Experimental investigations of porous materials in high temperature thermal energy storage systems

• Published in: Solar energy 2011-07, Vol.85 (7), p.1371-1380
• Main Authors: Wu, Z.G., Zhao, C.Y.
• Format: Article
• Language: English
• Subjects: Applied sciences; Direct energy conversion and energy accumulation; Electrical engineering. Electrical power engineering; Electrical power engineering; Energy; Energy accumulation; Energy. Thermal use of fuels; Exact sciences and technology; Expanded graphite; Heat transfer; Heating; High temperature; Liquids; Metal foam; Nanocomposites; Nanostructure; Phase change materials; Porous materials; Sodium nitrate (NaNO 3); Solar energy; Storage systems; Theoretical studies. Data and constants. Metering; Thermal energy; Transport and storage of energy
• ISSN: 0038-092X; 1471-1257
• DOI: 10.1016/j.solener.2011.03.021

► The heat transfer rate can be enhanced by porous materials by 2.5 times in the solid region. ► The natural convection is weakened by the porous structures. ► Two heating methods are investigated to examine the natural convection effect. ► The issue of corrosion process is briefly discussed. In this paper, the feasibility of using porous materials such as metal foams and expanded graphite to enhance the heat transfer capability of PCMs in high temperature thermal energy storage system is experimentally investigated. Experimental results showed that the heat transfer rate can be enhanced through addition of the porous materials by 2.5 times compared to that of pure NaNO 3 in the heating process from 250–300 °C. However the heat transfer rate could be reduced by half in the liquid region since the natural convection can be severely suppressed by the porous structures. In an attempt to further reveal the natural convection effect in PCMs embedded in porous materials, two heating methods (boundary conditions) are examined. Finally the issue of corrosion process is briefly discussed.