Thermal energy storage (TES) systems are crucial for industries to overcome the temporal misalignment between heat demand and availability, while also reducing greenhouse gas emissions. This is fundamental for increasing industrial production efficiency and promoting renewable energy sources, such as solar energy. Among various TES solutions (sensible, latent, and thermochemical), combined sensible/latent heat TES (CSLHTES) is attracting more interest. It combines the ideal characteristics of individual sensible or latent heat storage technologies: high stored energy density, compactness, high efficiency, stable heat supply temperature, and good power output. This work experimentally evaluates the thermal behavior and potential improvements of a CSLHTES system. This system, named HyTES, consists of two series-connected TES units—one sensible and one latent—operating within a 180–280 °C range, to meet typical industrial application requirements. A test procedure was developed to define key performance indexes (KPIs). The results confirm that CSLHTES systems generally show improved performance compared to individual units. This indicates that further analysis of this approach is justified, moving beyond just energy and exergy perspectives to also include economic and environmental impacts.

Concentrated Solar Power (CSP) plants integrated with Thermal Energy Storage (TES) represent a promising renewable energy source for generating heat and power. Binary molten salt mixtures, commonly referred to as Solar Salts, are utilized as effective heat transfer fluids and storage media due to their thermal stability and favorable thermophysical properties. However, these mixtures pose significant challenges due to their high solidification temperatures, around 240 °C, which can compromise the longevity and reliability of critical system components such as pressure sensors and bellows seal globe valves. Thus, it is essential to characterize their performance, assess their reliability under various conditions, and understand their failure mechanisms, particularly in relation to temperature fluctuations affecting the fluid’s viscosity. This article discusses experimental tests conducted on a pressure sensor and a bellows seal globe valve, both designed for direct contact with molten salts in CSP environments, at the ENEA Casaccia Research Center laboratory in Rome. The methodology for conducting these experimental tests is detailed, and guidelines are outlined to optimize plant operation. The findings provide essential insights for improving component design and maintenance to minimize unplanned plant downtime. They also offer methodologies for installing measurement instruments and electrical heating systems on the components.

The estimation of the average daily, monthly and annual direct normal solar irradiation (DNI) was done in the region hosting the Mario Zucchelli Station, in the bay of Terra Nova (Antarctica). Estimates are based on measurements of direct normal (DNI), horizontal global (GHI) and horizontal diffuse (Diff.HI) irradiations, observed by a solar-metric acquisition station installed during the XXVIII scientific expedition carried out in the austral summer 2012/2013 as part of the National Plan of Research in Antarctica (PNRA). The contemporary observations of all three irradiations allowed the setting up of the model for the estimation of the DNI starting from the values of the GHI only, validated for the weather conditions of the Antarctic region. Subsequently, the long-time data reconstruction of the DNI values thanks to the availability of several years' hourly measurements of GHI at the Mario Zucchelli base has been carried out using the meteorological acquisition data installed both at the base and in places scattered around it. The final results make feasible the estimation of solar potential for concentrated solar technology according to long measurements of GHI. Overall, we propose a clean technology based on a renewable power plant and a specific example with a tendency toward a decreased human carbon footprint in the atmosphere of this protected area.

Concentrated Solar Power (CSP) plants integrated with Thermal Energy Storage (TES) represent a promising renewable energy source for generating heat and power. Binary molten salt mixtures, commonly referred to as Solar Salts, are utilized as effective heat transfer fluids and storage media due to their thermal stability and favorable thermophysical properties. However, these mixtures pose significant challenges due to their high solidification temperatures, around 240 °C, which can compromise the longevity and reliability of critical system components such as pressure sensors and bellows seal globe valves. Thus, it is essential to characterize their performance, assess their reliability under various conditions, and understand their failure mechanisms, particularly in relation to temperature fluctuations affecting the fluid’s viscosity. This article discusses experimental tests conducted on a pressure sensor and a bellows seal globe valve, both designed for direct contact with molten salts in CSP environments, at the ENEA Casaccia Research Center laboratory in Rome. The methodology for conducting these experimental tests is detailed, and guidelines are outlined to optimize plant operation. The findings provide essential insights for improving component design and maintenance to minimize unplanned plant downtime. They also offer methodologies for installing measurement instruments and electrical heating systems on the components.

Parabolic trough collector (PTC) plants that use solar salt as a heat transfer fluid face operational challenges due to the salt’s relatively high solidification temperature of around 240 °C, which can compromise reliability if solidification occurs within receiver tubes or piping. While electric tracing cables are typically used to heat piping, they cannot be installed on PTC receivers due to the presence of external glass covers. As an alternative, impedance heating can be employed, applying voltage directly to the steel receivers, which act as resistive heaters. This study presents experimental results on the phase-change behavior of solar salt within receivers, focusing on melting and solidification times. Tests were conducted using two dedicated receivers under vacuum and non-vacuum conditions. Under vacuum, complete melting was achieved at 4.5 V and 1.43 kW in 5.5 h, while solidification from 270 °C took about 4 h, progressing inward from the tube connections. For non-evacuated receivers, 7 V and 3.2 kW were needed for melting in 5.6 h, and solidification at 270 °C was completed in 1.45 h. These outcomes illustrate that non-evacuated tubes require nearly twice the power and have a 2.8-fold increase in heat loss rate, offering quantitative guidance for vacuum loss detection in PTC systems.