Experimental and numerical investigation of turbulent flow heat transfer in a serpentine channel with multiple short ribbed passes and turning vanes

Detailed experimental and numerical investigations are conducted on the heat transfer, pressure loss and flow structure characteristics of a serpentine channel with multiple short ribbed passes and turning vanes, and the channel Reynolds numbers range from 10,000 to 60,000. The results are compared with the counterparts of a smooth three-pass serpentine channel and another one without turning vanes in the bend regions. The globally averaged heat transfer and the pressure loss characteristics of the three-pass serpentine channels were obtained by steady-state heat transfer experiments. The local heat transfer distributions of each ribbed pass were obtained by using transient liquid crystal thermography technique. Furthermore, the SST k-? turbulence model was adopted for the steady-state three-dimensional numerical simulations to examine the detailed flow characteristics in the three-pass channels. The experimental results show that within the studied Reynolds number range the ribbed channel with the turning vanes shows averaged Nusselt number ratios of 1.56?1.72 in the first pass, 2.05?2.18 in the second pass and 2.15?2.23 in the third pass respectively, which are correspondingly about 10% lower than those of the counterpart without the turning vanes. The total pressure loss of the serpentine channel with the turning vanes is reduced by 13.4%?48.4% compared to the case without the turning vanes. The experiments by the transient liquid crystal thermography indicate that the turning vanes in the bend regions appreciably improve the heat transfer uniformity in the second and third passes. The numerical simulations show similar heat transfer characteristics as the experiments for the ribbed serpentine channels, and further show that the turning vanes improve the flow structure in the bend regions, and reduce the flow separation in the second and third passes, which contributes a more uniform heat transfer in the three-pass serpentine channel.

Automated summary

The study indicates that adding turning vanes in the ribbed serpentine channels can significantly improve the heat transfer uniformity in the second and third passes, and reduce pressure loss.