Effects of Supercooling Degree and Specimen Size on Supercooling Duration of Erythritol

The duration of supercooling for erythritol, a promising phase change material with a melting point of 118 degrees C, was investigated in a glass tube using three small specimen volumes of 0.025, 0.40, and 16.0 cm(3) in glass tube diameters of 1.02, 10.0, and 27.3 mm, respectively. The supercooling duration was measured by the temperature increase of the specimen due to the release of latent heat under a constant degree of supercooling from 38 to 98 degrees C. The supercooling duration was largely dependent on the supercooling degree and specimen sizes, and increased from approximately 0.1 to 20 000 min with a decrease in the supercooling degree and specimen size. The effects of the supercooling degree and specimen size on the supercooling duration are discussed in terms of the Johnson-Mehl-Avrami equation and three nucleation theories based on the observed solidification position; homogeneous nucleation, heterogeneous nucleation from the wall, and heterogeneous nucleation from insoluble particles.