Influence of corrugation topology on thermohydraulic performance of cold dielectric counter cooled high temperature superconducting cable

Abstract

Fluid flow, pressure drop and heat transfer across the long length cold dielectric counter cooled High Temperature Superconducting (HTS) cables are significantly influenced by the different corrugation (rectangular, circular and triangular) topologies. Thus, in this present work, thermal and hydraulic characteristics of turbulent LN2 flow in counter cooled HTS cable with various corrugation topologies are computationally investigated. The 2-D axisymmetric model of HTS cable with counter flow cooling system is considered by changing the corrugation shapes for Reynolds number ranging from 3.0 × 104 to 6.0 × 104. Heat flux from ambient temperature on outer corrugated pipe and heat generation from A.C. losses in the HTS tapes are also considered in the present simulations. In addition, distribution of the velocity, temperature and turbulent kinetic energy (TKE) of liquid nitrogen (LN2) in the HTS cable with various corrugations are estimated using computational fluid dynamics (CFD) technique. Finite volume method is adapted to solve the governing equations (continuity, momentum and energy) using Semi-Implicit Pressure Linked Equations (SIMPLE) scheme with k−ε turbulence model and enhanced wall treatment. The results reveal that the corrugation topologies (rectangular, circular and triangular) have significant effect on heat transfer and pressure drop. The corrugated pipes with different topologies exhibit different friction factors due to the variations in the contact of wall surfaces with the LN2. Moreover, the calculated friction factors for all the three corrugation topologies are compared with the experimental results available in the literature. Further, the results of temperature difference between outlet and inlet temperatures of LN2 are validated with the available experimental measurements. Finally, it was concluded that the effect of heat flux and AC Losses on cooling capacity and heat transfer is found to be significant as compared that on friction factor and pumping power.