Numerical Analysis of Heat Transfer and Fluid Characteristics in Long Distance HTS Cable

Abstract

Abstract Japanese national project, called “Materials & Power applications of Coated Conductors (M-PACC)”, started in FY2008. In this project, high temperature superconducting (HTS) cable using REBCO tapes has been developing. These HTS cables are expected as a compact size with large capacity and low loss power transmission. In the future, it is supposed that these cables will be installed in power grid for replacing existing power cables. Under the operating HTS cable in the power grid, it is necessary that the REBCO tapes in the long distance cable are kept cooling at low temperature stably and efficiently by liquid nitrogen (LN2). In this paper, the flow characteristic, such as pressure drop of LN2 flowing in the long distance HTS cable, and the heat transfer characteristic against heat generation, such as AC loss, and heat leak from cryostat-pipes were analytically estimated with varying the volumetric flow and the diameter of outer pipe wall which are parameters easy to control in cable system design. As a result, it was confirmed that the volumetric flow increasing is affective to extending the maximum distance which can be transmitted but it required increasing discharge pressure too. This increasing discharge pressure can be restricted without affecting the longitudinal distribution of the HTS temperature by expanding of the diameter of outer pipe wall.