Heat transfer and storage performance of steam methane reforming in tubular reactor with focused solar simulator. (1st January 2019)

• Record Type: Journal Article
• Authors: Gu, Rong; Ding, Jing; Wang, Yarong; Yuan, Qinquan; Wang, Weilong; Lu, Jianfeng
• Is Part Of: Applied energy. Volume 233/234(2019)
• Page Start: 789
• Page End: 801
• Publication Date: 2019-01-01
• Subjects: Steam methane reforming -- Thermochemical energy storage -- Tubular reactor -- Focused solar simulator -- Simulation; Power (Mechanics) -- Periodicals; Energy conservation -- Periodicals; Energy conversion -- Periodicals; 621.042
• DOI: 10.1016/j.apenergy.2018.10.072
• Languages: English
• ISSNs: 0306-2619

Abstract

Highlights: Thermochemical energy storage experiment is reported using focused solar simulator. Local and integral energy transport and storage performance are both revealed. Maximum reaction rate appears before focal point and reverse reaction is near the end. Thermochemical efficiency has maximum with proper bed length and porosity of 0.45. Insulation and coating improve thermochemical energy storage efficiency up to 34.8%. Abstract: Steam methane reforming is suitable for thermochemical energy storage because of its large reaction enthalpy and high hydrogen content in reaction products. In this paper, heat transfer and storage performance of steam methane reforming in a tubular reactor heated by focused solar simulator is experimental demonstrated and numerically analyzed. According to experimental results, methane conversion remarkably decreases with inlet flow rate rising, while thermochemical energy storage efficiency first increases for more reactants and then decreases with methane conversion dropping. As incident energy flux rises, methane conversion increases with bed temperature rising, and the thermochemical energy storage efficiency reaches its maximum of 11.3% with central heat flux of 285.6 kW/m 2 . Three-dimensional transport and volumetric reaction model with concentrated energy flux boundary condition is established and validated, and local and integral energy transport and storage performance are further analyzed. Along flow direction, the maximum reaction rate appears before the focal point with maximum energy flux. The tendencies of methane conversion and thermochemical energy storage efficiency are very similar under different inlet conditions, and higher inlet temperature and appropriate steam to methane ratio benefit thermochemical energy storage. The structures of catalyst bed and reactor are critical important for thermochemical energy storage process. As bed length increases, the methane conversion and thermochemical energy storage efficiency first increase with the increase of positive reaction and then decrease with the increase of reverse reaction, and the optimal length is a little larger than focal spot diameter. When bed porosity is increased, the methane conversion and thermochemical energy storage efficiency first increases with the flow resistance decreasing and then decreases with catalyst amount decreasing, and optimal porosity is 0.45. Heat loss in heating side of bed region play major role in heat storage, and the thermochemical energy storage efficiency can be improved to 34.8% by using insulation and coating.