The combustion characteristics of liquid ethanol in air and oxygen–carbon dioxide environments are investigated numerically inside a vertical reactor. Gambit 2.2 was used to construct the mesh and Fluent 12.1 was used to perform the calculations. Different oxidizer environments were considered including pure air, oxygen-enriched air, in addition to the cases of OF21 (21% O₂ and 79% CO₂) and OF29 (29% O₂ and 71% CO₂). Comparisons were performed between the different cases and the results were validated against wide range of the experimental data. Nonpremixed combustion model which utilizes probability density function to predict the scalar quantities was incorporated to simulate the combustion process. Two turbulence models, realizable k–ɛ (RKE) model and Reynolds stress model (RSM), were applied and their results were compared. The Euler–Lagrange approach was utilized to solve the discrete phase model. The results showed the ability of the RKE model to predict much closer data to the experimental data than the RSM which over predicts the temperature. For the case of OF21, the flame was lifted and the combustion temperature was reduced as compared to the air combustion case. However, the OF29 combustion case resulted in a very close performance to the case of air combustion.