Abstract
This project conducted a literature study and numerical simulations on thermal hydrogen plasma. The main goal was to model hydrogen plasma in a non-transferred plasma torch. The primary motivation behind the simulation is the move from carbon dioxide-based reduction processes of metal oxides to cleaner reduction processes with hydrogen plasma. Plasma reactors are expensive to build, and the inner workings of the torch are not entirely understood as it is challenging to extract experimental data. Hence, modeling it in software such as OpenFOAM can create data that might help understand hydrogen plasma behavior and design better plasma reactors. A case and solver procedure were constructed in OpenFOAM using data and models from the literature study. The case was a steady-state laminar system with an axisymmetric geometry. The axisymmetry was centered on the symmetry axis of the cathode in the non-transferred plasma torch. Governing equations for mass, momentum, and energy were implemented, along with an electromagnetic model. These models enabled the coupling of an electric current with the conservation equations of the plasma through the source terms of Joule heating and Lorentz force. In addition, polynomials of thermophysical properties were implemented to capture the dynamic response of the plasma to the heat from the electric current. Hydrogen and argon plasma was simulated using the case setup, and a simple parameter study was performed. The argon results were compared to earlier work, which uses the same geometry and parameters. In addition, the results of the hydrogen and argon parameter study were also compared to the literature of parameter studies on hydrogen and argon. The results show that the temperature field resembles the earlier work, but the temperature was lower than expected. The low temperature could be attributed to the polynomial regression, which is not accurate enough to capture the plasma properties. Furthermore, the response to the parameters such as inflow velocity and current resembles litterateur results, but the arc behaves drastically different from what is expected. This result shows that the electromagnetic model and Lorentz force implementation needs more attention. In addition, the hydrogen results are questionable as they did not meet the requirement for convergence.