In this study, the development and testing of a hybrid thermal energy storage (TES) including phase change material (PCM) macro-capsules inside a vertical sensible tank is presented. The storage was specifically developed for delivering hot water on board of ships. Accordingly, a commercial PCM was selected and tested. Subsequently, the hybrid TES was designed and tested under mimicked boundary conditions at lab scale, showing the possibility of increasing the volumetric energy storage density up to 30% compared to the sensible configuration. On this basis, two numerical models were developed: a detailed one, implemented in a Fluent environment, aiming at investigating the main parameters affecting the heat transfer efficiency inside the TES and a second one, implemented in an ESP-r environment to simulate the TES as a component to be implemented inside a more complex system, thus helping its accurate design and operation through a reliable modelling phase. Both models were satisfactorily validated against the experimental results, thus being made available for future investigations and design optimization.

In the present work, the optimization of a new coating formulation was investigated, taking attention to an industrially focused research approach used for the engineering design of the adsorber. The adsorbent was a composite zeolite or silica-gel based coating applied by using new flexible polymer matrices. The FC-80 formulation represents a good compromise between mechanical stability and absorption capacity. Using the developed coating process, a new compact HEX design was developed to reach the AHP target performance with easy and fast manufacturing. The specific cooling power of the coated heat exchanger was estimated to be about 500 W/kg of adsorbent. The new coated HEX was integrated in a new adsorption chiller and has been tested by a laboratory test-rig under realistic operating conditions. Results of preliminary testing demonstrated that the prototype provides a cooling capacity of around 10 kW with a COP of 0.54.

In this work, the performance of an innovative evaporator based on water falling film was investigated. The studied evaporator has been equipped with a recirculation system to maximise the wetted surface. Tests have been carried out in a lab-scale adsorption unit connected to a test bench recently realised at Politecnico di Milano labs for evaluating heat transfer performances under realistic operating conditions. Several ad/desorption cooling cycles were performed, setting different liquid refrigerant initial contents (0.9–1.5 kg), different chilled water inlet temperatures (7–20 °C) and flow rates (200–1000 L/h) and different adsorbent bed temperatures (25–30 °C). Evaporation performance has been determined in delivered cooling capacity. Moreover, the experimental data were used to calculate the overall evaporator heat transfer conductance (UA). Experiments showed how the heat duty peaks are mainly due to the thermal level of the chilled water that enters the evaporator, not the water content inside it because this value only affects the duration of the process. Instead, the UA value does not depend on the evaporator inlet chilled water temperature and initial mass content inside the evaporator. UA is 540–570 W/K for temperatures of chilled water entering the evaporator, equal to 10–20 °C, and mass of refrigerant of 0.9–1.5 kg.

We investigated the thermal stability and corrosion effects of a promising ionic liquid (IL) to be employed as an advanced heat transfer fluid in solar thermal energy applications. Degradation tests were performed on IL samples kept in contact with various metals (steel, copper and brass) at 200 °C for different time lengths. Structural characterization of fresh and aged IL samples was carried out by high-resolution magic angle spinning nuclear magnetic resonance and Fourier transform infrared spectroscopic analyses, while headspace gas chromatography–mass spectrometry was employed to evaluate the release of volatile organic compounds. The combination of the above-mentioned techniques effectively allowed the occurrence of degradation processes due to aging to be verified.

In this work, novel silicone-SAPO34 composite materials are proposed for application in adsorption thermal energy storage systems. The innovative composite materials were obtained through a mold foaming process activated by a dehydrogenative coupling reaction between properly selected siloxane compounds. Morphology analysis by optical microscopy and measurement of the mechanical properties of the foamed materials at varying zeolite content demonstrated a quite homogeneous open-cell structure and good structural stability of the foam. Water adsorption isotherms of the adsorbent foams expanded in free space and inside paperboard were measured by a gravimetric adsorption apparatus, demonstrating that the presence of the polymeric fraction does not affect the adsorption capacity of the SAPO34 fraction added in the composite foam. Finally, main adsorption and thermodynamic properties of the proposed foam have been compared with those of other adsorbent materials, confirming the possible use of these new composite foams as adsorbent materials for adsorption thermal energy storage systems.

This study focuses on the development and testing under lab-controlled conditions of a hybrid sensible–latent thermal energy storage (TES) system for domestic hot water (DHW) provision in residential buildings. The TES system’s design is based, for the first time in the literature, on a commercial tank-in-tank architecture integrating a macro-encapsulated commercial phase change material (PCM) inside the external tank to guarantee the safe provision of DHW and increase overall energy storage density at a reasonable cost. The PCM is a salt hydrate with a nominal melting temperature of 58 °C. The overall tank-in-tank TES volume is about 540 dm³. Almost one tenth of this volume is occupied by the PCM macro-capsules. The developed TES system was comparatively tested against the same configuration operated as a sensible TES. The obtained results showed the ability of the PCM to increase the thermal inertia inside the external tank, thus guaranteeing the quite stable provision of heat to the integral DHW tank during the stand-by periods. This effect was confirmed by the PCM’s ability to achieve an energy storage capacity up to 16% higher than the reference sensible TES system.