Recycled Aluminum Paraffin Composite for Passive Cooling Application in Buildings

This paper presents a new composite phase change material made of paraffin and recycled aluminum sawing chips. Aluminum sawing chips were selected as a thermal conductivity enhancer, the volume fraction (~15%) of which, in the paraffin composite material, was minimized by selecting a fraction with shape that minimizes its packing density. Therefore, the particles remained in contact inside the composite, and thus, their sinking in the liquid state was avoided. The paraffin composite obtained had a latent heat capacity reduced by 20% compared to the paraffin and the thermal conductivity increased by 236%. The composite materials also had a wide active temperature range (33–65 °C). Incorporation of this paraffin composite in the brick cavities was tested as a way of improving the heat transfer fluctuations in the hot hours of the day. The experimental data show a maximum temperature difference of about 3 °C in comparison with bricks without the paraffin composite incorporated. To evaluate the environmental impact of the paraffin composite, the Global Warming Potential (CO2eq) was determined. The results highlighted less CO2eq in comparison with other recycled composite materials.