Abstract
The utilization of V-spirally corrugated tubes has attracted the attention of many researchers recently. As typical enhancement techniques of heat transfer, they combined the merits of roughness, turbulators and enhanced surface. This paper mainly studies the influence of depth ratio (DR = 0.039–0.199), pitch ratio (PR = 2.37–4.77), and various numbers of starts (N = 4,6) on the flow and heat transfer behavior of V-spirally corrugated tubes in the turbulent flow region (10000 ⩽ Re ⩽ 40000). It employs numerical simulation techniques to obtain the heat transfer performance and resistance characteristics. A comparison is made between enhanced tubes and smooth tube considering evaluation parameters, including Nusselt number ratio and fraction factor. On the basis of investigated results, an analysis is made to distinguish the merits and disadvantages of the new-design enhanced tubes on the flow and heat transfer behavior. The computational results reveal that they enhance heat transfer to varying degrees, and the fluid fields differ. Both the six-start V-spirally corrugated tube and four-start V-spirally corrugated tube have larger Nusselt number than smooth tube under the same working condition and the six-start is better. The Nusselt number increases as Reynolds number increases or pitch decreases. Besides, the six-start V-spirally corrugated tube with depth ratio = 0.118 has the largest Nusselt number, which is larger than smooth tube by around 31.3%.
