Simultaneous enhancement in thermal conductivity and heat storage capability of hexadecylamine/SiO2 for thermal energy storage

Abstract

Hexadecylamine (HDA) was encapsulated into SiO2 nano-shell to enhance the heat transfer rate without deteriorating the heat storage capability by a simple, environmentally benign, and cost-effective method. The investigation on the thermal properties of HDA/SiO2 ss-CPCM demonstrated that a good trade-off between latent heat capability and thermal conductivity increment was achieved. The SiO2 shell promoted the thermal conductivity and hence increased the heat transfer rate. The heat transfer rate of HDA/SiO2 ss-CPCM was enhanced during both the heating and cooling processes. It took 554 s and 454 s for the composite to vary from 40 °C to 78 °C and from 78 °C to 40 °C, <659 s and 538 s for the pure HDA. Its thermal conductivity (0.2304 W m−1 K−1) is about 200 % of that of the pristine HDA when modified with 5.1 wt% SiO2. Besides, the composite achieved an exciting latent heat capacity with a crystallization enthalpy of 210.8 J g−1 and a melting enthalpy of 214.9 J g−1. The values were a good approximation to those of pristine HDA (227.6 J g−1 and 224.3 J g−1). It also illustrated excellent thermal stability and reliability after undergoing 100 heating/cooling cycles. HDA/SiO2 ss-CPCM with good thermal properties can be applied in the field of thermal energy storage.