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Corrosion in Liquid Metal MHD flow

Corrosion in Liquid Metal MHD flow. By S. Saeidi Contribution from: S. Smolentsev, S. Malang University of Los Angeles August, 2009. Outline. Introduction Motivation/Goals Problem Definition Mathematical model Numerical Code Test Results Conclusion and Future Investigation.

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Corrosion in Liquid Metal MHD flow

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  1. Corrosion in Liquid Metal MHD flow By S. Saeidi Contribution from: S. Smolentsev, S. Malang University of Los Angeles August, 2009

  2. Outline • Introduction • Motivation/Goals • Problem Definition • Mathematical model • Numerical Code • Test Results • Conclusion and Future Investigation

  3. Introduction • Liquid metal, such as PbLi has so many advantages using as heat transfer fluid • Corrosion behavior of ferritic steel exposed to PbLi is not well understood • Maintaining acceptable limits for material loss is an important goal in blanket development • For ferritic steel/PbLi, corrosion is controlled by convection, diffusion and dissolution at the solid-liquid interface • Mass, heat and momentum transfer are coupled • The main purpose is to develop a numerical code to access corrosion of ferritic steel in PbLi under either experimental or real blanket conditions

  4. Motivation/Goals • There are no commercial codes available for corrosion analysis under fusion blanket conditions • Experimental data are available on ferritic steel/PbLi corrosion, but no good interpretation exists • We need a code, which would help us to perform some initial corrosion analysis under blanket conditions • We want to help experimentalists to understand the data, and to understand the corrosion phenomenon itself • Use of code for benchmarking with more sophisticated software, which is planned to be developed in future (HIMAG)

  5. Problem Definition for Ferritic Steel/PbLi Corrosion/Deposition • Corrosion is a result of dissolution of wall material, which is then transported by the flow • Transport mechanism are convection and diffusion • Flow is either laminar or turbulent. MHD effects should be included • We consider only one component (Fe) diffusing into PbLi • We also consider deposition phenomenon, which occurs in the cold part of the loop • Heat, mass and momentum transfer are coupled. The mathematical model should include energy equation, flow equations (including MHD effects), and mass transfer equation • The boundary condition at the solid-liquid interface assumes saturation concentration at given wall temperature

  6. Mathematical Model: governing equations m=0 – plane geometry m=1 – pipe t, kt, Dt=0 – laminar t, kt, Dt>0 – turbulent Turbulence closures are used to calculate t, kt, Dt MHD effects are included through jxB, P/x, t, kt, Dt More equationsare used to introduce MHD effects • Flow • Heat Transfer: • Mass Transfer:

  7. Mathematical Model:Input Data Saturation concentration Csat of iron atoms in PbLi as function of temperature Mass diffusion coefficient plotted as a function of the wall temperature Borgstedt, H.U and Rohrig, H.D:1991, Journal of Nuclear Materials 181-197 • Saturation concentration equation expressed in mole fraction (percentage)

  8. Numerical Code • Velocity distribution can be calculated for both laminar and turbulent flow regimes for simple geometries (pipe, rectangular duct, parallel channel) with or without a magnetic field • Finite-difference computer code • Non-uniform meshes with clustering points near the walls • Implicit method for solving equations (Tri-diagonal solver)

  9. Test Results, 1 Plot of Nusselt number along x direction in Plane channel with parabolic velocity profile The comparisons have been made for a laminar flow

  10. Test results, 2 Temperature profile Concentration profile Flow Length: 2m Channel Width: 20cm Twall= 500 C Laminar flow= U=3 cm/s Cwall=0.01 Kg/m3

  11. Test Results, 3 Rate of mass transfer along the X direction: Plot of Sherwood number along the X direction: • Sh decreases along the x until the flow become fully developed

  12. Conclusion and Future Investigations • Initials steps towards a mathematical model and numerical code for modeling of corrosion/deposition processes have been performed • We will keep working on the code and use it to analyze the effect of the flow regime, MHD, flow geometry, inlet conditions, etc. on corrosion/deposition of ferritic steel in PbLi under either experimental or real blanket conditions • We will look for experimental data and run the code trying to reproduce the experimental data • In the future, the code will be used for benchmarking with more sophisticated software (HIMAG)

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