Properties of n-Octadecane PCM Composite with Recycled Aluminum as a Thermal Enhancer

This paper presents new types of PCM composites proposed and analyzed for cooling applications in buildings. The composites (n-octadecane-Al-long/n-octadecane-Al-short) were made of n-octadecane with 7% and 7.5% vol. of recycled aluminum added as a thermal conductivity enhancer to avoid sinking during the melting phase and to improve thermal conductivity. Recycled aluminum chips are inexpensive, abundant, and generate a lower environmental impact during composite production. The effect of the chip content was found to increase the thermal conductivity values of the composites by 100% (n-octadecane-Al short) and by 600% (n-octadecane-Al-long) compared to n-octadecane. The percentage of mass increase remained low. The latent heat of n-octadecane-Al-long decreased from 245 kJ/kg to 195 kJ/kg, the melting time shortened from 990 s to 850 s, and the CO2 emission reduction was by 150 kg CO2eq/year. The volume of the PCM composites varied from 0.083 m3 (n-octadecane) to 0.091 for n-octadecane-Al-long, which represents an increase of up to 11% needed to absorb the solar heat gained by the optimized PCM composite.