Numerical investigation and comparison of tubular solar cavity receivers for simultaneous generation of superheated steam and hot air

Abstract

Solar cavity receivers are a crucial technology to transform solar energy into easily usable thermal energy. Various cavity receiver structures employing helical absorber tubes were investigated to provide either superheated steam or hot air efficiently. However, few studies have focused on receivers that generate both hot fluids simultaneously. The simultanoues generation can lead to a more compact and cheaper system, and can be used for applications such as a high-temperature electrolysis to produce green hydrogen or syngas. In our study, three different tubular solar cavity receivers were proposed and numerically investigated. Each receiver consists of three different processes: (1) water evaporation, (2) superheating steam, and (3) heating air. The 1D-3D model developed in our previous study was used to investigate the various aspects such as lamp-to-thermal (solar simulator was used as a light source) and exergy efficiencies. The numerical results have proven that the receiver employing both cylindrical and conical helical tubes can obtain the highest lamp-to-thermal (67.0%) and exergy efficiencies (46.9%). A parameter study was also conducted based on the chosen optimal receiver. The obtained results can become a basis for further implementation, and especially the use in high-temperature electrolysis could become crucial in a future energy system.