Exergetic analysis and optimization of process variables in xylitol production: Maximizing efficiency and...

This study presents an exergetic analysis of xylitol fermentative production from hemicellulose hydrolysate, aiming to optimize operational conditions in a fluidized bed bioreactor. The aerobic fermentation conditions evaluated in this study (gas flow rate - x₁, hydrolysate concentration factor - x₂, and recirculation flow rate - x₃) were optimized using various exergetic parameters and xylitol yield as objective functions. Four objective functions were defined for the mono-objective optimization process: rational exergetic efficiency, normalized destroyed exergy, thermodynamic sustainability index, and xylitol yield factor. The results reveal that the optimization problem involves conflicting objectives when considering both yield-based and exergy-based approaches. Thus, the bioreactor's performance was formulated as a multi-objective problem, where the yield factor and thermodynamic sustainability index were simultaneously maximized. For the multi-objective optimization, the ideal operational variable ranges were found to be: 594 ≤x₁≤ 619 mL/min, x₂= 7 e 37 ≤x₃≤ 57 L/h.