Recent research activities of Dr. Gian Piero Celata
- Two-phase critical flow in pipes and nozzle using water as a
process fluid. Experimental determination of critical thermohydraulic
parameters (critical mass flux and pressure) and theoretical
prediction. Two-phase jets thermodynamic analysis using x-rays.
Problems connected with the loss of coolant accidents scenario in
nuclear reactor safety.
- Critical heat flux under transient conditions: flow, pressure and
power transients. Simple and complex transients. Experimental
determination of the critical heat flux in long channels. Computer code
development for the analysis of the critical heat flux under transient
conditions. Flow pattern analysis using optical probes.
- Direct contact condensation of steam on subcooled water.
Experiments of direct contact condensation of saturated and superheated
steam on: a) horizontal flowing water - pool and rectangular channel-;
b) liquid jets; c) liquid sprays (uniform size droplets). Modelling of
the steam/water direct contact condensation.
- Flooding in air/water countercurrent flow in pipes with and
without obstructions. Experiments for flooding characterization in
vertical and inclined circular ducts of different length and diameters,
using air/water and air/water-glycerol. Effect on flooding of the
presence of obstructions in the middle of the channel. High speed
movies of the phase interface (waves). Analysis of the hysteresis
effect in the flooding phenomenon. Modelling of the flooding in
vertical and inclined pipes, with and without obstructions.
- Thermomechanical behaviour of plasma-facing components for fusion
reactors. Analysis of the thermal cycling behaviour of fusion reactors
- Onset of subcooled flow boiling of well wetting fluids and water.
Experimental investigation and theoretical modeling of the hysteresis
effect in the boiling incipience of refrigerants in pipes. Experimental
determination of the incipience boiling heat flux in water at high
liquid velocity and subcooling.
- Heat transfer and critical heat flux of refrigerant binary
mixtures in long pipes. Experimental determination of the heat transfer
characteristics, up to the critical heat flux, of mixtures of different
compositions, and comparison with the ideal behaviour derivable
from the heat transfer performances of the pure fluids.
- Direct contact boiling of immiscible liquids (water and freon).
Experimental investigation of the vaporization rate of saturated R 144
jets injected into a column of stagnant water. High speed movies of the
freon boiling in water.
- Burnout at high heat fluxes. Experimental determination of the
subcooled flow boiling critical heat flux in small diameter channels,
using water as a process fluid, at high liquid velocity and subcooling
(cooling of plasma facing components in fusion reactors).
Thermohydraulic characterization (flow rate, pressure and subcooling)
of the burnout under conditions relevant for the thermal-hydraulic
design of the divertor. Modeling of the critical heat flux in subcooled
flow boiling. Use of turbulence promoters for the enhancement of the
critical heat flux (helically coiled wires, ENEA patent).
- Heat Transfer in solar receivers.
- Bubble rising velocity in one- and two-component systems.
- High temperature air/water direct contact heat transfer in pipes.
- Heat transfer characteristics of binary and thernary mixtures of
refrigerants: the new generation of the ozone friendly
- Compact heat exchangers (evaporators and condensers) analysis
using new generation refrigerants.
- Spray cooling of high temperature surfaces.
- Heat transfer and fluid flow in single-phase.
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Current Research Activities