Analysis on phase transition range of the pure and mixed phase change materials (PCM) using a thermostatic chamber test and differentiation

A phase change material (PCM) is a type of thermal storage material. The thermal performance of PCMs is evaluated by latent heat capacity and phase change temperature range. The phase change temperature of the phase change materials (PCM) is a critical factor in selecting a PCM. In this study, the conditions of physical and chemical bonding of PCMs including n-octadecane, n-docosane, palm wax, and two types of mixed PCMs were analyzed using the differential scanning calorimetry and the Fourier transform infrared. The phase change temperature range of these PCMs were analyzed using a thermostatic chamber test. In addition, the analysis method of the phase transition range of these PCMs was studied using the first and second derivatives. As a result, the phase changes of n-octadecane, n-docosane, and palm wax occurred at 27, 43, and 45–62 °C, respectively. It is not possible to determine the exact temperature at which phase change occurs with palm wax because palm wax includes various acids. Also, the results of the mixed PCM of n-octadecane and palm wax indicate several peaks. Finally, through a second derivative, it proved that the mixed PCM of n-octadecane and palm wax melts at 18.3–29.1 and 35.1–42.9 °C and freezes at 48.4–51.8, 31.8–34.1, and 23.7–26.9 °C.