that in bi-pole field.

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