Subject 1. Introduction to Multiphase Flow.
Scope. Multiphase ﬂow notation. Flow patterns. Conservation of mass. Continuum equations for conservation of momentum. Averaging. Equations for conservation of energy.
Subject 2. Two-phase adiabatic flow.
Basic equations of two-phase flow. Homogeneous model. Separated flow model. Drift flux model. Empirical treatments. Extension to three-phase liquid-liquid-gas flows.
Case studies. Pressure loss evaluation in pipe flow and through enlargements, contractions, orifices, bends and valves.
Subject 3. Vapour-Liquid Systems.
Boiling heat transfer. Nucleation and bubble dynamics. Pool boiling. Critical Heat Flux. Convective boiling: flow regimes, onset of subcooled nucleate boiling, partial subcooled boiling, fully developed subcooled boiling, saturated forced convective boiling, dryout versus departure from nucleate boiling.
Case studies. Thermo-hydraulic design of Once-Through Boilers.
Condensation. Liquid formation and droplet growth. Film condensation on planar vertical and inclined surfaces, on horizontal and vertical tubes and tube bundles. Influence of the interfacial shear. Condensation within vertical and horizontal tubes. Drop-wise condensation.
Case studies. Thermo-hydraulic design of Steam Power Plant and Process Condensers.
Subject 4. Gas-Solid (Particle) Systems.
Classification of Gas-Solid Flows. Dynamics: gas-particle and particle-particle interactions, mass and momentum transport, convective heat transfer.
Case studies. Pneumatic conveying: flow regimes, classification of bulk solids, phase diagram, dilute versus dense phase conveying, saltation velocity, pressure drop in dilute and dense phase systems. Fluidized Beds: flow regimes, velocity and pressure, heat and mass transfer.
Subject 5. Liquid-Solid Systems.
Solidification and Melting. One-dimensional Stefan problem. Phase change with convection. Phase Change Materials for energy storage.
Case Studies. Freezing time of a liquid in a tube. Freezing in pipelines cooled by surrounding ambient air.
LABORATORY ACTIVITIES. Students will be involved in the experimental activities of the Multiphase Flow Laboratory at the Department of Energy, aiming at: major understanding of theoretical modelling through experimental validation; design and setup of suitable test sections; planning and execution of experimental runs, processing of empirical data. According to the availability of the facilities, attention will be turned to either liquid-liquid-gas adiabatic flows or forced convective boiling/condensation heat transfer.
SEMINARS. Specialists coming from both research and industrial contexts will present the most recent advancements in multiphase flow physics and technologies.
5 ECTS course for Nuclear Engineering. The contents are limited to Subjects 1 to 3.