MODELISATION ET OPTIMISATION DE LA CONVERSION D'UNE BIOMASSE ALGALE ET DE LA CELLULOSE PAR PROCÉDÉ DE LIQUEFACTION HYDROTHERMALE

Abstract

Hydrothermal liquefaction (HTL) is an innovative thermochemical process that enables the conversion of wet biomass, such as cellulose and microalgae (Chlorella protothecoides), into bio-oil without the need for a prior drying step. This thesis combines an experimental study on cellulose with a multiphysics modeling approach using COMSOL Multiphysics, incorporating reaction kinetics, heat transfer, and mass transfer. Process optimization was performed using a Box-Behnken design of experiments, based on four key operational parameters: temperature, residence time, pressure, and biomass concentration. The numerical simulations were validated with experimental data and allowed for the prediction of yields in bio-oil, aqueous phase, and gas. Temperature was identified as the most influential factor, followed by significant interactions among the other variables. The results highlight the relevance of an integrated approach combining experimentation and multiphysics modeling to optimize HTL performance and enhance biomass valorization in the context of sustainable energy transition.