Influence of Particle Size Reduction on Combustion Properties and Thermal Behaviour of Agricultural Biomass

Particle size distribution is a critical determinant in the thermochemical conversion of lignocellulosic biomass. This research evaluates the impact of comminution on the calorific value and thermal kinetics of wheat straw, corn stalks, and hardwood chips (0.25–2.0 mm fractions). Experimental analysis demonstrates an inverse correlation between particle size and Higher Heating Value (HHV), with fine hardwood fractions achieving up to 20.03 MJ/kg—a relative increase of ~5.6%. Thermogravimetric analysis (TGA) identified a significant enhancement in thermal reactivity, evidenced by a 25–30°C shift in exothermic peaks toward lower temperatures. Additionally, the improved bulk density of finer fractions contributes to higher volumetric energy density, crucial for efficient storage and logistics. The study concludes that incorporating granulometric data into predictive models is essential for accuracy. Practically, these optimized properties facilitate more stable ignition and lower start-up loads in industrial grate and fluidized-bed boilers.