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Work description and objectives:  Heat transfer in forced convection inside rectangular channels is a very interesting matter for industry as it is encountered in critical heat transfer applications like gas-turbine blade cooling, and in devices largely used such as plate-fin compact heat exchangers. In designing these devices, high values of heat transfer area per unit volume are searched for; however, if this parameter is increased over a given value, thermal performances start worsening. In fact, the higher the surface-to-volume ratio the narrower the passages, so air velocity has to be lowered to maintain acceptable the pressure drops; however, narrow passages and low air velocities lead to laminar flows, that are characterized by a rather poor convective coefficient which eventually defeats completely the area increase benefits. To overcome this limit, heat transfer is enhanced by configuring surfaces with a large variety of fins, ribs and corrugated surfaces, which are an efficient and cost-effective solution. Two experimental research lines are carried out in parallel at the ThermALab, along with Computational Fluid Dynamics (CFD) simulations, on forced convection inside rectangular channels with walls structured with a variety of ribs configurations, concerning

• measurements of average heat transfer characteristics as well as of pressure drops;
• measurements of velocity and temperature gradient fields, and flow visualization as well by means of not intrusive optical techniques (BOS, PIV);

Both topics are subjects of MSc thesis. The activity must include a preliminary literature review, and experiments have to be carried out at the ThermALab laboratory, Department of Energy, Campus Bovisa.

Required skills:  Attitude towards experimental activity, and heat and mass transfer problems. LabView knowledge is a plus for local measurements.

Work description and objectives: Non Destructive Testing (NDT) methods are used every day as a fundamental quality control and maintenance tool in many industrial applications, from aerospace composites materials to electronic components, from pipelines to buildings. IR-thermography based NDT methods use the propagation of heat pseudo-waves as a mean to identify the presence and the geometry of internal defects by recording the surface temperature field of the specimen after, or during, a thermal stimulus. Research activity in the ThermALab is focused on low conductivity non-metallic samples. MSc thesis available topics are thermographic image treatment algorithms, curved and composite samples analysis, and FEM parametric models and simulations. The activity must include a preliminary literature review, and experiments have to be carried out at the ThermALab laboratory, Department of Energy, Campus Bovisa.

Required skills: Attitude towards experimental activity, and heat and mass transfer problems. Matlab knowledge. Any experience with COMSOL Multiphisics would be a plus.

Work description and objectives:  In recent years, solar protection systems are used and studied as a promising energy saving technology for buildings, both for cold and hot climates. Many solutions have already been proposed, and some of them are already adopted and show interesting results, especially in reducing the air conditioning power consumption during hot seasons. Standard measurements are defined to evaluate global radiometric characteristics of semi-transparent surfaces, however those standard are often incapable of describing new surfaces or complex interaction between various media. The ThermALab is equipped with a top-grade UV-Vis-NIR (solar range) spectrophotometer, and with TracePRO software, which is the standard in radiative heat transfer simulations. A second spectrophotometer operating within the medium and far IR has been just acquired and it will be operative in the next months. The latter spectrophotometer will allow to extend measurements of spectral reflectivity and emissivity to the whole IR range. The MSc thesis subject is the experimental and theoretical study of radiometric proprieties of innovative semi-transparent media, smart films and finishing; modelling simulations could be possibly carried out on the basis of experimental data. The activity must include a preliminary literature review, and experiments have to be carried out at the ThermALab laboratory, Department of Energy, Campus Bovisa.

Required skills:  Attitude towards experimental activity, good knowledge of radiative heat transfer.