Cacuci, D. G.

Onea, Alexandru

Wörner, Martin

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Forschungszentrum Karlsruhein der Helmholtz-GemeinschaftDevelopment of a computer code for direct numerical simulation of mass transfer phenomena in two-phase flowsA. Onea*, M. Wörner* and D.G. Cacuci*** Forschungszentrum Karlsruhe, Institute for Reactor Safety** University of Karlsruhe, Institute for Nuclear Technology and Reactor SafetyJahrestagung Kerntechnik, Aachen16.-18.05.20062• Introduction• Extension of TURBIT-VoF computer code for the numerical simulation of mass transfer with/without first order chemical reaction in two-fluid flows• Validation of the diffusive and source terms• Influence of the unit cell length on the mass transfer process with/without chemical reaction• ConclusionsContents3• U(VI) extraction in TBP from HNO3 solutions in a micro-channel within the PUREX process (increased extraction efficiency, reduced amount of waste solutions, increased selectivity)1• Heat/mass transfer in two-fluid flows within mini/micro devices2– high heat/mass transfer rates due to high interfacial area per unit volume– mini/micro devices can operate under more stable conditions and use small amounts of chemicals (increased safety, isothermal flow)– well defined flow patterns1. H. Hotokezaka, M. Tokeshi, M. Harada, T. Kitamori, Y. Ikeda – Progress in Nuclear Energy 47, 439-447, 20052. V. Hessel, S. Hardt, H. Löwe – Chemical Micro Process Engineering, 2004Micro Bubble ColumnMonolithic Catalyst ReactorIntroduction4• Numerical code developed for simulation of laminar and turbulent flows in one-phase and two-phase flows in plane channels• Time-dependent conservation equations for mass, momentum and energy of two incompressible, immiscible fluids • Volume-of-Fluid technique for interface tracking • Transport equation for the liquid volumetric fraction• Periodic boundary conditions in flow directionComputer code TURBIT - VoF5Governing equations• Species conservation equation: • Fick‘s law: • Interfacial constitutive equation:• Interfacial local equilibrium instantaneously established (Henry‘s law):• Concentration field is transformed to ensure continuity k k k k kcc r , k 1,2t       v jD c    j1 2   j n j n12c , phase1cH c , phase 2  12cHc12c concentration of species in the liquidc concentration of species in the gas  61D2DJ. Crank – The Mathematics of diffusion, 1994D. Bothe, M. Koebe, K. Wielage, J. Prüss, H.-J. Warnecke  – In Bubbly flows. Analysis, modelling and calculation – M.Sommerfeld, ed., 159-174, 2004H = 5 H = 0.5H = 5 H = 0.5Validation of the diffusive term Line ALine BXYZFluid 2Fluid 1xyzFluid 2Fluid 1C  = 10C  = 00Line A7DiffusionConvectionHomogeneous CRMass transfer with first order homogeneous and heterogeneous reaction in single phase flowk = 0.5DiffusionConvectionHeterogeneous CRk = 50k = 0.5A. Apelblat – Chemical Engineering Science 19, 19 – 37 (1980)U 0c = c 0YXc = c 0cD  = k cyU0c = 0YXc = c 0Validation of the source term8Influence of unit cell length LUC on hydrodynamicsLUC [mm] Grid UB [m/s] UL [m/s] a [1/m]A 2.00 48x48x48 0.0964 0.0319 1168.8B 2.75 48x66x48 0.0964 0.0345 1476.4C 3.50 48x84x48 0.0969 0.0349 1770.6ABCM. Wörner, B.E. Ghidersa, A.F.Shahab – Proceedings of the 5th ICMF, 2004T.C.Thulasidas, M.A. Abraham, R.L. Cerro – Chemical Engineering Science 50, 183-199, 1995H = 0.03DG = 62.24 x 10-6 m2 / sDL = 19.16 x 10-6 m2 / skHet CR = 1500 s-1kHom CR = 50 m / sReB ~ 10Sc ~ 0.89Influence of LUC on mass transfer with and without chemical reactionNo chemical reaction Homogeneous reaction Heterogeneous reaction10Conclusions• Implementation of the diffusive term has been successfully validated against 1D and 2D analytical solutions  • Implementation of the source term has been successfully validated against analytical solutions of mass transfer with homogeneous and heterogeneous chemical reaction in single phase flows• Short unit cells are found more efficient than long unit cells for pure mass transfer and mass transfer accompanied by homogeneous chemical reaction, while long unit cells tend to be more efficient for mass transfer with chemical reaction at the wallFurther stepNumerical simulation of U(VI) transfer from HNO3 solutions into TBP solution

Development of a computer code for direct numerical simulation of mass transfer phenomena in two-phase flows

https://publikationen.bibliothek.kit.edu/240064679/150932200

Development of a computer code for direct numerical simulation of mass transfer phenomena in two-phase flows

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