A multi-variable multi-objective methodology applied to energy conversion systems

World climate change and global warming increase are two urgent and strategic issues that national and international governments have to face, and different scenarios aimed to estimate the world energy demand were realized by several research centers: each scenario distinguishes itself by energy policies over the years, and the desirable one requires many efforts to keep the temperature increase below 2°C above pre-industrial level. These efforts imply challenging targets on both primary and final energy employment, and this thesis is focused on two of them: improvement of renewable energy exploitation and reduction of final energy consumption, and energy conversion systems able to efficiently achieve these targets are cogenerated distributed plants, in particular the small scale. Nevertheless, in order to achieve significant primary energy saving, combined heat and power plants need to be designed with a substantial thermal power exploitation, as well as the design need reliable and congruent system models to evaluate the plant performances. The methodology carried out in this doctorate course was focused on the analysis of these topics and it was made by two main elements, an energy conversion system model, which describes the peculiar studied case, and a multi-variable multi-objective optimization algorithm, which depends on the specific application. In particular, two different applications of the methodology were realized, one aimed at designing the more efficient energy interaction between energy system and user and one aimed at validate thermodynamic models and experimental data congruence; the first application concerned combined heat and power plants based on internal combustion engine and gas turbine, while the second application was performed on micro gas turbines and pyro-gasification biomass plant. The methodology showed to be a potentially powerful tool about conversion energy systems analysis, due to the relevant primary energy saving related to designed cogenerated power plant and to the analysis of reliability performed on mathematical models of energy conversion systems.