Study on Permeability and Flow Characteristics of Composite Thermosensitive Hydrogel and Its Fire Prevention and Extinguishment Performance.

This study focuses on the issues of poor fluidity, low penetration into residual coal, and suboptimal inhibition of coal spontaneous combustion associated with traditional coal mine gel fire retardants. The permeability and flow characteristics of a sodium alginate-based composite thermosensitive hydrogel, as well as its fire prevention and extinguishment performance, were investigated. The findings suggest that the thermosensitive hydrogel behaves as a pseudoplastic fluid at 40 °C and a yield-pseudoplastic fluid at 65 °C, exhibiting shear-thinning behavior with increasing shear rate. In a 1000 m pipeline transportation system, the hydrogel's shear rate was 108.838 s, and the pipeline pressure drop was 1.608 MPa, confirming its suitability for pipeline transport. The mass retention ratio of the hydrogel in coal samples was 23.94%, nearly twice that of water, indicating better retention in coal samples. The rate of hydroxyl consumption in coal samples subjected to the hydrogel treatment decreased by approximately 40 times. Upon heating, the CO generation rate of the hydrogel-treated coal remained lower than that of the untreated coal, while its activation energy was higher. Additionally, the hydrogel effectively reduced coal temperature rise and provided a sustained cooling effect on the oxidation process, significantly enhancing fire prevention and extinguishment efficiency.