Effects of direct-current electric fields on flame shape and combustion characteristics of ethanol in small scale

Abstract

The aim of this work is to investigate the effects of direct-current electric fields on the behavior of the small-scale diffusion ethanol flame. The flow rate of liquid ethanol, the flame temperatures, and the flame shapes were measured. The results showed that the stable working ranges of a small-scale combustor became narrower under the direct-current electric field. The main reason was that the evaporation velocity of liquid ethanol limited by great heat loss effect cannot keep up with the increasing of combustion velocity by the ionic wind effect. The movements of those charged particles in flame enhanced the combustion process, resulting in higher flame temperatures under positive or negative directcurrent electric field. The flame heights decreased with increasing applied voltages, due to the ionic wind effect increasing the flame temperature and the diffusivity. The flame voltage-current characteristic was also examined. Three regions can be divided: the subsaturation region, the saturation region, and the supersaturation region. Finally, the ratios of electric active power to actual burning thermal power of ethanol flame were calculated. It can be inferred that using the external direct-current electric field with little power consumption to control combustion and flame is a feasible method.

Investigation of the effect of DC electric field on a small ethanol diffusion flame

“…Energy: In our previous work [28], it was found that the external electric energy was very small compared with the actual burning thermal energy of ethanol in this study. This was also mentioned in the reference [22].…”

“…So the temperature at the top position was chosen to represent the flame temperature. Moreover, the measurement at the top position brought the smallest disturbance to the flame compared with other positions[28].…”

“…The measurement system consisted of digital camera (Cannon, EOS 5D Mark Ⅲ) to observe the flame shape, S type platinum-rhodium thermocouple with the node diameter of 0.3 mm, and data acquisition instrument (Agilent, 34970A) to measure the flame temperature, which also could collect data of current and voltage. The system is similar to that used in our previous work [27][28][29].…”

Electric Field Damping of Rijke Tube Combustion Instabilities

“…Research on the effects of a dc field on a hydrocarbon flame has been done by many researchers [12][13][14][15][16][17][18][19]. Results have shown the electric field capable of increased lean blowoff limits, increased flame burning velocity, decreased emissions and soot formation, and enhanced flame stability.…”

Electric field effects on gasification/combustion at thermo-chemical conversion of biomass mixtures

“…The use of the electric field (EF) to control the combustion characteristics for different types of hydrocarbon fuels (gaseous, liquid, solid) is considered as an effective tool to provide the local variations of flow dynamics, flame shape, structure, composition, temperature, heat output and composition of emissions, as well to improve the flame [1][2][3]. The results of the experimental study and theoretical analysis suggest that the main mechanism, which leads to the variation of the combustion dynamics can be related to the ion wind effect, when the electric field-induced body force initiates the acceleration of the flame ions (CHO + , H 3 O + , C 2 H 3 O + , O 2 -, OH -, CHO 3 -) in the field direction with subsequent momentum transfer to neutral flame species [1].…”