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Published on: June 9, 2016
A Highly Stable and Sustainable Low-Temperature Selective Absorber: Structural and Ageing Characterisation
Meryem Farchado1, Gema San Vicente1, Nuria Germán1
1Unidad de Materiales para Tecnologías Termosolares de Concentración, Plataforma Solar de Almería, Departamento de Energía, Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT), Avda. Complutense 40, 28040 Madrid, Spain.
This study developed a durable three-layer solar absorber with high solar absorptance (>0.950) and low thermal emittance (<0.04). The selective absorber shows excellent stability and humidity resistance for solar thermal applications.
Area of Science:
- Materials Science
- Renewable Energy Engineering
- Surface Science
Background:
- Developing efficient and durable solar absorbers is crucial for advancing solar thermal technologies.
- Current selective solar absorbers face challenges in long-term stability and performance under harsh environmental conditions.
Purpose of the Study:
- To prepare and characterize a novel three-layer solar absorber with enhanced optical properties and durability.
- To investigate the impact of silica layer sintering conditions on the absorber's performance and longevity.
- To evaluate the protective mechanisms of the multi-layer structure against environmental degradation.
Main Methods:
- Fabrication of a three-layer solar absorber (two spinel layers, one silica layer) via dip-coating on aluminum substrates.
- Optimization of upper silica layer sintering conditions.
- Optical property measurements (solar absorptance, thermal emittance).
- Accelerated aging tests (thermal stability, condensation/humidity resistance).
- Material characterization using X-ray diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS).
Main Results:
- Achieved high solar absorptance (>0.950) and low thermal emittance (<0.04).
- Demonstrated excellent thermal stability and superior humidity resistance through accelerated aging tests.
- Identified protective roles of both the silica and underlying alumina layers in enhancing durability.
- Confirmed the presence of spinel-like phases in the absorber layers via XRD and XPS.
Conclusions:
- The proposed three-layer solar absorber exhibits exceptional optical performance and remarkable durability.
- The combination of silica and alumina layers provides effective protection against environmental degradation.
- The developed selective absorber demonstrates significant potential for low-temperature solar thermal applications.
