ML21098A129
| ML21098A129 | |
| Person / Time | |
|---|---|
| Issue date: | 04/06/2021 |
| From: | Fierro A, Hopkins M, Lafleur C, Gabe Taylor Office of Nuclear Regulatory Research, Sandia, Univ of New Mexico |
| To: | |
| Kenneth Hamburger | |
| Shared Package | |
| ML21098A124 | List: |
| References | |
| Download: ML21098A129 (16) | |
Text
HEAF Modeling with Sierra M. Hopkins 1, A. Fierro 2, C. LaFleur 1, A. Glover 1, G. Taylor 3 1 Sandia National Laboratories 2 University of New Mexico 3 National Regulatory Commission Sandia National Laboratories is a multimission laboratory managed and operated by National Technology &
Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S.
Department of Energys National Nuclear Security Administration under contract DE-NA0003525. SAND2021-4079 PE
2 Sierra Plasma Arc Modeling The conduction of current through the gas (arc) is the source of gas heating, melting and vaporization of metal, and radiation.
The NIST simulation software Fire Dynamics Simulator (FDS) has expertise in gas heating and transport mechanisms but does not have a capability for accurate modeling of the arc physics.
Sandia National Laboratories (SNL) has extensive capability and expertise in simulating arc physics. Scales for arc physics are micron (and smaller) and require accurate modeling of charged particle transport to capture localized heating effects.
The current approach is to use a Sierra model for the arc and local gas transport, then transfer results to FDS for the full domain transport problem.
Arc domain (walls removed for viewing cabinet internals)
3 HEAF - a Complex Multi-scale Coupled Physics Problem Arc Physics (m scale)
Electrode Melting/Vaporization (mm scale)
Gas Heating (cm-to-m scale)
Radiation (m scale)
Feedback from different phenomena lead to a coupled physics problem
4 Arc Model Overview The Sierra model couples together hydrodynamics (Fuego), plasma physics (Aria), and radiation transport (Nalu).
It is possible to investigate differences in electrode materials, gas composition, gas optical thickness, and other parameters, depending on resource allocation.
The model currently assumes a DC plasma discharge (providing time-averaged heating rates).
Plasma Arc Model Electrode Heating Model Aria Solution Gas Transport Model Fuego Solution Radiation Transport Model Nalu Solution
5 Example Coupled Problem Gas region Mass Momentum Turbulent kinetic energy Energy Radiation (Nalu)
(provide plasma region temperature)
Electrodes (also calorimeters)
Energy Radiation Plasma (arc) region Potential Current density Charged species (provide gas region energy source term)
Entire domain
6 Open Box OBMV4 Nominal parameters:
- 6900 V L-L system voltage
- 14.3 kA
- 264 V L-N arc voltage
- 5 s duration Model Setup:
- Injection of 14.3 kA (electron current) from middle electrode.
- Middle and left electrode fixed at -264 V.
- Right electrode and walls held at ground.
7 Temperature Evolution (Al Mass Fraction = 0.3)
Location 1 Location 2 Location 3 Have not yet reached a steady-state temperature in the plasma volume.
Heating term from arc has stabilized.
Open Box - OBMV4 time (ms) 0 3
6 9
temperature (K) 2000 0
5000 1000 500 t = 5 ms
8 Probe location Temperature Rise Difference in Cu vs. Al This simulation does not yet include the Al combustion reaction
-- in the process of testing it.
Open Box - OBMV4 time (ms) 0 3
6 9
temperature (K) 0 2500 5000 t = 5 ms
9 Increasing Al mass fraction (0.01, 0.1, 0.3)
Probe location Influence of Al Mass Fraction Open Box - OBMV4 time (ms) 0 3
6 9
temperature (K) 0 2500 5000 t = 5 ms
10 Medium Voltage Switchgear Simulations - 2018 KEMA Test Focus on plasma region only Nominal parameters:
- 6900 V L-L system voltage
- 25.76 kA
- 246 V L-N arc voltage
- 2 s duration Model setup:
- Injection of 25.76 kA (electron current) from middle electrode to right electrode.
- Middle and left electrode fixed at -246 V.
- Other electrode and surfaces at ground.
No metal or combustion reaction included
11 Localized Heating Locations of gas heating due to arc (plasma) formation.
90% total power 50% total 10% total NRC 2018 KEMA Test
12 Evolution of gas temperature and heating source NRC 2018 KEMA Test
13 Current Activity Complete Al Oxidation Reaction
- Al + O2 AlO + O Continue definition of hand-off parameters for plasma arc source term to FDS model
- Power
- Radiation fraction
- Compare temperatures between FDS and Sierra Develop other geometries and operating conditions for ZOI calculations
14 Backup Slides Follow
15 Gas dynamics
()
+ T = +
(energy)
+ = 0 (momentum)
+ + =
(continuity)
=
=
=
(Heating/Coupling between equations)
Plasma arc (drift-diffusion approximation)
+ =
(charged species continuity)
= +/-()
(flux term) 2=
)
(
=
(electrostatic voltage and electric field)
Radiation transport (transport)
(boundaries)
(energy source) 1-term turbulence model equation Species transport (Al/Cu)
Fully-coupled Model Equations
16 Metal Vapor Fraction
- We showed 30% but we include other fractions
- Literature shows that our guesses are reasonable
- There are no measurements of droplet vs. vapor distribution of electrode material