▎ 摘　　要

Utilization of phase change material (PCM) for air conditioner application is very important to save excessive electricity consumption. RT 22 HC has been used in cold storage applications because of its suitable melting point. Graphene nano platelets were used as nano particles to increase the thermal conductivity of RT 22 HC. The thermal stability of RT 22 HC/graphene has been tested up to 1000 cycles, and a cycle test apparatus has been designed for PCM. The objective of this study is to characterize the thermal stability of RT 22 HC/Graphene using a thermoelectrically based thermal cycle test method. PCM and nano-PCM tests prior to cycle thermal testing measured the morphology and microstructure, chemical structure, latent heat, melting point, freezing point and specific heat capacity, thermal conductivity, and viscosity. The mass fractions of Nano-PCMs were 0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, respectively. The result showed that the latent heat of fusion and solidification as well as the melting and freezing points changed little and were not significant with the addition of graphene to RT 22 HC. However, the effect of adding nano graphene increases the thermal conductivity to 89.6%. In this study, a new method for testing the thermal stability of PCM was also developed and based on thermoelectrical cycle test equipment. In this study, it was found that the latent heat of fusion and melting point of RT 22 HC (melting and freezing) did not change significantly after 1000 cycles. Moreover, the chemical formation of RT 22 HC/graphene was not affected after a high number of repeated cycles. (C) 2017 Elsevier Ltd. All rights reserved.