From the elastocaloric effect towards an efficient thermodynamic cycle

Kabirifar, Parham (author), Trojer, Jonas (author), Brojan, Miha (author), Tušek, Jaka (author)

In recent years, the elastocaloric cooling technology has been considered as one of the most promising alternatives to the vapor compression technology. Given that the elastocaloric technology is only in the early stage of development, a uniform method for evaluating the elastocaloric effect has not yet been established and the thermodynamics of different elastocaloric cooling cycles have not yet been studied in detail. Therefore, the main goal of this work is to investigate these two important areas. Here, multiple thermodynamic cycles were studied, focusing on the parameters of the holding period of the cycle, which is essential for heat transfer between the elastocaloric material and the heat sink/source. The cycles were applied to commercially available superelastic thin-walled NiTi tubes under compressive loading and a thin NiTi wire under tensile loading. Isostress cycles with constant stress throughout the holding period, isostrain cycles with constant strain throughout the holding period and no-hold cycles (without a holding period) were studied across multiple stress/strain range. Based on the experimental results, a previously developed phenomenological model was applied to better understand and further evaluate the different cycles. The results revealed that the applied thermodynamic cycle significantly affects the thermomechanical response and thus the cooling/heating efficiency of the elastocaloric material. We show that by using the isostress cycles and partial transformation, a Carnot-like thermodynamic cycle with improved heating/cooling efficiency can be generated. By applying the isostress cycles, an adiabatic temperature change of 30.2 K was measured, which is among the largest directly measured reproducible adiabatic temperature changes reported for any caloric material to date. Ultimately, this study intends to serve as a basis for establishing a uniform method for evaluating the elastocaloric effect in different materials that would allow for reliable and accurate one-to-one comparison of the reported results in the rapidly growing field of elastocalorics.

• Language: English
• Keywords: elastocaloric effect, shape memory alloys, thermodynamic cycle, Carnot, Brayton, efficiency, phenomenological modeling
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FS - Faculty of Mechanical Engineering
• Publication status: Published
• Publication version: Version of Record
• Year: 2022
• Number of pages: 22 str.
• Numbering: Vol. 4, no. 4, art. 044009
• PID: 20.500.12556/RUL-142646
• UDC: 539.3
• ISSN on article: 2515-7655
• DOI: 10.1088/2515-7655/ac92a5
• COBISS.SI-ID: 122613251
• Publication date in RUL: 17.11.2022

Record is a part of a journal

• Title: JPhys energy
• Shortened title: JPhys energy
• Publisher: IOP Publishing
• ISSN: 2515-7655
• COBISS.SI-ID: 529763609

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: elastokalorični učinek, zlitine z oblikovnim spominom, termodinamični cikel, Carnot, Brayton, učinkovitost

Projects

• Funder: EC - European Commission
• Funding programme: H2020
• Project number: 803669
• Name: Superelastic Porous Structures for Efficient Elastocaloric Cooling
• Acronym: SUPERCOOL

• Funder: ARRS - Slovenian Research Agency
• Project number: P2-0422
• Name: Funkcionalne tekočine za napredne energetske sisteme