Thermal Performance Evaluation of Encapsulated Phase Change Materials Exposed to Contact Heat and Radiant Heat

This article describes research on two encapsulated phase change materials (PCMs) from the alkane group (n-hexadecane and n-octadecane) with phase transition temperatures of 18.2 °C and 28.2 °C, respectively. The main goal of the study was to determine the internal structure and basic thermal properties of both types of macrocapsules in terms of their potential applications. The internal structure of the macrocapsules was characterized using non-destructive statistical quantitative analysis performed using X-ray microtomography (micro-CT). Differential scanning calorimetry (DSC) was used to determine the phase transition temperatures, thermal cycling stability, and phase transition enthalpies of both PCMs. The macrocapsules were tested in two experiments, simulating the conditions of their potential application by exposing them to contact heat and radiant heat. Structural analysis showed that the macrocapsules differ significantly in PCM content (77% n-hexadecane and 88% n-octadecane) and porosity (19% and 10%, respectively). According to the DSC results, the macrocapsules with n-octadecane exhibited a significantly wider phase transition range and a greater ability to store latent heat indicated by its higher enthalpy by about 30 J·g^-1 than those with n-hexadecane. The results of experiments involving PCM exposure to contact heat and radiant heat demonstrated the potential applications of the macrocapsules in thermal packaging, building, and protective clothing.