Term of Award

Fall 2025

Degree Name

Master of Science, Mechanical Engineering

Document Type and Release Option

Thesis (restricted to Georgia Southern)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.

Department

Department of Mechanical Engineering

Committee Chair

Prakash Bhoi

Committee Member 1

Sevki Cesmeci

Committee Member 2

David Calamas

Abstract

The development of a robust bioeconomy presents a strategic approach to mitigate escalating atmospheric CO2 concentrations and their associated greenhouse gas emissions through the utilization of sustainable and approximately carbon-neutral biomass resources. Moreover, the deployment of advanced green energy technologies such as biofuels and fuel cells offers viable pathways to address the increasing energy demand and reduce the dependence on conventional fossil fuels. One of the promising processes is biomass gasification which produces synthesis gas (primarily H2 and CO) that can be converted into liquid fuels through a Fischer–Tropsch synthesis technique. Another pressing environmental issue is the accumulation of waste mixed plastics in landfills. Gasification of these waste plastics in combination with biomass could transform waste into commercially viable fuels and chemicals. This study aims to develop computational fluid dynamics (CFD) models incorporating the discrete phase model (DPM) to evaluate the steam and CO2 gasification of biochar and the steam co-gasification of waste mixed plastics and biochar. The species transport model was employed to incorporate both volumetric and particle surface reactions, utilizing the Finite-rate/Eddy-dissipation approaches and a multiple surface reaction model. These plastics were incorporated into the CFD model of the gasifier as gaseous species resulting from the pyrolysis process, implemented through a user-defined function. The model was validated against our experimental data, yielding an absolute error of 2.27% in predicting the mole fraction of H2 in the syngas. The highest amount of hydrogen was 63.83 vol% in the syngas, obtained when the plastic-to-biochar ratio was 0.3 and the steam flow rate was 5 ml/min at 950°C. The model developed for the CO2 gasification process was validated with our experimental data, with an error margin ranging from 3% to 10%. In the CO2 gasification simulations, the CO2 concentration varied from 15 to 60 vol.%, and the temperature varied from 700°C to 900°C. Among these conditions, a CO2 concentration of 60% at 900°C yielded the highest CO production; however, the CO2 conversion efficiency was low. The highest CO2 conversion efficiency was observed at low CO2 concentrations (15% CO2 and balance Nitrogen).

Research Data and Supplementary Material

No

Download

Available for download on Friday, November 20, 2026

Share

COinS