Physically microencapsulated phase change materials for wide range of applicable temperatures

Abstract

The solid–liquid phase change thermal energy storage (TES) technique has attracted much interest, not only due to its high thermal energy density and conductivity, but also due to the recent increasing demand for thermal energy to achieve carbon neutrality. However, it is difficult to handle phase change materials (PCMs) during the processes of storage and release of thermal energy due to leakage and corrosion issues. Microencapsulation of PCMs is an emerging technology to solve these problems. Despite the advantages of microencapsulated PCMs, complex fabrication processes involving pH control with toxic chemicals, such as formaldehyde, have limited the mass productivity and environmentally friendly application of this technique. Herein, we report a physical microencapsulation solvent evaporation process that does not require complex process control. We successfully fabricated various PCM/polymethyl methacrylate microcapsules with various latent heat (144.13–217.70 J/g) and phase change temperatures (20–70 °C), and demonstrate that the proposed method can be applied to various organic-based PCMs for numerous applications. A composite polymer stack was fabricated by mixing high-density polyethylene (HDPE) with different PCM microcapsules and evaluated to determine the thermal properties of various samples for TES devices. In natural cooling tests, the composite showed a 56 % increase in cooling duration compared with the HDPE stack without PCM microcapsules. We expect that the proposed PCM microencapsulation process will significantly accelerate the development of PCM TES in industrial and residential fields.