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 direct-current 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.
Highlights
IntroductionThe fuel rate was in the range of 20– 60 mL/min
The stable working ranges of a small-scale combustor became narrower under the DC 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; 2
Summary
The fuel rate was in the range of 20– 60 mL/min They analyzed the electrical behavior as part of an electrical circuit for control by designing a fairly simple proportional–integral–derivative (PID) control algorithm. Ata et al.[30] experimentally studied the stability enhancement of conical premixed flames by application of DC electric fields and found that the pronounced effects were observed for the turbulent flames stabilized at the tip of a circular cylindrical bluff-body flame holder. Electrons and ions are present in flames, and because of charge separation, weak electric fields can be generated even when there is no externally applied electric field.[32] A theoretical and numerical model for ionized methane–air flames was developed to predict the electric currents based on the charged particle distribution in the flame.[33]
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