Modellazione matematica ed analisi sperimentale di un'unità ORC solare

The doctoral thesis activity that follows had, as its object, the dynamic modeling of a micro-cogeneration system (MCHP). It integrates the technology of solar col lectors to vacuum plates (EFPC) with the technology of recovery plants based on Rankine cycles making use, for temperature reasons, of organic fluids (ORC -based recovery units). Contextual coverage of thermal needs of a domestic user has been considered together with the electrical needs. The low grade thermal energy recovered by the thermal solar collectors feeds the evaporator of the ORC-based recovery unit whose aim is to produce electricity whose power is of the order of 1kW, to be allocated to self-consumption, accumulation or sale to the network. The thermal energy exchanged at the condebnser is intended for the accumulation or immediate coverage of the domestic hot water requirements from the domestic utilities. The addition of a hot water storage system upstream of the evaporator ensures a continuous operation of the ORC-based unit (operating in off design conditions too) until thermal power was available; this allowed to mitigatethe ne gative effects of the daily solar energy fluctuations. The hot water system can be used also when a high demand of thermal energy woud be requested. This integration allows the restoration of optimal conditions of the operations of the solar collection section which in this way operates continuously recovering solar energy and allowing the feeding of an ORC-based unit producing electricity as close as possible to steady opertating conditions, even though in off design operation. The overall system has been modelled inside a Matlab environment, starting from the potential of the ORCmKit solver for the electricity generation. The resolution of mass and energy equations in steady off design conditions was the base of the accumulation of the thermal energy inside the refeeding the recovery unit as well as inside that one which, at the condenser, allows to fulfil the low temperature thermal energy needs from a domestic request. The model of the system allowed to design a ORC-based unit which has been built and tested demonstrating the feasibility of the cogenerating unit, experimentally reproducing the typical situations produced by a solar irradiation and thermal energy demands.