Low-temperature plasmas are gaining a lot of interest for environmental and energy applications. A large research field in these applications is the conversion of CO into chemicals and fuels. Since CO is a very stable molecule, a key performance indicator for the research on plasma-based CO conversion is the energy efficiency. Until now, the energy efficiency in atmospheric plasma reactors is quite low, and therefore we employ here a novel type of plasma reactor, the gliding arc plasmatron (GAP). This paper provides a detailed experimental and computational study of the CO conversion, as well as the energy cost and efficiency in a GAP. A comparison with thermal conversion, other plasma types and other novel CO conversion technologies is made to find out whether this novel plasma reactor can provide a significant contribution to the much-needed efficient conversion of CO . From these comparisons it becomes evident that our results are less than a factor of two away from being cost competitive and already outperform several other new technologies. Furthermore, we indicate how the performance of the GAP can still be improved by further exploiting its non-equilibrium character. Hence, it is clear that the GAP is very promising for CO conversion.

In this computational study, a gliding arc plasma reactor with a reverse-vortex flow stabilization is modelled for the first time by means of a fluid plasma description. The plasma reactor is operating with argon gas at atmospheric pressure. The gas flow is simulated using the kε RANS turbulent model. A quasi-neutral fluid plasma model is employed for computing the plasma properties. The plasma arc movement in the reactor is observed, and the results for the gas flow, electrical characteristics, plasma density, electron temperature, and gas temperature are analyzed.

The gliding arc plasmatron (GAP) is a highly efficient atmospheric plasma source, which is very promising for CO2 conversion applications. To understand its operation principles and to improve its application, we present here comprehensive modeling results, obtained by means of computational fluid dynamics simulations and plasma modeling. Because of the complexity of the CO2 plasma, a full 3D plasma model would be computationally impractical. Therefore, we combine a 3D turbulent gas flow model with a 2D plasma and gas heating model in order to calculate the plasma parameters and CO2 conversion characteristics. In addition, a complete 3D gas flow and plasma model with simplified argon chemistry is used to evaluate the gliding arc evolution in space and time. The calculated values are compared with experimental data from literature as much as possible in order to validate the model. The insights obtained in this study are very helpful for improving the application of CO2 conversion, as they allow us to identify the limiting factors in the performance, based on which solutions can be provided on how to further improve the capabilities of CO2 conversion in the GAP.

In recent years there is growing interest in the use of plasma technology for CO2 conversion. To improve this application, a good insight in the underlying mechanisms is of great importance. This can be obtained from modeling of the detailed plasma chemistry, to understand the chemical reaction pathways leading to CO 2 conversion (either in pure form or mixed with another gas). Moreover, in practice several plasma reactor types are being investigated for CO 2 conversion, so in addition it is essential to model these reactor geometries, in order to be able to improve their design, and to achieve the most energy efficient CO2 conversion. Modeling the detailed plasma chemistry of CO2 conversion in complex reactors is, however, very time-consuming. This problem can be overcome by using a combination of two different types of models. 0D chemical reaction kinetics models are very suitable for describing the detailed plasma chemistry, while the characteristic features of different reactor geometries can be studied by 2D or 3D fluid models. The latter can in first instance be developed in argon or helium, with a simple chemistry, to limit the calculation time, but the ultimate aim is to implement the more complex CO2 chemistry in these models. In the present paper, examples will be given of both 0D plasma chemistry models and 2D and 3D fluid models for the most common plasma reactors used for CO2 conversion, to emphasize the complementarity of both approaches. Furthermore, based on the modeling insights, the paper discusses the possibilities and limitations of plasma-based CO 2 conversion in the different types of plasma reactors, and what would be needed to make further progress in this field.

A Gliding Arc Plasmatron (GAP) is very promising for CO 2 conversion into value-added chemicals, but to further improve this important application, a better understanding of the arc behavior is indispensable. Therefore, we study here for the first time the dynamic arc behavior of the GAP by means of a high-speed camera, for different reactor configurations and in a wide range of operating conditions. This allows us to provide a complete image of the behavior of the gliding arc. More specifically, the arc body shape, diameter, movement and rotation speed are analyzed and discussed. Clearly, the arc movement and shape relies on a number of factors, such as gas turbulence, outlet diameter, electrode surface, gas contraction and buoyance force. Furthermore, we also compare the experimentally measured arc movement to a state-of-the-art 3D-plasma model, which predicts the plasma movement and rotation speed with very good accuracy, to gain further insight in the underlying mechanisms. Finally, we correlate the arc dynamics with the CO 2 conversion and energy efficiency, at exactly the same conditions, to explain the effect of these parameters on the CO 2 conversion process. This work is important for understanding and optimizing the GAP for CO 2 conversion.