Preparation and thermal properties of NaOAc•3H2O-CO(NH2)2 non-eutectic binary mixture PCM for radiant floor heating system

To make full use of phase change material (PCM) in heat exchanger for radiant floor heating system, the NaOAc.3H(2)O-CO(NH2)(2) non-eutectic binary mixture PCM, using NaOAc.3H(2)O as phase change principal component, CO(NH2)(2) as temperature regulator and Na2HPO4.12H(2)O as nucleator as well as sucrose (C12H22O11) as auxiliary nucleator, was developed. The possible thermoregulation mechanism of CO(NH2)(2) on NaOAc.3H(2)O was preliminarily discussed. Meanwhile, the supercooling degrees of the non-eutectic PCMs with different Na2HPO4.12H(2)O and C12H22O11 contents were also investigated. The results showed that the NaOAc.3H(2)O-CO(NH2)(2) non-eutectic binary mixture PCM containing 8% CO(NH2)(2), 1.5% Na2HPO4.12H(2)O and 2% C12H22O11 possessed a proper phase change temperature (48.45 degrees C), high latent heat (245.4 J/g), the low supercooling degree (2.60 degrees C), the enhanced crystallization behavior and an excellent thermal reliability. The hydrogen-bond interactions of -NH2 in CO(NH2)(2) on three crystal H2O molecules and CH3COO- in NaOAc.3H(2)O weakened the intermolecular forces of NaOAc.3H(2)O and the coordination of NaOAc on H2O, thus resulting in a decrease in the phase change temperature of the non-eutectic mixture.