Net emission coefficient for CO-H2 thermal plasmas with the consideration of molecular systems

highlights
- We calculate radiative losses from CO-H2 thermal plasmas.
- We use the up-to-date atomic and molecular databases.
- The influence of CO2 molecule is very important at low temperature.
- The relative maximum of the net emission coefficient at low temperature is unusual.

This paper deals with the calculation of net emission coefficients (NECs) for CO-H2 thermal plasmas. This task required the elaboration of a complete spectroscopic database including atoms and molecules formed by carbon, oxygen and hydrogen elements. We have used a systematic line by line method to calculate all the main radiative contributions which are the atomic and molecular continua, the atomic lines and the molecular (diatomic and polyatomic) lines. The main diatomic electronic systems for CO-H2 plasmas and the triatomic molecular bands were considered. We present some variations of the net emission coefficient versus temperature, for various pressures and for two relative proportions of the components. The role of the diatomic molecules is important at temperatures lower than 5000 K whereas the net emission coefficient presents an unusual peak at temperature around 1000 K, due to the presence of the CO2 molecule presenting a strong infrared radiation. Finally, the results show that the NEC slightly depends on the relative proportion of CO and H2.