Heat transfer mechanism of superabsorbent polymers phase change energy storage cold-formed steel wall under fire

The superabsorbent polymer phase change materials (SAP materials) exhibit exceptional water absorption and retention properties, offering substantial potential for fire protection in steel structures, thereby reducing the need for sheathing boards and fire-retardant coatings, while minimizing energy consumption. Understanding the heat-mass exchange theory of SAP materials is crucial for enhancing their application in the building industry. This study develops a comprehensive theoretical model for heat-mass exchange in cold-formed steel (CFS) walls incorporating SAP materials. An equilibrium phase change model and a simplified thermal radiation model were developed to capture the water loss and dynamic heat exchange processes in SAP materials. These models were integrated into a transient fluid-solid-thermal coupling model using Ansys Fluent and User Defined Functions. In the case study, the newly developed numerical models can accurately predict temperature field changes in CFS walls with SAP materials, demonstrating the heat transfer mechanisms of hot and cold flanges at different temperature rise stages. The developed numerical model was used to investigate the effects of factors such as the moisture content of the SAP material, web depth, and flange width on the fire resistance of the CFS wall. Results indicated that increasing the wall stud height improves fire resistance, while increasing flange width has little effect on hot flange temperature. These findings provide a theoretical foundation and practical guidelines for the application of SAP phase change insulation materials in the building industry, promoting energy reduction and supporting sustainable construction practices.