Development of cost efficient solar receiver tube with a novel tandem absorber system

• Published in: Applied thermal engineering 2016-10, Vol.109 (PB), p.988-996
• Main Authors: Shiva Prasad, M., Chandra Sekhar Reddy, K., Sakthivel, S.
• Format: Article
• Language: English
• Subjects: Antireflective layer; Cr-Mn-Fe composite oxide; Nanoporous; SiO2 nanoparticle layer; Tandem absorber layer; ZrO2-SiO2
• ISSN: 1359-4311
• DOI: 10.1016/j.applthermaleng.2016.05.163

•A novel tandem absorber was designed for high performance Organic Ranking Cycle (ORC) based solar thermal applications.•Tandem consists of Cr-Mn-Fe oxides/ZrO2-SiO2 or Cr-Mn-Fe oxides/ZrO2-SiO2/SiO2 layer.•Two layers tandem exhibits a high absorptance (α=0.94.9) and low thermal emittance (ε=0.122 at 300°C).•This tandem shows an excellent thermal and corrosion stabilities. New single layer, double layer and triple layer absorber tandems were designed and developed for high performance Organic Ranking Cycle (ORC) based solar thermal applications. A Cr-Mn-Fe composite oxide based absorber layer is devolved by controlled chemical oxidation and designed to have a nanoporous structure. It is covered with double antireflective layers a ZrO2-SiO2 nanocomposite layer developed by the sol-gel route and a porous SiO2 layer obtained from SiO2 nanoparticle suspension. Double and triple layer tandem absorbers were developed by a combination of chemical, sol-gel and nanoparticle suspension methods. By varying process parameters like duration, temperature and withdrawal speed, different combinations of Cr-Mn-Fe oxides/ZrO2-SiO2 double layer tandem and Cr-Mn-Fe oxides/ZrO2-SiO2/SiO2 triple layer tandem composite absorber layers with varying refractive indices were developed on an economical variety of SS substrate. The optimized thickness of the absorber layer along with the antireflective layers shown a high absorptance (α=94.9) and low warm emittance (ε=0.122 at 300°C). More specifically, this novel double layer tandem coating has excellent optical properties along with high corrosion resistance (withstands>200h in salt spray test). It has good thermal stability in an open air atmosphere and is well suited for low and medium temperature solar thermal applications.