Form-stable LiNO3-NaNO3-KNO3-Ca(NO3)2/calcium silicate composite phase change material (PCM) for mid-low temperature thermal energy storage

In this paper, a novel form-stable LiNO3-NaNO3-KNO3-Ca(NO3)(2)/calcium silicate composite PCM was developed by cold compression and sintering. The eutectic quaternary nitrate is used as PCM, while calcium silicate is used as structural supporting material. X-ray Diffraction (XRD) shows the PCM and the supporting material have good chemical compatibility. This composite PCM has a low melting point (103.5 degrees C) and remain stable without decomposition until 585.5 degrees C. Moreover, this composite shows excellent long term stability after 1000 melting and freezing cycles. Thermal conductivity of the composite was measured to be 1.177 W m(-1) K-1, and that could be increased by adding thermal conductivity enhancers into the composite. Meanwhile, microstructure of the composite PCM is observed by scanning electron microscopy (SEM). Latent heat and heat capacity of the composite are measured by differential scanning calorimetry (DSC). This composite PCM with low melting temperature, high thermal conductivity and excellent stability could be used as a new PCM for mid-low temperature thermal energy storage (TES) system. (C) 2015 Elsevier Ltd. All rights reserved.