Master's Thesis Proposal

 

Joy Metzler

(Advisor: Professor Juergen Rauleder)

"A CFD Analysis of the Molecular Kinetics in a Supercritical CO2 Circuit Breaker"

Tuesday, July 18

9:00 a.m. - 10:00 a.m.

Weber 200

Abstract

In this work, the behavior of supercritical carbon dioxide (SC CO2) at high pressures is investigated in regards to arc quenching capabilities. SC CO2 is a favorable replacement for the current method of SF6, which produces toxic byproducts. SF6 contributes heavily to the global warming crisis, and it is paramount to find a more environmentally conscious alternative. One possibility is SC CO2, which has a comparable dielectric strength to SF6 and shows promise in arc quenching applications; however, the behavior of SC CO2 is not as well researched as that of SF6, leading to a critical gap in knowledge needed to implement this change. To bridge this gap, a preliminary investigation of SC CO2 is done using the simulation program Charge Plus, developed by Electro-Magnetic Applications Inc. (EMA). Charge Plus is a Particle-In-Cell solver that, rather than using fluid properties, instead utilizes reaction probabilities to track macroparticles representing the flow of species in the simulation. The over-arching question this work seeks to answer is whether restrike will occur after the arc is quenched. This can be a combination of a few factors within the nozzle, to include temperature gradients, electric fields, and most importantly, electron avalanche. Some secondary questions that could be addressed after the main objective are the total power of the arc and the temperature of neutral species after microseconds, which can be useful to inform and validate with other computational solvers.

In this work, the behavior of supercritical carbon dioxide (SC CO2) at high pressures is investigated in regards to arc quenching capabilities. SC CO2 is a favorable replacement for the current method of SF6, which produces toxic byproducts. SF6 contributes heavily to the global warming crisis, and it is paramount to find a more environmentally conscious alternative. One possibility is SC CO2, which has a comparable dielectric strength to SF6 and shows promise in arc quenching applications; however, the behavior of SC CO2 is not as well researched as that of SF6, leading to a critical gap in knowledge needed to implement this change. To bridge this gap, a preliminary investigation of SC CO2 is done using the simulation program Charge Plus, developed by Electro-Magnetic Applications Inc. (EMA). Charge Plus is a Particle-In-Cell solver that, rather than using fluid properties, instead utilizes reaction probabilities to track macroparticles representing the flow of species in the simulation. The over-arching question this work seeks to answer is whether restrike will occur after the arc is quenched. This can be a combination of a few factors within the nozzle, to include temperature gradients, electric fields, and most importantly, electron avalanche. Some secondary questions that could be addressed after the main objective are the total power of the arc and the temperature of neutral species after microseconds, which can be useful to inform and validate with other computational solvers.

Committee

· Prof. Juergen Rauleder – School of Aerospace Engineering (advisor)

· Prof. Lucas Graber – School of Electrical and Computer Engineering

· Prof. Joseph Oefelein – School of Aerospace Engineering