Experimental investigation of phase change materials fabricated using selective laser sintering additive manufacturing

Abstract The increased demand for phase-change-materials-enabled energy storage systems exposed the limitations of established manufacturing methods in terms of material properties, fabrication speed, material waste, and shape-form flexibility. Phase change materials have unique merits in latent heat thermal energy storage, due to its capability of providing high-energy density storage by solidifying/melting at a constant temperature. In this research, a phase change composite was developed by mixing paraffin wax with a thermal conductive expanded graphite. Using a layer-by-layer laser sintering method, these two materials were combined at a micro-scale, forming a phase change composite that possesses good thermal conductivity, superior latent heat, and good mechanical strength. This work investigated the key parameters for successful production of paraffin wax/expanded graphite composite using laser sintering technique. In particular, the paraffin wax is melted and then impregnated into the inter-particle pores of expanded graphite through capillaries. It serves as a binder that bonds the expanded graphite molecules together into a solid form-stable object during the laser sintering process. To validate the developed sintering process, samples with a various number of layers were fabricated and tested. Results showed good structural integrity and functionality of the printed samples. The thermal conductivity was in the range of 0.83–0.92 W m−1 K−1. The latent heat was in the range of 150–156 kJ kg−1. Modulus of elasticity was between 808–880 MPa while the tensile strength in the range of 2.2–3.3 MPa. The electrical resistivity ranged between 8 and 28 Ohm m. These experimental results verified that the developed laser sintering process could be used as an effective nontraditional manufacturing technique for fabricating phase change materials for thermal energy storage applications.