A novel microencapsulated medium-temperature phase change material employing dicarboxylic acid for thermal energy storage

•Microencapsulated glutaric acid (MEGA) was synthesized by sol–gel method.•Improved encapsulation ratio was achieved for the MEGA.•Thermal reliability index of MEGA was 94.4% after 200 thermal cycles.•MEGA suspensions exhibited improved thermal conductivity.•MEGA suspensions demonstrated reduced pumping power requirements. Microencapsulation enhances the performance of phase change materials (PCMs). However, the existing research on microencapsulation of dicarboxylic acids (DAs) is inadequate, with only one study dedicated to the development of microcapsules containing a low DA content and a shell that decomposes at low temperatures. In this study, glutaric acid (GA), as a representation of DA, was successfully microencapsulated with an enhanced encapsulation ratio. The results obtained by scanning electron microscopy (SEM) revealed a uniform spherical core–shell structure of the microencapsulated GA (MEGA). Fourier transform infrared spectroscopy (FT-IR) an X-ray diffractometer (XRD) analysis confirmed the absence of any chemical reaction between the core and shell materials. Additionally, differential scanning calorimetry (DSC) results demonstrated excellent heat storage. Notably, MEGA exhibited a thermal reliability index of 94.4 % after 200 accelerated thermal cycles. Thermogravimetry analyzer (TGA) results showed good thermal stability of MEGA. The dispersion stability and thermal conductivity of MEGA suspensions displayed significant enhancements compared to those of GA suspensions. Furthermore, compared with the base fluid, the MEGA suspensions with 1.0 wt%, 5.0 wt% and 10.0 wt% demonstrated reduced pumping power requirements by 16.9%, 54.6% and 70.0%, respectively. These findings suggest that MEGA holds promising prospects for applications in the medium temperature energy storage field.