Dipartimento Tecnologie Energetiche e Fonti Rinnovabili

Recent research activities

Recent research activities of Dr. Gian Piero Celata

  • Flow boiling heat transfer in microscale
  • Flow boiling heat transfer in microgravity
  • Heat transfer in nanofluids
  • Refrigeration systems for domestic and industrial applications, using refrigerants and CO2
  • Heat pipes for space applications
  • Heat pipes for solar cooling applications
  • Steam/water two-phase critical flow through safety devices
  • 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 components.
  • 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 refrigerant.
  • 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.