Nan Sheng,Wenlong Li,Shasha Lu,Renjie Liu,Songcen Shi,Hongzhi Liu,Chunyu Zhu
Phase change thermal storage represents a valid solution to the problem of renewable energy indirection. Metals have a high heat storage density and high thermal conductivity, making them a promising material for high-temperature phase change materials, yet limited in application by corrosion. As a solution, a boiling and cold pressing with subsequent calcination method was proposed for the development of shape-stabilized PCMs with Al as a phase change material and Al 2 O 3 as the matrix. A three-step preparation process was involved: (1) Generation of precursor shell layer on the surface of Al micropowder by boiling water treatment. This step was crucial for leakage prevention. (2) Stabilization and composite formation of the phase change material by cold pressing. In this step, we carefully studied the effect of pressure on the structural strength of composite phase change materials (PCCMs) and finally concluded that 10 MPa was the optimal cold pressure. (3) Formation of structurally stable PCCM was finalized by thermal oxidation treatment. The phase transition temperature and latent heat of phase transition of PCCM were 653°C and 68 J/g, respectively. Importantly, these phase transition properties remained consistent over 100 thermal cycles, indicating a good cycling property. These results inform the application of metallic Al in high-temperature thermal storage.
While thermal energy storage (TES) systems are becoming crucial to the stable operation of solar power plants, molten salt packed bed thermal energy storage (PBTES) systems attracted widespread attention due to their wide operating temperature range and low cost. However, achieving high-efficiency thermal storage systems is still a datum challenge to meet the higher energy demand, as well as sustainable development and utilization of renewable energy systems. This study developed spherical capsules employing nanocomposite salts (MgCl 2 –KCl–NaCl/Al 2 O 3 nanoparticles) as composite phase change materials to experimentally study the heat storage process of a high-temperature PBTES prototype experimental system. Also, the heat storage performance of the PBTES system under different operating conditions is further investigated. The results showed that the nanocomposite salt gradually melted along the flow direction of the heat transfer fluid by exhibiting three-stage characteristics including solid phase sensible heat, phase change latent heat, and liquid phase sensible heat. Also, the temperature difference inside and outside the capsules showed the characteristics of peak-trough-peak. The PBTES system reached a heat storage density of 1290.51 MJ m −3 at a thermal efficiency of 86.95 %. The average heat storage rate increased by 49.55 % and the heat storage time was shortened by 29.67 % when the blower speed was increased from 800 r·min −1 to 1200 r·min −1 . The experimental results implied that the PBTES system encapsulating nanocomposite salts has excellent thermal performance. This study demonstrated solving the problems of insufficient thermal energy supply in time or space and improving energy utilization could result in a high-efficiency thermal storage system.
危险品化学品经营许可证（带存储）