FOSSA , Marco

Tesi di Dottorato, Roma

The performance of impedance probes for measuring the conductance of gas–liquid mixtures in horizontal pipes is here studied by means of the numerical solution of Laplace problem. In particular the work is aimed at optimising the probe geometry in order to improve the probe response both in terms of linearity and in terms of spatial resolution...

Calculations are performed to study the behavior of air-water mixtures in vertical flows employing a simple model for the description of mass, momentum, and energy transfer in annular gas-liquid flows. The model is applied to various flow conditions including thermal nonequilibrium and variable cross section ducts. Theoretical results agree...

Borehole heat exchangers (BHEs) are the most frequently adopted solution for ground coupled heat pump applications. In most installations, BHEs also represent the most important cost item, and a careful design analysis is needed to either assure long time performance or reduce the payback period, both parameters related to overall BHE length....

Ground coupled heat pumps are systems combining a heat pump with a ground heat exchanger for building heating and cooling purposes. Borehole heat exchangers (BHE) are the most frequently adopted solution for ground-assisted heat pump applications, and in most installations, they represent the most important cost item. For this reasons, a...

CERN Report, 1992

In this article, the ASHRAE method for borehole heat exchanger field design is deeply discussed in order to trace its theory and physical meaning. The aim of the article is corroborate previous studies in order to demonstrate that the current version of the method is not suitable for a reliable sizing of the borehole field since the criteria...

Experiments have been carried out to analyze the evolution of the air/water flow structure along a horizontal 60 mm i.d. straight pipe. Plug and slug flow regimes were observed. In order to investigate the local structure of the flow, dynamic void fraction measurements have been performed by means of ring impedance probes. From dynamic void...

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Nel presente articolo si intendono descrivere i principi fisici di base che regolano il processo di scambio termico tra il terreno ed un sistema di scambiatori interrati nelle applicazioni a pompa di calore a circuito chiuso (Ground Coupled Heat Pumps, GCHP). Questa breve analisi riguarderà gli scambiatori interrati verticali (Borehole Heat...

Processes involving heat transfer from a humid air stream to a cold plate, with simultaneous deposition of frost, are of great importance in a variety of refrigeration equipment. In this paper, frost growth on a cold, vertical plate in free convection has been experimentally investigated. The cold plate (0.095 m high, 0.282 m wide) was placed...

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Heat transfer from the ground to a carrier fluid in ground coupled heat pump applications where vertical borehole heat exchangers (BHE) are present, is strongly influenced by the thermal resistance between the borehole surface and the fluid, and between the two (or more) pipes inside the borehole. In this systems the main contribution to the...

Nel presente lavoro lo studio delle caratteristiche dell'interfaccia liquido-gas di efflussi bifase viene affrontato con l'ausilio di sonde di tipo resistivocon elettrodi non intrusivi. L'indagine sperimentale si avvale del supporto della teoria, qui presentata in rassegna, sviluppata negli ultimi decenni da altri autori. Il dispositivo messo a...

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