An efficiency improvement of concentrating solar power systems relies on a significant increase of the operating temperatures, exceeding 600 °C. This goal can be achieved through the use of solar absorbers possessing high spectral selectivity and stability at such temperatures. Suitable alternatives to the largely used silicon carbide can be found in the ultra-high temperature ceramics class. This study focuses on the effect of processing, microstructure evolution and surface texture on the optical properties at room and high temperature. ZrB 2 -based ceramics are taken as case study to detect any correlation amongst composition, porosity, mean grain size, roughness and spectral selectivity. In addition, the effect of surface variation, induced by chemical etching or by exposure to oxidizing environment, thus simulating the actual operation conditions, are evaluated and compared to SiC optical properties. Absorbance and solar selectivity are discussed as a function of the microstructural and surface properties upon detailed roughness characterization. Advantages in the use of UHTCs as solar absorbers, strength and criticalities related to the use of these ceramics in comparison with SiC are discussed.

An overview of ultra-refractory ceramics for thermodynamic solar energy generation at high temperature

Orrù, Roberto;Licheri, Roberta;Musa, Clara;
2019-01-01

Abstract

An efficiency improvement of concentrating solar power systems relies on a significant increase of the operating temperatures, exceeding 600 °C. This goal can be achieved through the use of solar absorbers possessing high spectral selectivity and stability at such temperatures. Suitable alternatives to the largely used silicon carbide can be found in the ultra-high temperature ceramics class. This study focuses on the effect of processing, microstructure evolution and surface texture on the optical properties at room and high temperature. ZrB 2 -based ceramics are taken as case study to detect any correlation amongst composition, porosity, mean grain size, roughness and spectral selectivity. In addition, the effect of surface variation, induced by chemical etching or by exposure to oxidizing environment, thus simulating the actual operation conditions, are evaluated and compared to SiC optical properties. Absorbance and solar selectivity are discussed as a function of the microstructural and surface properties upon detailed roughness characterization. Advantages in the use of UHTCs as solar absorbers, strength and criticalities related to the use of these ceramics in comparison with SiC are discussed.
2019
Ageing; Concentrating solar power; Optical properties; Solar absorbers; Ultra-high temperature ceramics; ZrB 2; Renewable Energy, Sustainability and the Environment
File in questo prodotto:
File Dimensione Formato  
Silvestroni_et_al_accepted.pdf

Open Access dal 11/08/2020

Descrizione: Verisione accettata
Tipologia: versione post-print
Dimensione 3.03 MB
Formato Adobe PDF
3.03 MB Adobe PDF Visualizza/Apri
An overview of ultra-refractory ceramics for thermodynamic solar energy generation at high temperature.pdf

Solo gestori archivio

Descrizione: articolo
Tipologia: versione editoriale
Dimensione 4.39 MB
Formato Adobe PDF
4.39 MB Adobe PDF   Visualizza/Apri   Richiedi una copia

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11584/262249
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 34
  • ???jsp.display-item.citation.isi??? 29
social impact