Preparation and performance of tubular carbon-based carbonate composites for thermochemical energy storage

In the context of large-scale utilization of renewable energy, the use of hydrated salts in thermochemical energy storage is seen as a critical solution to address the unpredictability and inconsistency of energy systems. Potassium carbonate was selected as the storage material due to its high energy density, safety, stability, and cost-effectiveness. A novel tubular carbon-based composite for potassium carbonate storage was developed using a centrifugal method, with carbon fiber (CF) chosen for its excellent thermal conductivity and microstructure, and perforated copper tube used for structural support. Five K2CO3-CF composites with CF contents of 6.7 %, 12.5 %, 17.6 %, 22.2 %, and 26.3 % by weight were fabricated. The CF22.2PC composite exhibited superior hydration performance, with an activation energy of 67.58 kJ/mol and a pre-exponential factor of 1.6132 × 108 s−1 for the hydrated reaction. Based on the characterization results, it is calculated that the porosity is 0.301, the theoretical thermal conductivity is 0.42 W/(m∙K), and the energy storage density in the anhydrous state is 516.90 kJ/kg. Simulations showed that high heat transfer fluid velocity, steam inlet pressure, and thermal conductivity positively influenced reaction rates, temperature increase, and power output. These findings suggest that this composite has significant potential to enhance the sustainability and reliability of energy systems.