Paolo Iodice

Optimizing heat transfer in the evaporator tubes is essential for obtaining optimal coefficients. Deviation from ideal nucleated boiling configurations can lead to rapid transitions to film boiling conditions, compromising the exchange coefficients. Detecting critical bubble flow conditions is invaluable in preventing thermal overloads and safeguarding operational integrity. The aim is to detect the type of bubble motion established in the ducts using non-intrusive techniques. To achieve this aim, accelerometric devices detect the vibrations induced by the passage of bubbles. The bubble's movement is also recorded contextually by a fast video camera capable of detecting images through a vertical transparent quartz duct. The accelerometric data, processed using discriminant analysis theory and then associated with the recorded images, give a good relationship, more than 95%, between the motion of the bubbles and their behavior characteristics. The latter in this work is represented on the plane of the phases.

To address the growing problem of pollution and global warming, it is necessary to steer the development of innovative technologies towards systems with minimal carbon dioxide production. Thermal storage plays a crucial role in solar systems as it bridges the gap between resource availability and energy demand, thereby enhancing the economic viability of the system and ensuring energy continuity during periods of usage. Thermal energy storage methods consist of sensible heat storage, which involves storing energy using temperature differences; latent heat storage, which utilizes the latent heat of phase change materials; and thermochemical heat storage, which utilizes reversible chemical reactions through thermochemical materials. The objective of this review paper is to explore significant research contributions that focus on practical applications and scientific aspects of thermal energy storage materials and procedures. For each type of storage, different materials have been examined, taking into consideration the most recent studies, both for medium and long-term storage and, when possible, comparing methodologies for the same purpose. It has been observed that TCHS systems have the potential to reduce the volume of chemical storage tanks by 34 times using chemical reactions. Among the SHS materials, water, molten salts, and graphite exhibit the highest energy density, with graphite also possessing remarkable thermal conductivity. Nanoparticles can enhance the thermophysical properties of TES materials by increasing their thermal conductivity and wettability and improving intermolecular characteristics. The use of biobased PCMs for applications that do not require very high temperatures allows for maximizing the efficiency of such storage systems.