Thermal Efficiency of a New Prototype of Evacuated Tube Collector using Sn-Al2O3 as a Selective Solar Absorber


  • Warisa WAMAE School of Renewable Energy and Smart Grid Technology, Naresuan University, Phitsanulok 65000
  • Tawat SURIWONG School of Renewable Energy and Smart Grid Technology, Naresuan University, Phitsanulok 65000
  • Thotsaphon THRERUJIRAPAPONG Department of Materials and Production Technology Engineering, Faculty of Engineering, King Mongkut's University of Technology North Bangkok, Bangkok 10800



Evacuated tube collector, Selective solar absorber, Anodization, Absorptance, Thermal emittance


Three tin pigmented aluminium oxide (Sn-Al2O3)films were prepared with different tin content using an anodization process, which is applied as a selective solar absorber in a new prototype of evacuated tube collector (ETC). The morphology and distribution of elements on the coatings were characterized using a Scanning Electron Microscope (SEM) equipped with an Energy Dispersive X-ray (EDX) analyzer. The spectrally selective properties, defined as the ratio of solar absorptance (αsol) to thermal emittance (εtherm) were examined. In order to investigate the thermal performance of ETC using Sn-Al2O3 on an Al fin as a solar receiver, thermal efficiency (η) of the ETC was collected under steady-state conditions, as prescribed by ISO 9806-1 standard. The results, of the Sn-Al2O3 coatings reached a darker black colour with an increase in the colouring time. The samples were composed of different contents of Sn in the Al2O3 layer. The solar selectivity (αsol/εtherm) significantly increased with the increases in Sn content. The maximum thermal efficiency (ηmax) of the ETC under the nearly constant heat loss coefficient (UL), was obviously increased with the increasing Sn content. Therefore, the Sn-Al2O3 with different Sn contents is a good candidate for selective solar absorbers in a new prototype of ETC.


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How to Cite

WAMAE, W., SURIWONG, T., & THRERUJIRAPAPONG, T. (2018). Thermal Efficiency of a New Prototype of Evacuated Tube Collector using Sn-Al2O3 as a Selective Solar Absorber. Walailak Journal of Science and Technology (WJST), 15(11), 793–802.



Research Article