Thermal storage performance enhancement and regulation mechanism of KNO3-SWCNT based composite phase change materials

Abstract

In this paper, the single walled carbon nanotube (SWCNT) was doped into KNO3 to prepare the KNO3-SWCNT based composite phase change material (CPCM), and its microstructure was established. The methods of thermal storage performance prediction, enhancement and regulation for CPCM were developed by means of molecular dynamics (MD) simulation combined with experiments, and the microscopic mechanism was revealed at nanoscale. It was found that when SWCNT mass fraction increases from 0 to 4.43 wt. % and 8.48 wt. %, the thermal conductivity is significantly increased, with an average increase of 2.26% and 28.01%, respectively, the specific heat capacity is effectively enhanced by 11.72% and 16.55%, respectively, and the melting enthalpy is decreased by 32.31% and 45.19%, respectively. The SEM experiments are carried out to characterize the microstructure of CPCM, inspired by the ordered distribution of SWCNT, the formation of thermal link and nano layer in CPCM can be promoted, so as to improve the thermal storage performance of CPCM; the interface regulation was achieved by the surface positive modification of SWCNT, which can effectively enhance the potential energy interaction between the atoms, thus the thermal conductivity of CPCM is enhanced, with an average enhancement of 21.21%.