Developing Turbulent Convective Heat Transfer in Helical Pipes

Abstract

Abstract A fully elliptic numerical study has been carried out to investigate three-dimensional turbulent developing convective heat transfer in helical pipes with finite pitches. The k-ε standard two-equation turbulence model is used to simulate turbulent flow. The turbulent flow and heat transfer are assumed to develop simultaneously. Uniform inlet velocity and constant wall temperature conditions are applied. The governing equations are solved by a Control-Volume Finite Element Method (CVFEM). Numerical results have been compared to the existing experimental data, and a good agreement has been obtained. The results presented in this paper cover a Reynolds number range of 2.5 × 104–1.0 × 105, a pitch range of 0.0–0.6, and a curvature ratio range of 0.025–0.050. The developments of effective thermal conductivity, temperature fields, and local and average Nusselt numbers are given and discussed. It has been found that the examined parameters exert complex effects on the developing thermal fields and heat transfer in the helical pipes. The Nusselt numbers for the helical pipes are oscillatory before the flow is fully developed, especially for the case of a relatively large curvature ratio.