Thermal Characterization of Paraffin-Based Phase Change Materials for Thermal Energy Storage and Improved Thermal Comfort

Urban densification intensifies urban heat islands (UHIs), leading to higher temperatures in cities which negatively affect residents’ health and comfort and increase energy consumption for air conditioning, thereby raising carbon emissions. Reducing UHIs is therefore essential. Phase change materials (PCMs) are a promising solution, as they can store and release significant amounts of thermal energy during phase transitions. Selecting paraffins with suitable properties is crucial for effective application. In this study, three paraffins (RT28HC, RT31, and RT35HC) with phase change temperatures of 28 °C, 31 °C, and 35 °C were characterized to evaluate their potential for summer UHI mitigation. Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and measurements of thermophysical properties and density were performed. Results showed that RT28HC and RT35HC exhibit relatively simple and efficient phase transitions, while RT31 has a more complex mechanism with a wide phase change temperature range. During limited summer day–night temperature variations, RT31 may not fully crystallize, reducing the effective utilization of stored energy. These findings highlight the importance of selecting paraffins with appropriate phase change temperatures and thermal properties to optimize the performance of PCMs for urban heat mitigation.