Investigation of Caloric Materials for Cooling Application Based on MCE or ICE

Abstract

Over the past few decades, extensive efforts have been devoted to developing alternatives to the conventional vapor-compression refrigeration method that relies on gaseous refrigerants. Among these, one promising route is caloric effect-based refrigeration. The caloric effect refers to a phenomenon in which the temperature or entropy of a material changes when an external field is applied or removed. Depending on the type of applied field, the caloric effect can be categorized into several types, and its performance varies with the materials and operating temperature. Therefore, identifying suitable caloric materials for a given temperature range and environment is one of the central challenges in the field of caloric effect research In this paper, we report high-performance caloric materials for both the magnetocaloric effect (MCE), driven by a magnetic field, and the ionocaloric effect (ICE), driven by electrochemical potential. For cooling near hydrogen liquefaction temperatures, we evaluated the MCE and rotational magnetocaloric effect (RMCE) performance of Er0.7Tm0.3Al2 single crystals and TmGa textured polycrystals. Notably, the Er0.7Tm0.3Al2 single crystal exhibits maximum isothermal entropy change (∆𝑆𝑚) of 27.1 and 41.0 J kg⁄ K under field change of 20 and 50 kOe, respectively. Meanwhile, the TmGa textured polycrystal shows maximum isothermal rotational magnetic entropy change (∆𝑆r) of 17.2 and 24.3 J kg⁄ K at 20 and 50 kOe , respectively. Furthermore, we investigated the ICE performance of H2O for sub-zero temperature cooling. H2O exhibits a maximum isothermal entropy change (∆𝑆iso) of 1215 J kg⁄ K, and when NaI is utilized as the paired salt, it yields an adiabatic temperature change (∆𝑇ad) of up to 31.1 K. These values are in excellent agreement with experimental results obtained using a custom-built adiabatic chamber. Experiments with four different paired salts demonstrated that not only the caloric material but also the type of paired salt exerts a significant influence on ICE performance. In addition, to examine the practical applicability of ICE-based refrigeration using H2O, both the electrodialysis method and the heat distillation method were employed, and the coefficient of performance (COP) and cooling power of the respective systems were comparatively analyzed.