MicroPCM-based phase change energy storage backfill materials: Application potential in geothermal exploitation

Geothermal extraction, as one of the most highly regarded renewable energy sources of the 21st century, how to combine backfilling mining with geothermal extraction is an important research direction in the mining industry. To achieve this goal, optimization and improvement of backfill materials are essential. This paper proposes incorporating microencapsulated phase change materials (MPCM) into tailings at varying ratios to create phase change energy storage backfill (PCESB). The performance of PCESB is systematically evaluated through mechanical property tests, thermal analysis, pore structure characterization, and microscopic morphological observations. The results show that an MPCM content of ≤ 10 % significantly enhances the toughness, plasticity, energy absorption, and crack resistance of PCESB, while partially improving its strength after phase transition. However, exceeding 10 % MPCM content leads to a marked reduction in mechanical strength. As MPCM content increases, the thermal conductivity and porosity of PCESB initially rise before decreasing, while its heat storage performance continuously improves, greatly enhancing its thermal storage and release capacity. Excessively high MPCM content can also cause pore damage and leakage. A comprehensive evaluation of both thermal performance and economic feasibility suggests that 10 % MPCM content is optimal for PCESB, as it ensures efficient heat conduction and storage while maintaining favorable mechanical properties. This makes it suitable for practical applications in geothermal exploitation and underground engineering cooling. Future research could focus on further optimizing MPCM content and distribution to develop backfill materials with superior performance, thus advancing the efficient use of geothermal energy and cooling technologies in underground engineering. • A phase change energy storage backfill (PCESB) based on MPCM is proposed. • The thermal and mechanical performance of the PCESB is analyzed from multiple perspectives. • A platform for testing thermal storage and release performance was developed. • The optimal concentration of MPCM was determined. • The potential applications of the PCESB were explored.