Microfluidic fabrication of phase change materials capsules with polyanine-reinforced shells for enhanced mechanical and thermal properties

Thermal energy storage using phase change materials (PCMs) plays a vital role in enhancing energy efficiency across various applications, with the performance of PCM capsules being a critical determinant in packed bed thermal energy storage (PBTES) systems. This study introduces an innovative strategy to overcome the inherent limitations of low thermal conductivity and mechanical strength in conventional capsule shells by developing microfluidic-fabricated PCM capsules featuring polyaniline (PANI)-reinforced calcium alginate (CA) shells. An optimal PANI concentration of 2% is identified, which synergistically enhances the shell's thermal conductivity by 22% (from 0.6932 to 0.8451 W/(m·K)) and its mechanical strength, evidenced by a 22.69% increase in yield strength (from 658.08 to 807.37 kPa) and a 35% improvement in elastic modulus compared to pure CA shells. System-level experimental evaluation demonstrates that integrating these reinforced capsules into a PBTES system significantly improves thermal performance, reducing charging time by 6.25%, at a flow rate of 0.2 L/min. Comprehensive energy and exergy analyses confirm an increase in charging energy efficiency and exergy efficiency, indicating a reduction in thermodynamic irreversibilities. Although the incorporation of PANI results in a minimal reduction (∼0.1%) in the energy storage capacity due to the altered specific heat of the shell material, this is decisively offset by the enhancement in thermal conductivity and improvement in mechanical strength. The PANI-reinforced capsules presented herein offer a promising and effective solution for advancing the development of efficient, responsive, and durable PBTES systems. • Microfluidic-fabricated PCM capsules with PANI-reinforced shells • Dual 22% enhancement in shell thermal conductivity and mechanical strength • PBTES charging/discharging time reduced by 6.25% and 4.57% at 0.2 L/min