Investigations on thermo physical properties of Supercritical Nitrogen to be used in HTS cables

Abstract

The demand for electrical power is a prerequisite for overall growth of Indian economy. Electrical power involving minimum losses would be a boon in serving nation's interest. However, the conventional power transmission cables system results in high transmission power wastage in the form of heat because any metallic electrical conductor having electrical resistance, when carries current, will generate Joule heat which is ultimately a loss in the supply power. High Temperature Superconductor (HTS) cables can transmit electricity with minimum electrical losses as these conductors exhibits minimum electrical resistance. Hence no resistance means no Joule heat generation and therefore it results in efficient power transmission.

However, maintaining the cryogenic temperature in HTS cables is still a challenge and desires attention due to the complexity involved in estimation such as hydraulic behaviors like pressure drop, friction factor, pumping power and thermal behaviors like thermal conductivity, specific heat under several operating conditions with optimized method.  To overcome such challenges, a novel method of cooling of HTS cable with Supercritical Nitrogen (SCN) (critical pressure of 33.958bar and a critical temperature of 126.19K) is recommended compared to liquid nitrogen (LN2). As the scientists and research scholars working on the development of superconductors with higher critical temperature, there is a need for the development of appropriate coolant to cool such futuristic HTS cables. The thermo hydraulic properties of SCN are studied comprehensively and found that there is a drastic variation in these properties.