Control of Combustion Dynamics by an Electric Field

An experimental study was conducted by applying a DC electric field to the swirling flame of hydrocarbons with the aim to provide electric control of the gasification/combustion characteristics of biomass (wood pellets). An experimental study of the DC electric field effect on the biomass gasification/combustion characteristics was carried out by varying the bias voltage and polarity of the axially inserted electrode in the range ±0.9 to ±2.7 kV, whereas the ion current was limited to 2 mA. The field effect on biomass gasification was estimated by measuring the field-induced variations of the biomass mass loss rate. The electric field effect on combustion dynamics at thermo chemical conversion of biomass was estimated from complex measurements of the flame velocity, temperature and composition profiles and from calorimetric measurements of cooling water flow. The measurements of the biomass mass loss rate confirm the field-enhanced thermal decomposition of biomass (up to 12-16 %) with field-enhanced mixing of the flame compounds, as well as the improvement of combustion conditions for flaming combustion of volatiles and the radial expansion of the flame reaction zone. The field-enhanced thermal decomposition of biomass and flame homogenization results in increase of the average value of the CO2 volume fraction in the products by 4-10 % with a correlating decrease of the air excess by 2-6 % in the products as well as in increase of the average temperature values by 2-6 %, whereas the produced heat energy at field-enhanced thermo-chemical conversion of biomass increases by 3-5 % indicating a more complete combustion of volatiles and a more effective heat energy production.