关键词: 层流换热 ,  螺旋管 ,  热力性能 ,  数值模拟

Abstract: A numerical method for simulating the developments and distributions of heat transfer and flow fields was proposed. The effects of Reynolds number, curvature ratio, and coil pitch on the average friction factor, average Nusselt number at different axial cross-sections and the total entropy generation rate in a helical coiled tube with uniform heat flux was presented when Reynolds number is 200~1 000, dimensionless pitch 0.1~0.2 and dimensionless curvature ratio 0.1~0.3. The results show that the effect of the secondary flow is enhanced with the increase of turning angle, the maximum velocity perpendicular to axial cross section shifts toward the outer side of helical coiled tube and two Dean roll cells appear with the increase of axial turning angle. Furthermore, the average friction factor, average Nusselt number at different axial cross-sections and the total entropy generation rate present different characteristics when the Reynolds number, curvature ratio and pitch change. Compared with the curvature ratio, the pitch has relatively little influence on convective heat transfer performance and the total entropy generation. In the meantime, the entropy generation caused by viscous flow is much less than that caused by heat transfer and can be neglected.

Key words: Laminar flow convection ,  Helical coiled tube ,  Thermal-hydraulic performance ,  Numerical simulation