A geometric study on shell side heat transfer and flow resistance of a six-start spirally corrugated tube

Heat transfer enhancement is of great importance for energy efficiency improvement. The utilization of spirally corrugated tubes is one of the efficient ways to strengthen heat transfer. In this article, based on a validated numerical model, the effects of geometric parameters of a six-start spirally corrugated tube, including the pitch p and the corrugation depth e, on the shell side heat transfer and flow resistance performance are numerically investigated, in high Reynolds number conditions ranging from 10,000 to 60,000. The shell side secondary flow velocity distribution, longitudinal vortex distribution, and temperature distribution of a six-start spirally corrugated tube are presented, respectively. In addition, the heat transfer and flow resistance characteristics are evaluated by comparing the Nusselt number and the flow resistance coefficient with these of smooth tubes. Results show that the utilization of six-start spirally corrugated tubes can enhance the heat transfer performance at the expense of an increase of the flow resistance. However, with the same geometric parameters, the Nusselt number increases and the flow resistance coefficient decreases as Reynolds number increases. With the pitch increasing, the Nusselt number and the flow resistance coefficient decrease at a fixed Reynolds number. In contrast, as the corrugation depth increasing, the Nusselt number changes irregularly, and the flow resistance coefficient increases. Finally, correlations for the shell side Nusselt number and flow resistance coefficient of the six-start spirally corrugated tube are established. This work is of significance for engineers and scientists focusing on the heat transfer and the flow resistance characteristics of spirally corrugated tubes and their applications.