Based on an equilibrium fluid model, built from the commercial Fluent software previously validated for thermal plasma characterizations on several geometries, a non-equilibrium two-temperature model was developed. This kind of model needs the use of two energy equations: one for the electrons, and the other for heavy particles.Nevertheless, depending on the authors, divergences exist in the expressions of equations. The main differences are related to the attribution of the ionization term and to the components of thermal conductivity in the energy equations.The two-temperature model developed is applied in a transferred arc configuration where the medium is described using the different formulations for the energy equations.The right formulation, based on the Boltzmann equation, is then applied in a transferred arc configuration for two values of current intensity of 100 and 600 A. We show that in order to obtain coherent and physical results in all the cases, special attention needs to be given: the ionization term, the reactive thermal conductivity and the radiation line contribution need to be considered in electron energy equations, whereas the reactive thermal conductivity due to dissociations and the continuum radiation contributions need to be associated with the heavy energy equations.

http://iopscience.iop.org/article/10.1088/0022-3727/45/46/465206/pdf

Energy equation formulations for two-temperature modelling of ‘thermal’ plasmas

Variational multiscale method for nonequilibrium plasma flows

A self-consistent and complete numerical model for investigating the fundamental processes in a non-equilibrium thermal plasma system consists of the governing equations and the corresponding physical properties of the plasmas. In this paper, a new kinetic theory of the transport properties of two-temperature (2-T) plasmas, based on the solution of the Boltzmann equation using a modified Chapman–Enskog method, is presented. This work is motivated by the large discrepancies between the theories for the calculation of the transport properties of 2-T plasmas proposed by different authors in previous publications. In the present paper, the coupling between electrons and heavy species is taken into account, but reasonable simplifications are adopted, based on the physical fact that me/mh ≪ 1, where me and mh are, respectively, the masses of electrons and heavy species. A new set of formulas for the transport coefficients of 2-T plasmas is obtained. The new theory has important physical and practical advantages over previous approaches. In particular, the diffusion coefficients are complete and satisfy the mass conversation law due to the consideration of the coupling between electrons and heavy species. Moreover, this essential requirement is satisfied without increasing the complexity of the transport coefficient formulas. Expressions for the 2-T combined diffusion coefficients are obtained. The expressions for the transport coefficients can be reduced to the corresponding well-established expressions for plasmas in local thermodynamic equilibrium for the case in which the electron and heavy-species temperatures are equal.

A numerical model of non-equilibrium thermal plasmas. I. Transport properties

The energy tree: Non-equilibrium energy transfer in collision-dominated plasmas

https://iopscience.iop.org/article/10.1088/1361-6595/aac9fa/pdf

Advances and challenges in computational fluid dynamics of atmospheric pressure plasmas

Here the authors developed a two-dimensional two-temperature chemical non-equilibrium (2T-NCE) model of Ar–CO2–H2 inductively coupled thermal plasmas (ICTP) around atmospheric pressure (760 torr). Assuming 22 different particles in this model and by solving mass conservation equations for each particle, considering diffusion, convection and net production terms resulting from 198 chemical reactions, chemical non-equilibrium effects were taken into account. Species density of each particle or simply particle composition was also derived from the mass conservation equation of each one taking the non chemical equilibrium effect into account. Transport and thermodynamic properties of Ar–CO2–H2 thermal plasmas were self-consistently calculated using the first order approximation of the Chapman–Enskog method at each iteration point implementing the local particle composition and temperature. Calculations at reduced pressure (500 and 300 torr) were also done to investigate the effect of pressure on non-equilibrium condition. Results obtained by the present model were compared with results from one temperature chemical equilibrium (1T-CE) model, one-temperature chemically non equilibrium (1T-NCE) model and finally with 2T-NCE model of Ar–N2–H2 plasmas. Investigation shows that consideration of non-chemical equilibrium causes the plasma volume radially wider than CE model due to particle diffusion. At low pressure with same input power, presence of diffusion is relatively stronger than at high pressure. Comparison of present reactive model with non-reactive Ar–N2–H2 plasmas shows that maximum temperature reaches higher in reactive C–H–O molecular system than non-reactive plasmas due to extra contribution of reaction heat.

Two-Temperature Two-Dimensional Non Chemical Equilibrium Modeling of Ar–CO2–H2 Induction Thermal Plasmas at Atmospheric Pressure

In the present work, effect of CO2+H2 gas mixture inclusion on shrinkage of plasma was numerically investigated on high power Ar inductively coupled thermal plasmas at atmospheric pressure. The gas mixture of CO2+H2 has many reactions in wide temperature range of 300-20000K which may cause some performance in thermal plasmas. Simulation has been carried out solving a two-dimensional local thermodynamic equilibrium (LTE) code. The active plasma power and input fundamental frequency were fixed at 27kW and 450kHz respectively. The main variable parameter was the admixture ratio of secondary gas (CO2+H2 gas mixture) and it has been found that the injection of excess dissociative molecular gases shrink the plasma in radius keeping the center temperature about 10,000K by investigating the plasma radius having temperature beyond 5,000K for each of the case. The result also shows that increasing the inclusion (admixture ratio) of CO2+H2 molecular gas raises the plasma peak temperature. The result is also compared with that of Ar-CO2 and Ar-H2 thermal plasma and finally a comparative study and conclusions have been made.

/pdf/co2-and-h2-gas-mixture-inclusion-effect-on-shrinkage-of-ar-1h90a0frht.pdf

CO2 and H2 Gas Mixture Inclusion Effect on Shrinkage of Ar Induction Thermal Plasmas

Observation of non-chemical equilibrium effect on Ar-CO2-H2 thermal plasma model by changing pressure

In this work, a two-dimensional chemically non-equilibrium (NCE) model has been developed for Ar inductively coupled thermal plasma (ICTP) with C-H-O system at atmospheric pressure from the viewpoint of plasma process and fuel combustion Chemically non-equilibrium effects have been taken into account by solving mass conservation equations for each of 22 particles (including atoms, molecules, ions and electrons) considering convection, diffusion and net production effects For the net production term, totally 198 chemical reactions were taken into account including dissociation, ionization and other chemical reactions and their backward reactions

/pdf/chemically-non-equilibrium-modeling-of-argon-inductively-22isf8y2l3.pdf

Sharif Abdullah Al-Mamun

Papers

Two-Temperature Two-Dimensional Non Chemical Equilibrium Modeling of Ar–CO2–H2 Induction Thermal Plasmas at Atmospheric Pressure

CO2 and H2 Gas Mixture Inclusion Effect on Shrinkage of Ar Induction Thermal Plasmas

Observation of non-chemical equilibrium effect on Ar-CO2-H2 thermal plasma model by changing pressure

Chemically Non-Equilibrium Modeling of Argon Inductively Coupled Thermal Plasma with C-H-O Systems

Two-temperature non-chemical equilibrium analysis of Ar–CH4–O2 ICTP at reduced pressure