Annamaria Buonomano

Solar heating and cooling systems by absorption and adsorption chillers driven by stationary and concentrating photovoltaic/thermal solar collectors: Modelling and simulation

Solar heating and cooling systems are a promising technology which may significantly contribute to the reduction of greenhouse gas emissions, the enhancement of energy efficiency, and the increase of renewables share in the building sector. The available literature show a high number of papers aiming at investigating solar heating and cooling systems based on heat driven and solar technologies, configurations, operating strategies, and financing issues. Nevertheless, none of the papers available in literature investigates the possibility to replace conventional solar thermal collectors by flat plat and concentrating photovoltaic/thermal systems, also producing renewable electricity. To cover this lack of knowledge, in this paper a dynamic simulation model of novel solar polygeneration heating and cooling systems is presented. Such dynamic simulation model is developed and implemented in a computer code, written in MatLab, and allows investigating the energy, economic and environmental performance of such novel solar polygeneration systems, based on both adsorption and absorption chiller technologies fed by dish-shaped concentrating and flat photovoltaic/thermal collectors. In order to show the potentiality of the presented tool, a comprehensive parametric case study is carried out to find out the optimal system configurations, as a function of crucial design and operating parameters and of weather conditions. The presented case study analysis refers to a small cluster of four buildings, including office and residential spaces, located in different European weather zones. The modelled solar polygeneration systems simultaneously produce electricity, space heating and cooling, and domestic hot water; electricity is self-consumed or delivered to the electrical grid. For comparative purposes, two different back-up system configurations, based on an electric chiller and a condensing gas-fired heater are also taken into account as conventional reference building-plant systems. By means of this systematic parametric analysis, comprehensive guidelines for system designers, practitioners and/or researchers focused on the development and use of solar heating and cooling systems are provided.

Building temperature control using an enhanced MRAC approach

One crucial aspect in building engineering is to accomplish the trade-off between reduction of energy consumption and high level thermal comfort for the occupants. To this aim, advanced control algorithms are fundamental to guarantee a certain optimality of the system performance in working conditions that can be quite different from the nominal ones due to the presence, for example, of variable external wheatear conditions or parameter uncertainties. To impose an optimal behavior of the indoor air temperature while assuring robustness to plant parameter uncertainties and external disturbances, in this paper we propose an extension of the optimal model reference adaptive scheme presented in [6] that embeds additional adaptive actions to improve tracking performance. Performance of the novel strategy are investigated both analytically, by exploiting hyperstability theory, and numerically. In particular the numerical validation has been carried out by using a detailed thermal-hygrometric simulation code (DETEC 2.1). Results confirm the effectiveness of the control in exemplar case of studies referred to buildings of different sizes and located in different European weather zones.