Developing NaAc∙3H2O-based composite phase change material using glycine as temperature regulator and expanded graphite as supporting material for use in floor radiant heating

Abstract

Floor radiant heating embedded phase change materials (PCMs) are a prospective field owing to its highly efficient energy-saving effect and comfortable thermal environment. In this work, using a non-eutectic mixture comprised of NaAc∙3H2O (main PCM) and glycine (temperature regulator) as PCM, and expanded graphite (EG) as supporting material, a novel composite PCM with high thermal performance used in the heat exchanger for the floor radiant heating was developed. The composition of the composite PCM was optimized, and its properties were studied. The results showed that the mixture containing 12% glycine was favorable due to its suitable phase change temperature (48.62 °C) and high phase change enthalpy (258.5 kJ·kg−1). The addition of 12% EG into the mixture could enhance thermal conductivity and prevent leakage of the mixture simultaneously. The resulting composite PCM melted at 47.14 °C with phase change enthalpy of 214.7 kJ·kg−1, supercooling degree of 1.49 °C and thermal conductivity of 6.400 W m−1 K−1. The composite PCM also presented a good thermal reliability. Hence, the as-prepared composite PCM would be of great promise for use in the heat exchanger for the floor radiant heating. Besides, the present work is expected to provide a new pathway for exploring new types of PCMs.