Heat balance modeling and pathway analysis in membrane-covered aerobic composting: regulatory mechanisms of membrane...

Membrane-covered aerobic composting (MCAC) demonstrates enhanced heat retention capacity; however, the underlying heat transfer mechanisms regulated by semi-permeable membranes remain unclear. In this study, a coupled heat balance model was developed by integrating microbial heat generation, multi-pathway heat loss, and membrane-regulated transport processes. The model accurately reproduced the thermal dynamics of MCAC, achieving high predictive performance for pile temperature (R² = 0.89, RMSE = 2.88 ℃) and oxygen uptake rate (R² = 0.86, RMSE = 0.0144 mol O₂ kg^-1 VS h^-1). Heat loss pathway analysis revealed that wall heat transfer dominated total heat dissipation, while membrane covering altered the heat loss structure by suppressing evaporative heat loss and weakening convective exchange at the upper boundary. Sensitivity analysis further identified water vapor transmission rate as the key parameter controlling heat distribution, with a direct impact on evaporative heat loss and thermophilic phase duration. The results suggested that the thermal insulation effect of MCAC was more sensitive to water vapor diffusion than to thermal conductivity within the scope of the present model. This mechanistic insight highlights the central role of vapor transport in governing system thermal behavior and provides a theoretical basis for membrane selection and process optimization in MCAC systems.