STUDIO DELLA COMBUSTIONE IN SISTEMI ENERGETICI PER LA MICROCOGENERAZIONE

In recent years, distributed microcogeneration systems have received a renewed attention. In this work two different microcogenerative energetic systems have been analyzed and presented: micro gas turbine (MGT) and thermophotovoltaic (TPV) systems. The knowledge of combustion process inside combustion chamber of these systems is one of the most crictical aspects in the analysis of the performance and of the operation conditions. A CFD analysis, constituted by solid modeling, grid generation and 3D thermofluidynamic analysis, has been carried out in order to investigate the behavior of three different MGT combustion chambers. The analysis of MGT combustion chambers has been mainly focused on the different combustion models implemented in the numerical code used for all numerical simulations (ANSYS CFX). In particular, the beaviour of four different combustion chambers has been analized in terms of global performances. Instead, the numerical analysis of the TPV system has been focused on the analysis of an entire furnace which use a radiative burner as combustion device. The realized numerical models are complex, but, in general, the results obtained can satisfactory reproduce either experimental or literature data, and they demonstrated to be a valuable tool to evaluate combustion phenomena inside the systems under investigation. The opportunity to simulate real combustor chambers gives the possibility to check and validate the developed numerical models at various working conditions. In other cases, the CFD analysis demonstrated to be strongly limited by the numerical codes capability and by the computational effort requested by the simulations. The first result of this work is constituted by a consolidate experience on the whole CFD analysis (starting from geometrical modeling to result post-processing). Then, regarding the MGT combustion chamber simulations, a number of modifications to combustion chamber geometry and to operating conditions have been proposed in order to optimize the combustor behavior with a Biogas feeding. Regarding TPV system, numerical model allowed the simulation of the entire systems and it demonstrated to be an important tool for numerical and experimental optimization of TPV applications. Moreover, it represents the first step for the development of an optimized cogenerative thermophotovoltaic system.