Porosity-driven combustion behavior in fluffy biomass waste: Toward safer and smarter energy utilization

Abstract

Biomass fractions within municipal solid waste present significant fire hazards and environmental pollution risks, amplified by their distinct physical architectures. Discarded cotton wadding and poplar fluff, characterized by porous, fluffy morphologies and high specific surface areas, readily form combustible air-premixed systems during storage and transport, posing risks of uncontrolled fires and associated pollutant release. Understanding the combustion kinetics of such waste streams is critical not only for fire safety but also for assessing their potential for efficient energy conversion and minimizing incomplete combustion emissions. This study focused on a representative elongated fibrous biomass: waste cotton floc. By integrating microscopic structural characterization with theoretical combustion modeling, we systematically uncovered the unique deflagration behavior and latent hazards associated with this class of materials, linking them to potential environmental impacts. A custom setup with high-speed imaging quantified flame spread (1.5 m/s in confined conditions vs. 0.8 m/s in open conditions) and reaction times. Confined burning, which mimics common waste accumulation scenarios, such as containers or piles, displayed 85% faster propagation but lower combustion efficiency (stabilizing at ~20% with higher fuel loads) and ultra-short combustion durations (0.2 s at peak loading); these conditions favor incomplete combustion and elevated pollutant generation. The proposed structural fuel theory identified porosity as the key control parameter, linking fiber network topology to combustion dynamics and pollutant formation potential. These insights are vital for advancing strategies to mitigate combustion-related pollution events, optimize waste biomass energy recovery efficiency, and enhance fire safety protocols within the waste management sector to protect environmental quality.

Keywords

Biomass waste / Biomass energy / Long fibers / Porosity / Deflagration

Funding

This study was funded by the Beijing Forestry University through a grant awarded to Zhongjia Chen (grant number: 31500478).

Conflict of interest

The authors declare that they have no known competing financial interests or personal relationships that could have influenced the work reported in the article.

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