Aerobic fermentation of corn straw for clean heat utilization: an evaluation model

The idling of corn straw (CS) resources and non-environmentally friendly heating models in rural areas create a disconnect between energy production and consumption. Under the common practice of obtaining organic fertilizers through composting, a large amount of aerobic fermentation heat (AFH) is generated and wasted. This study aims to develop a model to evaluate the heating potential of AFH for clean heating and guide its engineering application. Using CS as the research object, the effects of temperature, carbon-nitrogen ratio, and water content on degradation rates were analyzed based on degradation kinetics. Integrating the energy balance equation, an AFH output model was established to analyze design requirements of fermentation reactors and heat supply potential. The results show that the optimal degradation rate of CS was 13.22 %·d⁻¹, approximately 40 % of that of sludge. The model accurately predicted temperature change during aerobic fermentation with an average relative error of 4.03 %. Through model prediction, a 100 m³ system achieved a heat supply efficiency of 4.7 MJ kg⁻¹ at 0 °C, accounting for 46.9 % of AFH production and approximately 30 % of the total energy. These findings demonstrate the feasibility of AFH engineering in low-temperature environments and offers a potential clean heating approach for rural areas.