75443 - Thermohydraulics of Two-Phase Systems M

Course contents

- Conservation equation for mass, energy and momentum of a multiphase system, entropy inequality and constitutive equations
- Hydrostatics with interfaces: surface tension and equilibrium conditions at the interface in the static case
- Dynamics with interfaces: equilibrium at the interface in dynamical conditions, single-fluid formulation of the conservation equations, surface instabilities
- Two-fluid model for two-phase systems: derivation of the equation system and its approximations
- Two-phase flows in ducts: classification of flows and maps of flow regimes, pressure losses in two-phase flow
- Properties and stability of a single-phase system: thermodynamic potentials, stable and metastable states, equations of state (ideal gas and van der Waals)
- Homogeneous nucleation: metastable states, equiliobrium and stability of a single bubble in superheated liquids and of a single droplet in supercooled vapors
- Heterogeneous nucleation: Hsu model for nucleate boiling, growth regimes of a bubble in a superheated liquid, boiling cycle
- Pool boiling: boiling regimes, mechanisms for nucleate boiling, critical heat flux, film boiling
- Convective boiling in ducts: onset of boiling, subcooled and saturated boiling, critical heat flux
- Condensation: external film condensation on a vertical wall and horizontal ducts, internal condensation in horizontal tubes
- Nuclear reactor plants (PWR and BWR): description and thermohydraulics

Readings/Bibliography

Termoidraulica dei flussi bifase, S. Manservisi e R. Scardovelli, Progetto Leonardo, Esculapio (2012)

Other books:
- Liquid-vapor phase-change phenomena, V.P. Carey, Series in Chemical and Mechanical Engineering, Taylor and Francis(1992, 2007)
- Convective boiling and condensation, J.G. Collier and J.R. Thome, Oxford Engineering Science (1994)
- Direct numerical simulations of gas-liquid multiphase flows, G. Tryggvason, R. Scardovelli and S. Zaleski, Cambridge University Press (2011)

Teaching methods

The lectures are integrated by exercises on the blackboard and include the use of opensource numerical libraries and codes for two-phase flow
(https://github.com/VOFTracking/Vofi and http://basilisk.fr)

Assessment methods

A final written test with two exercises on pressure drops and heat transfer coefficient in two-phase systems, followed by an oral examination on the topics discussed in the course

Teaching tools

Projector and PC

Office hours

See the website of Ruben Scardovelli