Pore Characteristics and Thermal Properties of a Binary Eutectic Adsorbed into Modified Waste Navel Orange Peels for Energy Storage

Energy storage is an effective means to address rising energy consumption, and phase change materials (PCMs) can effectively improve energy storage efficiency and utilize renewable energy. In this work, sliced paraffin (PS) and lauric acid (LA) were employed as phase change raw materials and blended with freeze-dried navel orange peel carbon (FNOP). PS-LA/FNOP was prepared by vacuum adsorption. NOP is carbonized at three temperatures. It is determined that FNOP900 has an optimal pore volume and a specific surface area of up to 0.165 cm³/g and 339.04 m²/g, respectively. The optimal load rate of FNOP900 reaches 65%. The phase transition enthalpy and temperature of PS-LA/FNOP900 are 61.95 J/g and 36.42 °C, respectively. PS-LA/FNOP900 has an excellent thermal storage capacity at a constant temperature of 10–55 °C. After 300 thermal cycles, the enthalpy of PS-LA/FNOP only decreased by 9.15 J/g. Meanwhile, PS-LA/FNOP900 maintains good thermal reliability; the thermal conductivity of PS-LA/FNOP900 is 0.42 W/m·K, which is 47.84% higher than that of PS-LA. Also, PS-LA/FNOP900 exhibits superior temperature control performance; the heating and cooling times of PS-LA/FNOP900 are reduced by 11.68 and 50.03%, respectively, compared with PS-LA.