A SHORT INTRODUCTION TO TWO-PHASE FLOWS Industrial occurrence and flow regimes Herv´ e Lemonnier DM2S/STFM/LIEFT, CEA/Grenoble, 38054 Grenoble Cedex 9 T´ el. 04 38 78 45 40 herve.lemonnier@cea.fr , herve.lemonnier.sci.free.fr/TPF/TPF.htm ECP, 2011-2012
CLASSES CONTENTS (1/2) • Introduction: CEA/Grenoble, scientific information • Two-phase flow systems in industry and nature • Flow regime • Measuring techniques, composition ( α ) • Simple models for void fraction prediction Industrial occurrence and flow regimes 1/61
CLASSES CONTENTS (2/2) • Balance equations • 1D models, pipe flow • Pressure drop and friction • Heat transfer mechanisms in boiling • Condensation of pure vapor • Critical flow phenomenon Recommended textbook: Delhaye (2008) Industrial occurrence and flow regimes 2/61
THERMAL-HYDRAULICS • Study of simultaneous flow and heat transfer, in French, thermohydraulique • Phase: state of matter characterized by definite thermodynamic properties • Two-phase: mixture of two phases ( diphasique ) • Examples: air and water, oil and water (connate), water and steam, oil and natural gas (multiphase), polyphasique ). Industrial occurrence and flow regimes 3/61
CEA/GRENOBLE RESEARCH CENTER • CEA: Commissariat ` a l’Energie Atomique (15000 p) • CEA/Grenoble: originates in 1956, founded by Louis N´ eel (4000p/2300 CEA) • Heat transfer laboratories founded by Henri Mondin • Nuclear energy directorate (5000 p, DEN) • Department of nuclear technology (400 p, Cadarache, Grenoble, DTN) • Department of reactors studies (400 p, Cadarache, Grenoble, DER) • Labs of simulation in thermal-hydraulics (SSTH) • Labs of experimental studies in thermal-hydraulics (SE2T) • Thesis advising capabilities and referenced research groups for several Masters. Industrial occurrence and flow regimes 4/61
LABS OF SIMULATION AND EXPERIMENTS IN THERMAL-HYDRAULICS • Codes ( logiciels ) for safety studies, CATHARE. • 3D Codes for two-phase boiling flows (Neptune). • LES of single-phase flow and heat transfer (TRIO-U). • Dedicated studies : safety and optimization of NR of various generations II, III and IV, ship propulsion, cryogenic rocket engines. • Analytic studies on boiling flows and critical heat flux (DEBORA) • Thermal-hydraulic qualification of fuel bundles (OMEGA) • Instrumentation development for single-phase and two-phase flows: Can only be modeled a quantity which can be measured Applications → models and codes → experimental validation → instrumentation. Industrial occurrence and flow regimes 5/61
SCIENTIFIC KNOWLEDGE AND INFORMATION • How to solve a technical/scientic issue? • Textbooks, books, journal papers: Library?. • Scientific Societies: journals editing, conference organizations (proceedings, actes ). – La Soci´ et´ e fran¸ caise de l’´ energie nucl´ eaire – La Soci´ et´ e hydrotechnique de France – La Soci´ et´ e fran¸ caise de thermique – American nuclear society, thermal-hydraulics division (NURETH) • Do you speak English? ... Industrial occurrence and flow regimes 6/61
TWO-PHASE SYSTEMS IN INDUSTRY AND NATURE (1/4) • Nuclear engineering: sizing, safety, decontamination (cleaning up) – Loss of coolant accidents (LOCA- APRP ). – Severe accidents w/o vessel retention. – Decontamination by using foam. – Nuclear waste reprocessing. • Oil engineering, hot issue: two-phase production – Transport. – Pumping. – Metering. – Oil refining (Chem. Engng). • Oil engineering : safety – Safety of installations. – LPG storage tanks and fire (BLEVE). Industrial occurrence and flow regimes 7/61
TWO-PHASE SYSTEMS IN INDUSTRY AND NATURE (2/4) • Chemical engineering – Wastewater treatment (interfacial area and residence time). – Gas-liquid reactors (falling film, trickle bed, air-lift). – Mixing and separation. – Safety: homogeneous thermal runaway. • Automotive industry – Diesel fuel atomization. – Combustion in diesel engines. – Cavitation damage : power steering, fuel nozzles. • Heat exchangers – Condensers and evaporator/steam generator. – Boilers (critical heat flux, CHF), heaters. Industrial occurrence and flow regimes 8/61
TWO-PHASE SYSTEMS IN INDUSTRY AND NATURE (3/4) • Hydroelectricity and water distribution – Water resources management: transients of pipings. – Priming of siphons. • Space industry – Cryogenic fuel storage (Vinci). – Thermal control of rocket engines (combustion chamber and nozzle). – Water hammer and pressure surges. – Cavitation in turbo-pumps. Instability (lateral loading) and damage. Industrial occurrence and flow regimes 9/61
TWO-PHASE SYSTEMS IN INDUSTRY AND NATURE (4/4) • Meteorology – Storm formation, rain/hail, lightning. – Ocean and atmosphere exchanges, aerosols formation. • Volcanology – Critical flow of lava in wells. – Steam explosion. – Nu´ ees ardentes (Vesuvius, protection of Naples suburbs). • Nivology – Avalanches. – Snow maturation (three-phase / 2-component). Industrial occurrence and flow regimes 10/61
� NUCLEAR REACTORS, WATER COOLED � � � � � � � � � � � � � � • Sizing : � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � SG: heat transfer and pressure drop. � � � � SGTR: critical flow at the safety � � � � � � � � � valve. FSI: mechanical loading and vibrations. � � � � � � • Safety : � � � � � � � � � � � � � � � � � � � � � � � � LOCA, fuel cladding temperature, � � � reference scenario • Decontamination : � � � � � � � � � � � � vessel, SG, minimizings wastes: foam � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Industrial occurrence and flow regimes 11/61
NUCLEAR FUEL • Fuel pellet. • Rod ≈ 10 mm in diameter (first confine- ment barrier). • Fuel assembly 17 × 17. • Control rods. • Length ≈ 4 meters. • Reactor core ≈ 4 m in diameter. • Heat transfer: forced convection (7 m/s.) • Thermal power 3000 ÷ 5000 MW. Industrial occurrence and flow regimes 12/61
STEAM GENERATOR • Tube-type, separates primary and secondary circuits (second confining barrier). • ≈ 5000 tubes, diameter 50 mm, height 10 m. • Pressure: 155-70 bar. • 3 or 4 SG and flow loops. • Inverted U-Tubes. • Secondary : two-phase flow. • Issues : heat transfer and vibration damage. Industrial occurrence and flow regimes 13/61
THE N4 PWR: SOME FIGURES • Primary side pressure: 155 bar, T sat ≈ 355 o C. Thermal power: 4250 MW. – Mass flow rate: 4928,6 kg/s per SG (4) – Core inlet temperature: 292,2 o C – Core outlet temperature: 329,6 o C • Secondary side, SG vapor pressure : 72,3 bar – Vapor temperature: 288˚ C – Feed water temperature: 229,5 o C – Mass flow rate: 601,91 kg/s per SG (4) • Assess the thermal balance of reactor and SG Source: National Institute of Standards and Technology (NIST) ( http://webbook.nist.gov/chemistry/fluid/ ) Industrial occurrence and flow regimes 14/61
SOME BAD NEWS... The following (low pressure) statements are rather wrong: • The mass balance reads, Q 1 = Q 2 , since water is incompressible, at least weakly it is dilatable. • The enthalpy is, h = C P T . • For a liquid, C P ≈ C V , or h ≈ u . • Steam is a perfect gas. Industrial occurrence and flow regimes 15/61
WATER DENSITY AT 155 BAR 750 Linear approx. ρ L , NIST 740 730 720 Density (kg/m 3 ) 710 700 690 680 670 660 650 290 295 300 305 310 315 320 325 330 Temperature (°C) Industrial occurrence and flow regimes 16/61
MASS BALANCE OF THE PRIMARY CIRCUIT • Mass flow rate per loop (CL), M L ≈ 5023 kg/s • Inlet density: ρ L 1 (292 o C , 155 bar) = 742 , 41 kg/s. • Outlet density : ρ L 2 (330 o C , 155 bar) = 651 , 55 kg/s. Q 1 = M L Q 2 = M L = 6 , 77m 3 /s , = 7 , 71m 3 /s ρ 1 ρ 2 • Volumetric flow rates differ by 13%. • The volume of the primary circuit is 400 m 3 ... Industrial occurrence and flow regimes 17/61
WATER ENTHALPY AT 155 BAR 1550 Linear approx. h, NIST 1500 1450 Enthalpy (kJ/kg) 1400 1350 1300 1250 290 295 300 305 310 315 320 325 330 Temperature (°C) Industrial occurrence and flow regimes 18/61
PRIMARY SIDE HEAT BALANCE • Mass flow rate per loop (CL), M L ≈ 5023 kg/s. • Inlet enthalpy: h L 1 (292 o C , 155bar) = 1295 kJ/kg. • Outlet enthalpy: h L 2 (330 o C , 155 bar) = 1517 kJ/kg. P = M L ∆ h ≈ 5023 × 222 10 3 = 1115 MW • 4-loop reactor power: 4460 MW. • Linear approximation: h = C P T , C P (292 o C , 155bar) = 5 , 2827 kJ/kg/K. P = M L C P ∆ T ≈ 5023 × 201 10 3 = 1008 MW • Power differs by 10%. • Temperature drift: 31 o C/hour. Industrial occurrence and flow regimes 19/61
WATER ENTHALPY & INTERNAL ENERGY AT 155 BAR 7 1550 C P , NIST C V , NIST u, NIST h, NIST 1500 6 Enthalpy, Internal energy (kg/m 3 ) Heat capacity (kJ/kg/K) 1450 5 1400 4 1350 3 1300 2 1250 290 295 300 305 310 315 320 325 330 Temperature (°C) Industrial occurrence and flow regimes 20/61
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