Flow and Heat Transfer Mechanism and Optimization Design of Spirally Corrugated Tubes

Spirally corrugated tubes are widely used as high-efficiency heat transfer tubes in various industrial production fields due to their simple manufacturing, low cost, and bidirectional enhanced heat transfer ability. In this study, numerical simulations were conducted on the flow in multi-start spirally corrugated tubes with an equivalent inner diameter of D_i = 20 mm. The effects of starts value of 1–8, pitch ratio p/D_i of 1.5–3.0, ripple depth ratio e/D_i of 0.05–0.20, and Reynolds number Re of 5000–3000 on the heat transfer and resistance characteristics of the multi-start spirally corrugated tubes were studied, and the mechanism of heat transfer enhancement was demonstrated by field synergy theory. In addition, through the performance evaluation standard performance evaluation criteria (PEC), the optimization design of the multi-start spirally corrugated tube was achieved. The research results indicate that increasing the start value and ripple depth improves heat transfer performance despite higher flow resistance. As the pitch increases, the heat transfer performance decreases, and the flow resistance correspondingly decreases. When the start value is 8, p/D_i = 1.5, e/D_i = 0.20, and Re = 20,000, it is the optimal PEC value, equal to 1.764. This will be of great significance for the design, manufacturing, and practical application of spirally corrugated tubes.