Heat Transfer Study of a Hybrid Smooth and Spirally Corrugated Tube

Due to the merits of higher heat transfer efficiency, spirally corrugated tubes are widely used in a range of applications for heat transfer enhancement, especially in coaxial heat exchangers. This article studied a novel hybrid smooth and six-start spirally corrugated tube and focused on its heat transfer performance as well as its pressure drop. Firstly, we focused on the secondary flow derived from the centrifugal force due to the continuous spiral structure, and discovered the flow patterns of fluids in the hybrid tube. In this part, we applied models with different lengths of the corrugation part. Then, the corrugation parts connected with a smooth part can be arranged in identical rotation or opposite rotation of the corrugations, where the fluid affected by the corrugation part is still whirling. For the above different models, both heat transfer and pressure drop performances of two corrugation arrangements are investigated. This work reveals the enhanced heat transfer mechanism of the hybrid smooth and spirally corrugated tube and should be of interest to researchers in heat transfer issues of corrugated tubes.