Experimental study of novel waste-based hybrid phase change materials: Synthesis and thermophysical properties

This work investigates the synthesis and thermophysical properties of novel hybrid phase change materials (PCMs), containing waste coconut oil, waste pork fat, and conventional PCM, i.e., paraffin RT26. Materials were examined as standalone PCMs and as hybrid binary PCMs that could serve as potential novel materials for thermal energy storage (TES). A comprehensive description of the sample preparation is provided, along with characterization of the mixtures with Fourier Transform Infrared Spectroscopy (FTIR). The resulting composites were assessed for physical stability, while their thermal properties, including latent heat, melting points, thermal conductivity, thermal diffusivity, volumetric specific heat capacity, and thermal stability were examined with Differential Scanning Calorimetry (DSC), Transient Hot Wire (THW) and Thermogravimetric analysis (TGA) techniques. Results revealed that incorporation of 20 wt% coconut oil and 20 wt% of pork fat into paraffin resulted in a decrease of its melting enthalpy by 6.54 % and 16.81 %, respectively. On the contrary, the thermal conductivity of paraffin increased by approximately 7 %, although the absolute value remained low (around 0.15 W m -1 K -1 ). The total cost per kilogram of the PCM was reduced by 9.43 % for the paraffin-based composite with 20 wt% of coconut oil, and 17.65 % for the composite with the same amount of pork fat. • Novel phase change composites made of paraffin RT26, waste coconut oil and pork fat • High enthalpy and favourable melting ranges identified for novel hybrid materials • Addition of waste oil and fat improved thermal conductivity of the paraffin • Novel phase change composites have lower cost and improved sustainability