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In the present work, two different types of heat exchangers are experimentally compared, namely a fin-and-tubes custom made HEX and a commercial asymmetric plate heat exchanger, for the application with phase change materials. In particular, the two devices were tested in a specifically designed testing rig located at CNR-ITAE and suitable for the characterization of thermal energy storages. The testing bench allows simulating a heat source up to 100°C (e.g. solar thermal collectors, low-grade waste heat) and to set the desired discharge temperature in the range 20°C-80°C. The phase change material with which the exchangers were filled, is a commercial paraffin (Plus ICE A82), having a nominal melting temperature of 82°C. The experimental results on charge and discharge tests, realized with the same protocol, were used for a comparison of the systems, through the identification of suitable performance figures and Key Performance Indicators, such as material-to-metal ratio, heat storage density, maximum and average power achievable and effectiveness of the system. The results show that, for the tested material, characterised by a very low thermal conductivity (i.e. about 0.2 W/mK), the selected plate heat exchanger allows a better exploitation of the heat stored inside the material, letting at the same time to reach a power output in the range 1-10 kW.

The hot water tanks are the typical thermal storage systems in Solar Domestic Hot Water (SDHW) plants. In this paper a new model for ESP-r has been developed, in order to simulate a tank in tank heat storage. The tank in tank system is made up of two tanks in which the smaller, storing potable hot water, is contained in a larger buffer filled with heating-circuit water. The developed model is an enhanced version of a component already available in ESP-r. Experimental results are used to identify some parameters and to perform the validation of the developed code.

In this work, a dynamic model for the simulation of solar cooling systems employing adsorption chillers has been evaluated. The model, realised with the commercial software TRNSYS, has been implemented to quantify the effect of different operational and design parameters on the overall performances of solar cooling systems in three different Italian cities (Milan, Rome, Messina). An economic analysis has been performed for an optimised system, in order to evaluate the payback time of the different solutions compared to a traditional air conditioning system, considering also the state incentives introduced since 2012.