Efficient Energy Transfer and Storage

Solar thermal fields, consisting of large-scale installations of solar collectors, represent a key strategy for decarbonizing the thermal sector

According to Solar Heat Europe, by 2030 solar thermal in Europe could enable annual savings of approximately 33 Mt of CO₂. These systems provide domestic hot water, support low-temperature heating applications, and industrial process heat, drastically reducing reliance on fossil fuels.

By adopting vacuum-insulated collectors, thermal losses can be reduced by up to 90 %, thereby increasing overall efficiency and lowering operating costs.

Our integrated approach to efficient energy transfer and storage—combining advanced vacuum insulation, optimized fluid pipeline design, and hybrid numerical–experimental simulation—highlights the transformative potential of solar thermal systems for decarbonizing the thermal sector. By continuously advancing materials, methods, and operational practices, our work aims to provide scalable, cost-effective solutions that address the dynamic energy demands of residential and industrial applications.

Fluid Pipelines: The Impact of High-Vacuum Thermal Insulation

The thermal energy absorbed by a solar collector must be transferred to a heat-transfer fluid to carry the heat from the source (the solar field) to the demand point… [expand text]

EFESTO Group - Research material

Thermal Energy Storage

Leveraging experimental data from industrial-scale applications, our modeling and validation framework integrates computational fluid dynamics (CFD)… [expand text]

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Recent Publications and Conference Papers

TitleAuthorsYearConferenceSource title
Data-driven thermal characterization of a 1-D model for sensible stratified thermal energy storageAnacreonte A.V.; Capolupo F.; Russo R.; Vitobello R.; Musto M.202541st UIT - Naples, ItalyJournal of Physics: Conference Series
Comparison between MIX number and dimensionless exergy as performance indicators in a commercial stratified storage for future optimization of solar field operationsAnacreonte A.V.; Bianco N.; Vitobello R.; Russo R.; Musto M.2025-International Journal of Green Energy
Design and implementation of industrial hot pipeline prototypes with high vacuum multilayer insulation: Enhancing thermal performance and lifetimeCapolupo F.; D'Alessandro C.; De Maio D.; Di Giamberardino F.; Palmieri V.G.; Anacreonte A.V.; Russo R.; Musto M.2025-Applied Thermal Engineering
Design and thermal test of high-vacuum insulator for heat delivery pipesCapolupo F.; D’Alessandro C.; Strazzullo P.; Russo R.; Musto M.202440st UIT - Assisi, ItalyJournal of Physics: Conference Series
Experimental data analysis and dimensionless exergy levels in a commercial stratified thermal storageAnacreonte A.V.; Musto M.; Bianco N.; Vitobello R.; Russo R.202440st UIT - Assisi, ItalyJournal of Physics: Conference Series

Thermal Energy Storage

Leveraging experimental data from industrial-scale applications, our modeling and validation framework integrates computational fluid dynamics (CFD) simulations (COMSOL with RANS k–ε), multi-node schemes implemented in Matlab and Python, and data-driven/stochastic approaches using Python and R to accurately characterize thermal energy storage performance.
EFESTO Group - Research material
EFESTO Group - Research material
- We compared several performance indicators to assess storage efficiency, selecting metrics that can be straightforwardly computed from temperature profiles and that are valuable for optimization and control purposes.

- High-fidelity CFD modeling enabled an in-depth analysis of inlet temperature fluctuations – varying amplitude, frequency, and charging duration – on stratification. From these simulations, we derived an empirical correlation to predict stratification loss as a function of amplitude and charging time, underscoring the primary role of amplitude in thermal performance.

- A one-dimensional finite-volume multi-node model is calibrated through data-driven multi-objective optimization to fit insulation thickness and thermal conductivity parameters to experimental observations. This calibration approach also serves as a diagnostic method for detecting and quantifying insulation aging by comparing the optimized parameters against nominal reference values.

This comprehensive outlook paves the way for integrating CFD insights, simplified models, and performance indicators into predictive control strategies—such as model predictive control (MPC)—to achieve real-time storage management, enhanced scalability, and seamless smart grid integration.
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Fluid Pipelines: The Impact of High-Vacuum Thermal Insulation​

The thermal energy absorbed by a solar collector must be transferred to a heat-transfer fluid to carry the heat from the source (the solar field) to the demand point (for example domestic hot water). The pipes connecting collectors to end users, insulated with traditional materials (rock wool, polyurethane), represent a significant source of thermal losses and limit the performance of high-vacuum-based components, with increased losses when the temperature of the heat trasnfer fluid increases.

Vacuum thermal insulation, applied to heat transfer fluid pipelines, offers a solution to improve insulating performance and overcome issues related to traditional insulators, such as high thermal losses, component dimensions and dependency on atmospheric conditions.
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Our research group has conducted a comparative study between:

- Conventional Pipe: insulated with polyurethane or rock wool;
- High-Vacuum Multilayer Insulation (HVMLI) Pipe: “pipe-in-pipe” configuration with an evacuated gap and getter pills to maintain vacuum over years.

The HVMLI is widely used in cryogenic applications (i.e. temperatures < -150 °C) reaching values of λeq as low as 10-5 Wm-1K-1 at -196 °C. In the mid-temperature range (100 °C – 250 °C) it still reduces radial thermal losses by nearly a factor of 10, resulting in an extremely lightweight, eco-friendly device with very high thermal insulation performance. The experimental characterization of the main parameters (materials, number of layers, density, geometric dimensions) is carried out through calorimetric measurements capable of detecting heat powers on the order of 1 W with 10 % resolution.

The improved thermal insulation is obtained together with a reduction of the component size by a factor of 2.5. The improved thermal insulation is obtained together with a reduction of the component size by a factor of 2.5. The 10 layer HVMLI reduces the equivalent thermal conductivity up to a factor of 20. If you want to know more, follow the link to the journal paper: https://doi.org/10.1016/j.applthermaleng.2024.125373

The vacuum thermal insulation ensures thermal properties remain stable and independent of the environmental conditions, while the properties of insulating materials can change significantly under environmental conditions.
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