Gianluca Ambrosetti

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This thesis presents an investigation of the models describing electrical conductivity in polymer nanocomposites, which consist in more or less random dispersions of nanometric conductive llers like carbon nanotubes, nano bers or graphene sheets in a polymer matrix. The investigation is carried out mainly through simulations with ad-hoc developed algorithms(More)
The spectral specular reflectance of conventional and novel reflective materials for solar concentrators is measured with an acceptance angle of 17.5 mrad over the wavelength range 300-2500 nm at incidence angles 15-60° using a spectroscopic goniometry system. The same experimental setup is used to determine the spectral narrow-angle transmittance of(More)
We consider the limit of geometric concentration for a focusing concave mirror, e.g., a parabolic trough or dish, designed to collect all radiation within a finite acceptance angle and direct it to a receiver with a flat or circular cross-section. While a concentrator with a parabolic cross-section indeed achieves this limit, it is not the only geometry(More)
Solar energy is typically converted into electrical energy or collected as thermal energy. Co-generation of electricity and low-grade heat allows a more efficient use of the solar spectrum. To this end, a prototype of a high-concentration photovoltaic thermal (HCPVT) system is demonstrated. It is based on low-cost optical concentrator materials, a(More)
The two-stage line-to-point focus solar concentrator with tracking secondary optics is introduced. Its design aims to reduce the cost per m(2) of collecting aperture by maintaining a one-axis tracking trough as the primary concentrator, while allowing the thermodynamic limit of concentration in 2D of 215× to be significantly surpassed by the implementation(More)
Parabolic trough concentrating solar power (CSP) has long proven to be among the most viable options for large-scale solar electricity generation. However, conventional solar parabolic trough plants suffer from several technical and economical drawbacks. These include most notably a maximum operating temperature limited to below 450 °C, a difficulty(More)
Catalytic hydrothermal gasification is a promising technology which allows the conversion of wet biomass into methane rich syngas. It consists of three major steps, in which thermal energy has to be supplied at different temperature levels, leading to multiple products, such as clean water, nutrients/salts and methane rich syngas. Microalgae have an(More)
Ethanol production sites utilizing sugarcane as feedstock are usually located in regions with high land availability and decent solar radiation. This offers the opportunity to cover parts of the process energy demand with concentrated solar power (CSP) and thereby increase the fuel production and carbon conversion efficiency. A plant is examined that(More)
While nonimaging concentrators can approach the thermodynamic limit of concentration, they generally suffer from poor compactness when designed for small acceptance angles, e.g., to capture direct solar irradiation. Symmetric two-stage systems utilizing an image-forming primary parabolic concentrator in tandem with a nonimaging secondary concentrator(More)
In conductor-insulator composites in which the conducting particles are dispersed in an insulating continuous matrix the electrical connectedness is established by interparticle quantum tunneling. A recent formulation of the transport problem in this kind of composites treats each conducting particle as electrically connected to all others via tunneling(More)
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