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Faculty of Mechanical Engineering, Lj. (FSLJ)
  • Elastocaloric effect of Ni-Ti wire for application in a cooling device [Elektronski vir]
    Tušek, Jaka ...
    We report on the elastocaloric effect of a superelastic Ni-Ti wire to be used in a cooling device. Initially, each evaluated wire was subjected to 400 loading/unloading training cycles in order to ... stabilize its superelastic behavior. The wires were trained at different temperatures, which lead to different stabilized superelastic behaviors. The stabilized (trained) wires were further tested isothermally (at low strain-rate) and adiabatically (at high strain-rate) at different temperatures (from 312K to 342 K). We studied the impact of the training temperature and resulting superelastic behavior on the adiabatic temperature changes. The largest measured adiabatic temperature change during loading was 25K with a corresponding 21K change during unloading (at 322 K). A special focus was put on the irreversibilities in the adiabatic temperature changes between loading and unloading. It was shown that there are two sources of the temperature irreversibilities: the hysteresis (and related entropy generation) and the temporary residual strain immediately after unloading, respectively. The latter results in the temporary bending of the wire and reduced negative adiabatic temperature change. The paper also shows the impact of the applied strain on the adiabatic temperature changes as well as the distribution of the elastocaloric effect over the wire during loading in the case of two wires trained at different temperatures and the virgin wire, respectively. In the end, we propose guidelines about the required material properties for an efficient elastocaloric cooling device.
    Source: Journal of applied physics [Elektronski vir]. - ISSN 1089-7550 (Vol. 117, iss. 12, 2015, f. 1-11)
    Type of material - e-article
    Publish date - 2015
    Language - english
    COBISS.SI-ID - 14031387

    Link(s):

    http://scitation.aip.org/content/aip/journal/jap/117/12/10.1063/1.4913878
    DOI

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