اثر ت کرشته کربن اصلا حشده بر پایداری شکلی، کاهش نشتی وکارایی ذخیره گرمایی سامانه تغییر فاز بر پايه پلی اتیل نگلیکول

Hypothesis: Phase change materials (PCMs) can store latent heat energy during the phase change from solid to liquid. In previous studies, researchers have usually used the microencapsulation method to solve the leakage problem during melting. However, this method has led to issues such as high cost, difficulty of encapsulation, low thermal conductivity, and complexity of product quality control. In this research, to solve the problem of leakage, the method of impregnating PCMs into a porous supporting structure has been used. The porosity of the supporting material allows the phase change material (in liquid state) to flow freely throughout the 3D network and accommodates a greater percentage of PCM. Porous materials prevent the leakage of PCMs due to the improvement of capillary force. Methods: To solve the leakage issue of PEG, as the PCM, carbon monofilaments (CF) were used as a supporting material and adapted to improve the compatibility with PEG. After oxidizing CF by acidic solution, its surface modification was done with toluene di-isocyanate and ethylene glycol at a temperature of 90 ºC. The new phase change system was made by impregnating molten PEG in modified CF with a combination of 3 to 6% by weight at 80 °C. Findings: Chemical modification can create various functional groups on the surface of CF and, as a result, better miscibility with PEG. Due to the physical connection between PEG and modified CF, the leakage of the phase change system reached 2.42%, while the enthalpy efficiency of the system decreased by only 15%. On the other hand, the thermal diffusivity of the phase change system containing CF was found as 1.2 ×10-8 m2. s-1. So an integrated and stable system with a thermal energy absorption of about 44% has been created..