Parametric analysis of fatigue-resistant elastocaloric regenerators : tensile vs. compressive loading

Ahčin, Žiga (author), Tušek, Jaka (author)

Elastocaloric cooling has recently shown high potential as an environmentally friendly alternative to vapor-compression technology. Here, we have studied and analyzed the geometric characteristics of two active elastocaloric regenerators (AeCRs) that were proved to have high application potential, i.e., a shell-and-tube AeCR loaded in compression and a parallel-plate AeCR loaded in tension, with the goal of maximizing their cooling performance. For this purpose, a previously developed and experimentally verified 1D numerical model was used. We focused only on the geometries and operating conditions that allow for durable, i.e., buckling-free operation in compression and fatigue-resistant operation in tension. The results show that although the applied strain of the parallel-plate AeCR loaded in tension needs to be limited (below 2%) to ensure fatigue-resistant operation, it outperforms (in terms of cooling power and COP at 15 K of temperature span) the shell-and-tube AeCR, which due to buckling issues suffers from a poorer heat-transfer geometry, but can withstand higher strains due to compressive loading. At the maximum strain of 2%, the optimum parallel-plate AeCR can generate a maximum cooling power of 1825 W (corresponding to 7075 W kg$^{−1}$ of elastocaloric material) and a COP of 9.15 at a zero-temperature span. On the other hand, due to a higher applied strain (3%) the optimum shell-and-tube AeCR can generate a higher maximum temperature span at zero cooling power (up to 50 K) but has limited cooling performance at lower temperature spans. In addition, the layering of the shell-and-tube AeCR was investigated for the first time to improve its performance. This study shows the crucial impact of the heat-transfer geometry (heat-transfer area and hydraulic diameter), which needs to be further improved in compression-loaded AeCRs to improve their efficiencies (without compromising the buckling stability). The study also shows the importance of the applied strain, which needs to be at least 2% or more to achieve a high cooling performance of the AeCR. The obtained results should serve as guidelines for designing powerful and efficient AeCRs in the future.

• Language: English
• Keywords: elastocaloric effect, caloric cooling, Ni-Ti, regenerators, parametric analysis
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FS - Faculty of Mechanical Engineering
• Publication status: Published
• Publication version: Version of Record
• Year: 2023
• Number of pages: 13 str.
• Numbering: Vol. 231, art. 120996
• PID: 20.500.12556/RUL-147390
• UDC: 519.876.5:621.57
• ISSN on article: 1359-4311
• DOI: 10.1016/j.applthermaleng.2023.120996
• COBISS.SI-ID: 157626371
• Publication date in RUL: 04.07.2023

Record is a part of a journal

• Title: Applied thermal engineering
• Shortened title: Appl. therm. eng.
• Publisher: Elsevier
• ISSN: 1359-4311
• COBISS.SI-ID: 1861910

Licences

• License: CC BY-NC-ND 4.0, Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
• Link: http://creativecommons.org/licenses/by-nc-nd/4.0/
• Description: The most restrictive Creative Commons license. This only allows people to download and share the work for no commercial gain and for no other purposes.

Secondary language

• Language: Slovenian
• Keywords: elastokalorični učinek, kalorično hlajenje, Ni-Ti, regeneratorji, parametrična analiza

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