Electric field-controlled mesoscale burners

Abstract

The use of field-induced drag exercised on corona-generated ions is optimised for inducting the air needed for stoichiometric combustion in compact, simple, lightweight, robust and self-contained burners with no moving parts. These burners operate with a wide variety fuels without sooting, at intensities sufficient to release power in the region of several kW. Gaseous and liquid fuels are injected and the flame stabilized immediately above an earthed ring electrode using various designs of capillary feeds to wicks of ceramic wool which also act as porous plug burners and bluff body flame stabilizers. The several regimes of flame stabilization at various flow velocities are discussed. Blowers involving multi-staging and the addition of field-induced swirl are explored but the favored ion blower design is the simplest, smallest and most economical. At about 7 ml in volume, it can deliver some 1.2 L/s of air, corresponding to a thermal output of 4–5 kW for stoichiometric hydrocarbon mixtures. The fraction of a Watt needed for the ion-driven air induction is so negligible a proportion of the thermal output that, if necessary, it could be generated thermoelectrically at the burner mouth. Short, premixed, highly turbulent flames are stabilized for C n H 2 n+2 with n = 1 , 3, 6, 10 and with meths (denatured ethanol), for the smallest blower dimensions, operating at an electrical input of about 0.4 W. The largest thermal power outputs for a given wick area are achieved with those fuels that are least prone to sooting. The burner is designed to operate also in the absence of natural convection; i.e., in microgravity environments.