14 / 2024-03-24 09:37:38

Advancements in Modeling Chemically Non-Equilibrium Decaying Arc Plasmas in C-F-O Gas Mixtures

SF6 alternative gas,Arc,Circuit breaker,local thermal Non-Equilibrium

Gas circuit breakers (GCBs) use molecular gas to extinguish arc plasma that forms between electrodes during high-current interruption processes. The arc plasma is extinguished due to its rapid decay around current zero. To develop more compact and reliable circuit breakers, it is important to have a comprehensive understanding and prediction of arc interruption phenomena. Numerical thermofluid simulation has emerged as a valuable tool for achieving this objective. While typical simulation models assume local thermodynamic equilibrium (LTE) conditions in arc plasmas, arc plasmas in molecular gas flows can exist in a state of chemical non-equilibrium due to rapid state changes and finite reaction rates. It is important to acknowledge the complexity of plasma behavior and the potential for non-equilibrium conditions. Previously, the authors developed two-dimensional (2D) models to simulate decaying SF₆ arc plasmas[1-5], including full chemically non-equilibrium models and two-temperature (2T) chemically non-equilibrium models, both of which predicted both thermal and chemical non-equilibrium states. However, SF₆ is a potent greenhouse gas with a high global warming potential. Therefore, it is imperative to research alternatives. Recently, more environmentally friendly options such as CO₂-based gas mixtures like CO₂/C₄F₇N and CO₂/O₂/C₄F₇N have emerged as alternatives. However, the availability of C₄F₇N remains a concern, which necessitates further research into SF₆ alternatives.



This paper presents a chemically non-equilibrium model for decaying arc plasmas in gas mixtures consisting of C-F-O. The model examines the behavior of CO₂ gas-blast arcs with PTFE ablated vapor and incorporates a total of 134 reactions, comprising of 67 forward reactions and their corresponding reverse reactions. The simulation model indicates differences from LTE models, highlighting the importance of accounting for chemical non-equilibrium in arc plasma simulations.



References

 

1. Y. Tanaka, K.Suzuki, IEEE Trans. Power Delivery, 28, Issue 4, (2013)2623-2629


2. Y. Tanaka, K.Suzuki, T.Iijima, T.Shinkai, Proc. 2nd Int. Conf. Electric Power Equip.ICEPE2013, (2013), Matsue, Japan


3. Y. Tanaka, K. Suzuki, ICEPE-ST2015,(2015) GO-181, Pusan,S.Korea


4. Y. Tanaka, K.Suzuki, Proc. 20th Int. Conf. Gas Discharges and Their Appl. GD2014 (2014), A34, 179-182


5. Y. Tanaka, K. Suzuki, T. Iijima, Proc. 21th Int. Conf. Gas Discharges and their Applications, (2016),  A15, 57-60, Nagoya, Japan