10:15 AM - 10:30 AM
[MIS13-05] In-situ observation of the crystal growth process of latent heat storage material erythritol
Keywords:heat storage material, erythritol, in-situ observation
Erythritol is one of the promising candidate materials for heat storage due to its high latent heat, stability and safety characteristics. Its melting temperature of 393 K makes it particularly suitable for storing west heat energy from the industrial processes.
Despite these advantageous properties, erythritol exhibits significant undercooling during solidification that makes precise control of its operating temperature challenging. To understand the solidification behavior, we have conducted the in-situ observations of crystal growth process of erythritol in undercooled region.
Erythritol was placed on a glass slide with a circular cavity (diameter: 15 mm, depth: 0.6 mm) and heated above its melting temperature until fully molten. Then the molten erythritol was transferred to another heater set to specific undercooling temperature. Once a stable undercooled state was achieved, heterogeneous nucleation was induced by inserting a silver wire maintained at the same temperature as the erythritol. The subsequent crystal growth process was observed in situ using a stereo microscope.
At the undercoolings below 20 K, erythritol exhibited faceted growth with maintaining with smooth interfaces. In the undercooling range of 30 - 40 K, dendritic growth was observed, while undercoolings above 50 K, growth morphology transitioned to a spherulite morphology. As undercooling increased, the growth rates along (100) and <110> increased up to 60 K, but then became constant or slightly decrease at higher undercooling.
The critical nucleus radius, estimated from the dendrite tip curvature, decreased with increasing undercooling up to 60 K and then remained constant. These findings suggest that at bulk undercooling exceeding 60 K, the release of large latent heat during crystallization maintains a constant at the crystal-liquid interface.
Despite these advantageous properties, erythritol exhibits significant undercooling during solidification that makes precise control of its operating temperature challenging. To understand the solidification behavior, we have conducted the in-situ observations of crystal growth process of erythritol in undercooled region.
Erythritol was placed on a glass slide with a circular cavity (diameter: 15 mm, depth: 0.6 mm) and heated above its melting temperature until fully molten. Then the molten erythritol was transferred to another heater set to specific undercooling temperature. Once a stable undercooled state was achieved, heterogeneous nucleation was induced by inserting a silver wire maintained at the same temperature as the erythritol. The subsequent crystal growth process was observed in situ using a stereo microscope.
At the undercoolings below 20 K, erythritol exhibited faceted growth with maintaining with smooth interfaces. In the undercooling range of 30 - 40 K, dendritic growth was observed, while undercoolings above 50 K, growth morphology transitioned to a spherulite morphology. As undercooling increased, the growth rates along (100) and <110> increased up to 60 K, but then became constant or slightly decrease at higher undercooling.
The critical nucleus radius, estimated from the dendrite tip curvature, decreased with increasing undercooling up to 60 K and then remained constant. These findings suggest that at bulk undercooling exceeding 60 K, the release of large latent heat during crystallization maintains a constant at the crystal-liquid interface.