Abstract
Despite the challenges of practical implementation, electrocaloric (EC) cooling remains a promising technology because of its good scalability and high efficiency. Here, we investigate the feasibility of an EC cooling device that couples the EC and electromechanical (EM) responses of a highly functionally, efficient, lead magnesium niobate ceramic material. We fabricated multifunctional cantilevers from this material and characterized their electrical, EM and EC properties. Two active cantilevers were stacked in a cascade structure, forming a proof-of-concept device, which was then analyzed in detail. The cooling effect was lower than the EC effect of the material itself, mainly due to the poor solid-to-solid heat transfer. However, we show that the use of ethylene glycol in the thermal contact area can significantly reduce the contact resistance, thereby improving the heat transfer. Although this solution is most likely impractical from the design point of view, the results clearly show that in this and similar cooling devices, a non-destructive, surface-modification method, with the same effectiveness as that of ethylene glycol, will have to be developed to reduce the thermal contact resistance. We hope this study will motivate the further development of multifunctional cooling devices.
Highlights
The electrocaloric (EC) effect is the electric-field-induced temperature change in polar materials
In this work we have fabricated, characterized and analysed PMN-based unimorph cantilevers consisting of PMN/Pt/PMN layers. Such cantilevers are an essential building block of the cooling device designed here that exploits the multifunctional nature of PMN, i.e., the electromechanical (EM) and electrocaloric (EC) functionality, to enable concurrent thermal contacts by EM bending and the cooling capability based on the EC effect
The PMN/Pt/PMN cantilever structure exhibited lower polarization values in comparison to their bulk counterparts for the same applied electric field, which was ascribed to the different conditions for the preparation of the samples and the effect of the inactive PMN layer in the cantilever’s structure
Summary
The electrocaloric (EC) effect is the electric-field-induced temperature change in polar materials. PST exhibits a high EC response for two main reasons: (i) the thick-film form allows a relatively high electric field to be applied to the material without causing a break-down [7]; and (ii) the relaxor ferroelectric nature of PST enables a high EC effect due to the absence of the ferroelectric long-range order, resulting in large entropy changes with the applied electric field. The area of the hysteresis is related to the electrical losses in the materials [11,12,13,14], where the losses are manifested as an increase in the temperature during field cycling and are detrimental to the EC cooling [15]. For the successful implementation of EC cooling, such losses must be minimized [16]
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.
