CFD Simulation and Design of a New Supercritical CO2 Circuit Breaker Contact and Nozzle System

High-voltage alternating current SF
6
circuit breakers are used as vital components for power grid control and protection. Our previous work has shown the outstanding dielectric strength of Supercritical (SC) CO
2
and suggests that SC CO
2
could be a potential arc quenching medium for high-voltage circuit breakers (HVCB) due to its good thermal conductivity and reduced mean free path. However, one foreseeable challenge of the utilization of SC CO
2
as an arc quenching medium in HVCBs is its limited compressibility and its high critical pressure and temperature to maintain its supercritical phase. Reaching the compressibility limit must be avoided since it can lead to shockwaves, which can damage internal circuit breaker hardware. In this paper, the development of a simplified computational fluid dynamics (CFD) model of a new SC CO
2
circuit breaker during an arc-quenching process is discussed. Results indicate that the SC CO
2
does not undergo a phase change despite being subject to an ionizing temperature, and that a converging nozzle is sufficient for flow acceleration.