Sherif H. Abdulla, Xin Liu, Mark H. Anderson, R. Bonazza, M. L. Corradini - University of Wisconsin University of Wisconsin - - Madison Madison 1. Research Objective: 2. Previous Investigations: An experimental facility has been designed and constructed at UW-Madison. It consists mainly of three components, namely, 1. Liquid Metal Reservoir 2. Test Section 3. Condenser The previous investigations can generally be divided into two main categories: I. Water/Light, low boiling point pair: Sideman & Taitel (1964), Sideman & Gat (1966), Blair et al. (1976), Smith et al.(1982), others II. Liquid metal/Water pair: El-Boher et al. (1988), CRIEPI (1995-97), Boungiorno et al. (2000) The main objective for most of the previous investigations was to find the overall volumetric heat transfer coefficient for the exchanger. One concept being considered for steam generation in innovative nuclear reactor applications, involves water coming into direct contact with a circulating molten metal. The vigorous agitation of the two fluids, the direct liquid-liquid contact and the consequent large interfacial area can give rise to large heat transfer coefficients and rapid steam generation. For an optimum design of such direct contact heat exchange and vaporization systems, detailed knowledge is necessary of the various flow regimes, interfacial transport phenomena, heat transfer and operational stability. Scope of the Current Study 1. Fuel-Coolant interactions envelope 2. Flow regime boundaries 3. Void fraction 4. Different zone lengths 5. Heat transfer coefficients 3. Experimental Facility: Semi Cylindrical Radiant Heaters 16,400 W, 980 °C max 6 Tubular Heaters 15,000W total, 650 °C max Surge Level 0.03 m 3 Level Melt/Chill Reservoir Vac/Press. Port Molten Metal Transport Line 45.75cm × 184cm × 10.2 cm Test Section 92 cm Instrument Ports Vac/Press. Port 184 cm Test Section • Overall Pressure : 1-10 bar • Liquid Metal Temperature : 400-500 °C • Water Inlet Temperature : T sat –10 °C • Water Flow Rate : 1-10 g/s Features High Energy X-ray Movable Head 1000 Rads/min 104 Pulsing Rate Features High Energy X-ray Movable Head 1000 Rads/min 104 Pulsing Rate Features 256 x 256 resolution 16μm x 16μm pixels 8-bit A/D conversion 104 frames/second Features 256 x 256 resolution 16μm x 16μm pixels 8-bit A/D conversion 104 frames/second Digital Camera X-Ray Head ~ 13 cm ~ 5 cm Z 4 Z 3 Z 1 Z 2 Screen L Lsub Lsat Lsup Liquid Metal Steam Reservoir Imaging System Test Section X- ray Re s er voir Pump T o Condens er Liquid Metal Water Immersion Heaters T/C Probe 4. Test Conditions: 5. Results: • Production Time : - Analysis of the 500 images taken for the injector tip during one experiment along with the framing rate gives the bubble production time. Test section CCD Len s Image Intensifier Len s X-ray head PC Lead shielding X-ray screen Mirror Lead Shielding • Rise Velocity: Analysis of the 500 images taken for each imaging zone during one experiment along with the frame rate gives the bubble rise velocity. Injector Water Water ∆τ ∆y 1 ∆y 2 Water Reservoir Cover Clamshell Heaters Insulation - Time it takes to build a bubble around the injector before its departure to the pool. -F buoyancy < F surface tension Injector Frame Number Increases ( 1!500) Water f 42 f 43 f 44 f 45 f 46 f 47 f 48 f 49 • Void Volume: • Volumetric Heat Transfer Coefficient: ( ) m , l inlet exit v T V i i m U ∆ - =          - - - = ∆ exit lm inlet lm inlet exit T T T T ln T T m , l T i inlet = f (T inlet ,P inlet ) i exit = f (T exit ,P exit ) Subcooled water inlet Superheated steam exit f 1 f 2 f 3 f 4 f 5 f 6 f 7 f 8 13 cm d in = 2 mm 15 cm Test Conditions: Single injection T inj, water ≅ 100 °C T steam,exit ≅ 380 °C T LM ≅ 500 °C flow rate ≅ 1 g/s 0 0.2 0.4 0.6 0.8 1 1.2 0 250 500 750 1000 1250 1500 Time [Sec] Flow Rate [g/s] 0 100 200 300 400 500 600 Temperature [c] LM Temp Water Flow Rate Tsteam Twater X-ray imaging window X-ray imaging window ≅ 5 sec. d injector ≅ 2 mm 1.42 3 0.93 2 0.59 1 V rise [m/s] Zone " An experimental facility has been designed and used successfully to measure the void fraction at different heights within the liquid metal pool. " Bubble production time and bubble rise velocity have been estimated from the X-ray images taken for the liquid metal/water pool " The test facility provides the means to estimate the void volume and void interfacial area within the pool. " The overall volumetric heat transfer coefficient based on the liquid metal level swell could be estimated " The local heat transfer coefficient at different pool heights will be estimated using the following procedure: 6. Summary and Future Plans: 1. Evaluate the bubble production time [x-ray image analysis] 3. Calculate the specific volume: w bubble z m Vol v = 1 4. Calculate the quality: fg f z v v v x - = 1 5. Calculate the enthalpy: fg f z i x i i + = 1 6. Calculate local HTC: ( ) ( ) time rise T T A i i time production m h w lm erfacial int f z w z × - × - × × = 1 1  time production m m w w × =  2. Calculate the injected water mass: Dae H. Cho, R. J. Page, D. Hurtault - Argonne Argonne National Laboratory National Laboratory Direct Contact Heat Exchange Interfacial Phenomena for Liquid Metal Reactors Part II: Void Fraction 0 100 200 300 400 500 600 0 10 20 30 40 50 60 Distance from Injector [cm] Volume [ cm 3 ] Image processing, 1bar Ellipsoid model, 1bar Ellipsoid model, 4bar Image processing, 4bar Avg. over 100 f, 1bar Avg. over 100 f, 4bar = 1 g/s m  P = 4 bar P = 1 bar Temp. Controller Condenser [Suppression tank] Steam Inlet X-ray system control unit Data Transfer Line