Title: High-efficiency, air-stable manganese–iron oxide nanoparticle-pigmented solar selective absorber coatings toward concentrating solar power systems operating at 750 °C

Abstract

Solar selective absorber coating with long-term thermal stability at high temperatures ≥750 °C in air is an important component to reduce the levelized cost of energy (LCOE) of concentrating solar power (CSP) systems toward 50% power efficiency and dispatchable solar electricity. Conventionally, solar spectral selectivity requires multilayer-interference coatings implemented by stringently controlled vacuum deposition, and these coatings degrade significantly at >700 °C in air. Herein, we established a quantitative design approach and demonstrated a proof-of-concept air-stable, manganese–iron oxide nanoparticle (NP)-pigmented solar selective coatings with a high solar absorptance of ~93%, a relatively low thermal emittance of ~52%, and an optical-to-thermal energy conversion efficiency >89% under 1,000× solar concentration at 750 °C toward Generation 3 CSP systems. These coatings demonstrate spectral selectivity using cost-effective spray coating approach, a notable improvement over conventional vacuum-deposited, multilayer solar selective coatings for low-cost, high-efficiency solar thermal receivers. In contrast to the thermal degradation of spectrally non-selective benchmark Pyromark 2500 coatings at 750 °C in air, the solar absorptance of the MnFe₂O₄-pigmented coatings on stainless steel 310 (SS 310) substrates is increased to ~92.9% and the optical-to-thermal energy conversion efficiency is improved to 89.7% after serving at 750 °C in air for 700 h. X-ray diffractionmore » results reveal that this improvement is due to the transformation of MnFe₂O₄ NPs into more thermodynamically stable, non-stoichiometric manganese-rich manganese ferrite and iron-rich manganese–iron oxide phases after 500 h aging at 750 °C. For >1,000 h-endurance testing at 750 °C in air and the subsequent 19 day-night thermal cycling between 750 °C (12 h/cycle) and 25 °C (12 h/cycle) on SS 310 substrates, the thermal degradation is mainly due to the CrO_x microflake formation from SS 310 substrates rather than the coatings, which can be suppressed by preoxidizing the surface of SS 310. With lower emittance matrix material and further optimization of pigment NP stoichiometry, concentration, and coating thickness, it is promising to achieve an optimized thermal efficiency ≥92.5% with long-term thermal stability at 750 °C for Generation 3 CSP systems.« less

Authors:

Wang, X. ^[1]; Lee, E. ^[1]; Xu, C.  ^[1];

• Search DOE PAGES for author "Xu, C."
• Search DOE PAGES for ORCID "0000-0001-5306-5367"

Liu, J.  ^[1]

• Search DOE PAGES for author "Liu, J."
• Search DOE PAGES for ORCID "0000-0003-4379-2928"

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+ Show Author Affiliations

1. Dartmouth College, Hanover, NH (United States). Thayer School of Engineering

Publication Date:

Wed Dec 02 00:00:00 EST 2020

Research Org.:

Dartmouth College, Hanover, NH (United States)

Sponsoring Org.:

USDOE Office of Energy Efficiency and Renewable Energy (EERE)

OSTI Identifier:

1848490

Alternate Identifier(s):

OSTI ID: 1781471

Grant/Contract Number:  

EE0007112; EE0008530

Resource Type:

Accepted Manuscript

Journal Name:

Materials Today Energy

Additional Journal Information:

Journal Volume: 19; Journal Issue: C; Journal ID: ISSN 2468-6069

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 36 MATERIALS SCIENCE; 14 SOLAR ENERGY; Chemistry; Energy & Fuels; Materials Science; Solar energy; High-temperature thermal stability; Manganese ferrite nanoparticles; Four-flux radiative method