A High-Temperature Solar Selective Absorber Based upon Periodic Shallow Microstructures Coated by Multi-Layers Using Atomic Layer Deposition

Makoto Shimizu,Hiroo Yugami,Fumitada Iguchi,Hiroki Akutsu,Shinichiro Tsuda

doi:10.3390/photonics3020013

Abstract

Regarding the fabrication of solar selective absorbers, the ability to create microstructures on top of metal surfaces is a promising technology. Typically, these materials are able to possess spectrally-selective absorption properties for high-temperature usage. Solar-selective absorbers that function at temperatures up to 700 °C and possess shallow honeycomb cylindrical microcavities coated with a metal-dielectric multi-layer have been investigated. Honeycomb array cylindrical microcavities were fabricated on W substrate with interference lithography and multi-layers consisting of Pt nano-film sandwiched by Al2O3 layers were created for a uniform coating via atomic layer deposition. The absorbance spectrum of fabricated samples reveals results consistent with a simulation based on a rigorous coupled-wave analysis method. A solar absorbance value of 0.92 and a hemispherical total emittance value of 0.18 at 700 °C was determined from the fabricated solar-selective absorber. Additionally, thermal stability of up to 700 °C was confirmed in vacuum.

Highlights

In the present environmental situation, effective use of solar energy is very important
Solar photovoltaics are a popular topic within the energy community, yet solar thermal energy utilization has recently become prominent in the field of power generation and thermochemical conversion
Surface microstructures fabricated on refractory metals are a promising technology to control

Summary

Introduction

In the present environmental situation, effective use of solar energy is very important. Solar photovoltaics are a popular topic within the energy community, yet solar thermal energy utilization has recently become prominent in the field of power generation and thermochemical conversion. In these systems, the operating temperature has shifted towards high temperatures due to the efficient process of reaching larger temperatures. In concentrating solar power generation systems (CSP) with parabolic trough mirrors, the operating temperature range was formerly approximately 300 to 400 ̋ C [1,2,3]. In CSPs, steam turbines are applied to convert thermal energy into electricity. In terms of the cost, steam turbines are typically operated at approximately 600 ̋ C [5,6]

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