Cost Efficient Receiver Tube Technology for Eco-Friendly Concentrated Solar Thermal Applications

Authors: M. Shiva Prasad, S. R. Atchuta, T. Vijayaraghavan, S. Sakthivel

Abstract:

The world is in need of efficient energy conversion technologies which are affordable, accessible, and sustainable with eco-friendly nature. Solar energy is one of the cornerstones for the world’s economic growth because of its abundancy with zero carbon pollution. Among the various solar energy conversion technologies, solar thermal technology has attracted a substantial renewed interest due to its diversity and compatibility in various applications. Solar thermal systems employ concentrators, tracking systems and heat engines for electricity generation which lead to high cost and complexity in comparison with photovoltaics; however, it is compatible with distinct thermal energy storage capability and dispatchable electricity which creates a tremendous attraction. Apart from that, employing cost-effective solar selective receiver tube in a concentrating solar thermal (CST) system improves the energy conversion efficiency and directly reduces the cost of technology. In addition, the development of solar receiver tubes by low cost methods which can offer high optical properties and corrosion resistance in an open-air atmosphere would be beneficial for low and medium temperature applications. In this regard, our work opens up an approach which has the potential to achieve cost-effective energy conversion. We have developed a highly selective tandem absorber coating through a facile wet chemical route by a combination of chemical oxidation, sol-gel, and nanoparticle coating methods. The developed tandem absorber coating has gradient refractive index nature on stainless steel (SS 304) and exhibited high optical properties (α ≤ 0.95 & ε ≤ 0.14). The first absorber layer (Cr-Mn-Fe oxides) developed by controlled oxidation of SS 304 in a chemical bath reactor. A second composite layer of ZrO₂-SiO₂ has been applied on the chemically oxidized substrate by So-gel dip coating method to serve as optical enhancing and corrosion resistant layer. Finally, an antireflective layer (MgF₂) has been deposited on the second layer, to achieve > 95% of absorption. The developed tandem layer exhibited good thermal stability up to 250 °C in open air atmospheric condition and superior corrosion resistance (withstands for > 200h in salt spray test (ASTM B117)). After the successful development of a coating with targeted properties at a laboratory scale, a prototype of the 1 m tube has been demonstrated with excellent uniformity and reproducibility. Moreover, it has been validated under standard laboratory test condition as well as in field condition with a comparison of the commercial receiver tube. The presented strategy can be widely adapted to develop highly selective coatings for a variety of CST applications ranging from hot water, solar desalination, and industrial process heat and power generation. The high-performance, cost-effective medium temperature receiver tube technology has attracted many industries, and recently the technology has been transferred to Indian industry.

Keywords: Concentrated solar thermal system, solar selective coating, tandem absorber, ultralow refractive index.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.3300604

References:

[1] O.P. Agnihotri, B.K. Gupta, Solar selective surfaces, first ed., A Wiley Interscience publication, New York, 1981.
[2] H.G. Craighead, R.A. Buhrman, “Optical-properties of selectively absorbing Ni-Al2O3 composite films”, Appl. Phys. Lett. 31 (1977) 423–425.
[3] B.O. Seraphin, “Chemical vapor deposition of thin semiconductor films for solar energy conversion”, Thin Solid Films 39 (1976) 87–94.
[4] W.F. Bogaerts, C.M. Lampert, “Materials for photothermal solar energy conversion”, J. Mater. Sci. 18 (1983) 2847–2875.
[5] C.E. Kennedy, Review of Mid- to High-Temperature Solar Selective Absorber Materials, NREL/TP-520-31267, National Renewable Energy Laboratory, Golden, CO, 2002.
[6] L. Kaluza, A. SURCA-vuk, B. Orel, “Structural and IR spectroscopic analysis of sol-gel processed CuFeMnO4 spinel and CuFeMnO4/silica films for solar absorbers”, J. Sol.- Gel Sci. Technol. 20 (2001) 61–83.
[7] L. Kaluza, B. OrelL, G. Drazic, M. Kohl, “Sol – gel derived CuCoMnOx spinel coatings for solar absorbers: structural and optical properties”, Sol. Energy Mater. Sol. Cell. 70 (2001) 187–201.
[8] J. Vince, A. Šurca Vuk, U. Opara Krašovec, B. Orel, M. Köhl, M. Heck, “Solar absorber coatings based on CoCuMnOx spinels prepared via the sol-gel process: structural and optical properties”, Sol. Energy Mater. Sol. Cells 79 (2003) 313–330.
[9] Joly, Y. Antonetti, M. Python, M. Gonzalez, T. Gascou, J.L. Scartezzini, A. Schüler, “Novel black selective coating for tubular solar absorbers based on a sol-gel method”, Sol. Energy 94 (2013) 233–239.
[10] M.S. Prasad, B. Mallikarjun, M. Ramakrishna, J. Joarder, B. Sobha, S. Sakthivel, “Zirconia nanoparticles embedded spinel selective absorber coating for high performance in open atmospheric condition”, Sol. Energy Mater. Sol. Cells 174 (2018) 423-432.
[11] A. Srinivasa Rao, S. Sakthivel, “A highly thermally stable Mn–Cu–Fe composite oxide based solar selective absorber layer with low thermal loss at high temperature”, Alloys Compd., 644 (2015), 906-9151.
[12] V.C. Sharma, A. Sharma, P. Ilenikhena, “Chemical oxidation and spectral selectivity of Austenitic stainless steel AISI 321(For use in solar-Energy Application)”, Energy 13 (1988) 749–754.
[13] C.S. Uma, L.K. Malhotra, K.L. Chopra, “spectrally selective surfaces on stainless steel produced by chemical conversion”, Thin Solid Films 147 (1987) 243–249.
[14] M. Shiva Prasad, K. Chandra Sekhar Reddy, S. Sakthivel, “Development of cost-efficient solar receiver tube with a novel tandem absorber system”, Appl. Therm. Eng. 109 (2016) 988–996.
[15] D. Karthik, S. Pendse, S. Sakthivel, E. Ramasamy, S.V. Joshi, “High performance broad band antireflective coatings using a facile synthesis of ink-bottle mesoporous MgF2 nanoparticles for solar applications”, Sol. Energy Mater. Sol. Cells 159 (2017) 204–211.