Numerical study of characteristic influence on heat transfer of supercritical CO2 in helically coiled tube with non-circular cross section

The RNG K - epsilon turbulence enhanced wall treatment model is used to investigate the characteristic influence of supercritical CO2 on cooling heat transfer and pressure drop in the horizontal helically coiled tube with non-circular cross section. The comparisons of heat transfer coefficient and pressure drop are operated when the cross section is non-circular. With the increase of polygon edge number, the heat transfer and pressure drop increase, but the increase range gradually decreases. When the polygon edge number increases to a certain extent, the pressure drop decreases. Then the influence of the characteristic parameters pitch P, diameter d and radius R of helically coiled tube on the flow and heat transfer with non-circular cross section are studied. The results show that under the action of main flow and secondary flow, with the increase of pitch P, diameter d and radius R, the heat transfer decreases and the change of pressure drop is different. Based on the numerical simulation results, the curvature parameters are introduced in the Nusselt number correlation in the case of supercritical CO2 cooling heat transfer in octagon cross section helically coiled tubes, which has high accuracy. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The study investigated the influence of supercritical CO2 on cooling heat transfer and pressure drop in horizontal helically coiled tube with non-circular cross section. It was found that with the increase of polygon edge number, heat transfer and pressure drop increase, but the range of increase gradually decreases; when the polygon edge number reaches a certain extent, pressure drop decreases. Additionally, the increase in pitch P, diameter d, and radius R leads to a decrease in heat transfer, with different effects on pressure drop.