Abstract
Ceramic particles based packed bed systems are attracting the interesting from various high-temperature applications such as thermal energy storage, nuclear cooling reactors, and catalytic support structures. Considering that these systems work above 600 °C, thermal radiation becomes significant or even the major heat transfer mechanism. The use of coatings with different thermal and optical properties could represent a way to tune and enhance the thermodynamic performances of the packed bed systems. In this study, the thermal stability of several metallic (Inconel, Nitinol, and Stainless Steel) based coatings is investigated at both high temperature and cyclic thermal conditions. Consequently, the optical properties and their temperature dependence are measured. The results show that both Nitinol and Stainless Steel coatings have excellent thermal stability at temperature as high as 1000 °C and after multiple thermal cycles. Contrarily, Inconel (particularly 625) based coatings shows abundant coating degradation. The investigated coatings also offer a wide range of thermal emissivity (between 0.6 and 0.9 in the temperature range of 400–1000 °C), and variable trends against increasing temperature. This work is a stepping-stone towards further detailed experimental and modelling studies on the heat transfer enhancement in different ceramic-based packed bed applications through using metallic coatings. • Thermal stability of nine metallic coatings on ceramics is tested up to 1000 °C. • Inconel 738 shows excellent thermal stability after long residency at 1000 °C. • Nitinol and Stainless Steel 304 present oxidation but not coating loss under cycles. • Thermal emissivity are between 0.6 and 0.9 in the temperature range of 400–1000 °C. • Effective thermal conductivity increases of 17% at 1000 °C can be attained.
Highlights
Ceramic-based packed bed modules are currently widely used and under development as high-temperature sensible energy storage [1,2], gas cooled nuclear reactors [3,4], as well as catalytic reactors and sup port devices in the chemical field [5,6]
The IN based samples and the Nit powder shows high degree of material uniformity, a single material can be identified in the images
Nit sample shows a high degree of particle sphericity and particle diameter smaller than 80 μm
Summary
Ceramic-based packed bed modules are currently widely used and under development as high-temperature sensible energy storage [1,2], gas cooled nuclear reactors [3,4], as well as catalytic reactors and sup port devices in the chemical field [5,6]. A widely exploited method to control and modify the radiative heat transfer in high temperature application is to tune the surface optical properties by applying specific coatings [10]. Pyromark 2500 has been exploited in different commercial units [13], while experimental research has been performed on metal oxides, lanthanum strontium manganite (LSM) oxide, cobalt oxide, and refractory metal silicides [14]. These coatings ensure elevated solar absorptivity and thermal conductivity, limited thermal emissivity and thermo-chemical stability in open air environments above 600 ◦C [14], and could lead to re ductions of the levelized cost of electricity for CSP plants [15]. High temperature black paint (made of a poly phenylsiloxane binder and a metal oxide pigment), optical solar re flectors and second surface mirror type solar reflectors, and polysiloxane
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
