Influence of electric field on thermo-chemical conversion of mixtures of straw pellets with coal

Abstract

Abstract. The recent research is focused on experimental study and mathematical modelling of the development of combustion dynamics at thermo-chemical conversion of biomass mixtures (straw pellets with crashed coal) with the aim to better understand the effect of electric field on the formation of the main gasification/ combustion characteristics when co-combusting straw with crashed coal. The experimental study and numerical modelling of the electric field effects on the combustion dynamics, when co-combusting straw pellets with coal, were carried out to ensure wider use of straw as a fuel for energy production providing the electrodynamic process control. The mathematical model considers the electric field influence on the combustion characteristics using the approximation of 2D axially symmetric compressible swirling flow and chemical reactions with account of the development of A→B↔C kinetics (A -reactant, B -intermediate product, C -final product) downstream the cylindrical combustor.Keywords: biomass pellets, electric field, chemical reactions, mathematical model. IntroductionThe electric field effect on diffusion and premixed flames attract attention as a tool, which allows to control the flame shape, structure and the main flame characteristics, such as the flow velocity, flame temperature, composition, equivalence ratio and products composition [1][2][3][4][5][6]. There are different mechanisms of the electric field effect on the main flame characteristics. First, at high current density, the electric field effect on the flame can be related to the flame heating, with an additional heat input into the flame (plasma support of combustion). Next, the electric body forceinduces an ion drift motion in the field direction.Inelastic collisions between the flame ions and the neutral flame species can then cause the ion wind effect promoting the interrelated processes of field-enhanced heat and mass transfer in the field direction. This can cause variations of the thermal decomposition of solid fuels and the combustion of volatiles. In addition, the electric field-induced inelastic collisions between the electrons and the flame species can cause variations of the rate of reactions. Finally, the flame dynamics can be controlled using the Lorentz force, when the electric field-induced current in the flame reaction zone creates a field-induced magnetic field with axial and radial components of the electromagnetic force, which influence the evolution of flow dynamics and flow vorticity [7]. Thus, multiple factors can influence the development of combustion dynamics, when the electric field is applied to the flame. In order to obtain predictable and controllable field effect on the main flame characteristics, one can vary such parameters as the electric field polarity, bias voltage and current density between the electrodes.More precise and systematic studies of the electric field effect on the combustion dynamics for different types of flames (diffusion, swirling, etc.) and fuels (gaseous, solid and their mixtures)...

On obtaining numerical solutions for some reacting flow problems by using different matlab tools

“…Here we provide a brief review of the experimental results, published in prior works, such as [3,4]. In order to initiate the discussion on comparison of experimental and modelling (to be presented below) DOI: 10.22616/ERDev.2021.20.TF343 results, the pictures from the mentioned articles the author has been involved in have been replicated in the present article.…”

Numerical study of electrodynamic control of straw co-firing with propane

“…with maximum value equal to 1; and at the axially inserted electrode for smooth round wire r = 1/80: Φ = q = 0 .These BCs are used also for initial conditions by t = 0. In [8] the electric field modelling is without the ion mobility and the charge distribution at the surface electrode. In Fig.…”

Mathematical Modelling and Experimental Study of Straw Co-Firing With Gas

“…The action of the electric body force results in reduction of the free flame length. The maximum field effect was achieved with a 10-20% straw mass fraction in the fuel mixture (peat, wood, coal) [2], [15], [17].…”

“…In [2], [14], [15], [17], the applied electric field induces an electric current between the walls of the combustor and the axially inserted electrode of different length. The perfect gas model is used to solve the inviscid, axisymmetric, steady swirling flow with axial and radial velocities and with circulation.…”