Dependence of Conjugate Heat Transfer in Ribbed Channel on Thermal Conductivity of Channel Wall: An LES Study

Joon Ahn, Jeong Chul Song and Joon Sik Lee
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Joon Ahn: School of Mechanical Engineering, Kookmin University, Seoul 02707, Korea
Jeong Chul Song: School of Mechanical and Aerospace Engineering, Seoul National University, Seoul 08826, Korea
Joon Sik Lee: School of Mechanical and Aerospace Engineering, Seoul National University, Seoul 08826, Korea

Energies, 2021, vol. 14, issue 18, 1-18

Abstract: A series of large eddy simulations was conducted to analyze conjugate heat transfer characteristics in a ribbed channel. The cross section of the rib is square and the blockage ratio is 0.1. The pitch between the ribs is 10 times the rib height. The Reynolds number of the channel is 30,000. In the simulations, the effect of the thermal resistance of the solid wall of the channel on convective heat transfer was observed in the turbulent flow regime. The numerical method used was based on the immersed boundary method and the concept of effective conductivity is introduced. When the conductivity ratio between the solid wall and the fluid ( K *) exceeded 100, the heat transfer characteristics resembled those for an isothermal wall, and the cold core fluid impinging and flow recirculation mainly influenced the convective heat transfer. For K * ≤ 10, the effect of the cold core fluid impinging became weak and the vortices at the rib corners strongly influenced the convective heat transfer; the heat transfer characteristics were therefore considerably different from those for an isothermal wall. At K * = 100, temperature fluctuations at the upstream edge of the rib reached 2%, and at K * = 1, temperature fluctuations in the solid region were similar to those in the fluid region. The rib promoted heat transfer up to K * = 100, but not for K * ≤ 10. The Biot number based on the channel wall thickness appears to adequately explain the variation of the heat transfer characteristics with K *.

Keywords: ribbed channel; large eddy simulation; immersed boundary method; conjugate heat transfer; thermal conductivity ratio (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2021
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (3)

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