Multiphase Lab
Refrigerant fluids
This field of study analyzes heat transfer and fluid dynamic characteristics during flow boiling and convective condensation of new refrigerants inside both standard and specially configured tubes (microfin tubes, herringbone tubes, multiport mini-channels)
Multiphase Fluid-Dynamics
This research topic includes fluid dynamic studies of adiabatic two-phase and three-phase flows aimed at improving accuracy of pressure drop models for oil & gas transportation (gas-liquid, liquid-liquid, and gas-liquid-liquid flows) and efficiency of gas cleaners equipments (gas-solid and gas-liquid-solid flows). Phase distribution and flow regime transitions are also deeply investigated
Drop analysis
Analyses of drop-surface interaction and evaporative dropwise cooling for both sessile and impinging drops.
The interactions between drops and solid surfaces or gas/liquid interfaces are analyzed from a thermal and mechanical standpoint, evaluating equilibrium configurations after drop deposition or impacts.
As for solid surfaces, experimental analyses are conducted to evaluate the drop geometric characteristics (shape, contact angle) and thermal parameters during evaporation (times, power, fluxes).
As for gas/liquid interfaces, Computational Fluid Dynamics (CFD) studies are carried on to characterize the evolution of the crater and crown caused by the drop impact.
Wettability analyses, studies of surface covering capability of drops or sprays and heat transfer analysis are applicable to improve printing processes, electronic devices cooling or spray treatment of agricultural fields.
Optical Heat Exchange Measurement Laboratory (MOST)
The experimental activities concern the development and application of optical heat exchange measurement techniques. The available methods allow the non-invasive detection of thermal fields. In particular, holographic interferometry and digital speckle photography are respectively used to determine the distribution of temperature and the temperature gradient in transparent media, while thermography is applied to measure the surface temperature in both natural and forced convection. The joint analysis of the motion field through LDV allows a complete description of the convective heat exchange. In addition, the numerical simulation with commercial codes constitutes a support activity for experimentation.
The main application of the mentioned techniques concerns the analysis of the increase in heat exchange following the adoption of specially shaped surfaces, equipped, for example, with offset, louvered, perforated and corrugated fins or corrugations of different geometry. This forms the basis of the rational design of compact heat exchangers, since it affects both the size and the cost of construction, as well as the energy saving.
Location:
Politecnico di Milano - Department of Energy - campus Bovisa
via Lambruschini, 4A (building BL25 - BL25A)
20156 Milano
Contacts:
Alfonso Niro
phone number: +39 02 2399 3905
mail: alfonso.niro(at)polimi.it
Web: http://www.thermalab.polimi.it/laboratories/multiphaselab
http://www.tfdmultifase.polimi.it/
Staff:
- Alfonso Niro
- Luigi Colombo
- Manfredo Guilizzoni
- Andrea Lucchini