LN2 circulation in cryopipes of superconducting power transmission line

作者：Sasaki A; Ivanov Yu; Yamaguchi S^*

来源：Cryogenics, 2011, 51(9): 471-476.

DOI：10.1016/j.cryogenics.2011.05.002

• Superconducting power transmission line
• Superconducting cable
• High temperature superconductor
• Liquid nitrogen
• Bellows pipe
• Pressure drop
• Computational fluid dynamics
• k-epsilon turbulence model

We propose and consider the application of superconducting power transmission lines (SC PTs) using high temperature superconductors (HTSs) for further reduction of the electricity losses. To keep HIS cable at low temperature it is usual to use liquid nitrogen (LN2). Straight and bellows pipes used in SC PT have different hydraulic friction factors due to differences in the shape of the wall surfaces. Moreover, the decentering of the HIS cable, which is unfixed at the center of the pipeline, also influences the LN2 flow. In the case of long SC PTs, high power must be expended to overcome hydraulic friction. There are two methods to evaluate pressure losses. One is based on empirical formulae and another is based on the algorithms of computational fluid dynamics (CFD). Empirical formulae can estimate pressure losses for long pipes, but the decentering of the cable is not considered. CFD computations describe flow behavior taking into account cable position inside the pipeline, though there is a limit to computable length due to the dependence on the number of mesh points and computation capacity. In this paper, circulation losses and pump power are estimated in straight and bellows pipes forming circulation channels by both methods. For a 40 mm diameter cable in an 80 mm diameter pipe, with the bellows pipe segments covering 2% of the length, and a heat loss of 1 W/m, the required flow rate and pump power for a circulation of 10 km are approximately 19 L/min and 10 W, respectively.

• 出版日期2011-9