Feasibility Analysis on Cryogenic Properties of Supercritical Nitrogen to be used in the Cooling of Hg-Based High Temperature Superconductors for Electric Aircraft Propulsion

Abstract

Electrified Aircraft Propulsion (EAP) and Advanced Hybrid Electric Aircrafts (AHEA) like NASA NX-3, SUGAR, NASA X-57 and STARC ABL are going to be the future of avionics as they have potential to improve fuel economy, emissions and noise levels. The agencies have suggested using superconducting cables for the electric transmission to reduce heat losses. The limit of critical current has reached 134 K where Hg- based ceramic materials are available that can superconduct at this temperature range. In order to retain the superconductivity, the cables have to be cooled below its critical temperature. Liquid nitrogen (LN2) boils of at 77 K which further leads to multiphase heat transfer challenges. An attempt has been made in the present work to overcome such challenges and a novel concept of using Supercritical Nitrogen (SCN), having critical temperature 126.19K and pressure as 3.3958MPa (consist single phase), as a cryogen for the cooling of Hg-Based Superconductors, has been introduced. Drastic variations have been found for thermophysical properties of SCN near the critical point. It has been concluded that few temperature and pressure ranges are suitable if one wants to incorporate SCN as cryogen for Hg-based superconductors.