Thermal performance of a meso-scale combustor with electrospray technique using liquid ethanol as fuel

A new meso-scale combustor designed to couple with energy conversion modules is fabricated. The volume of the combustor is of the order of a few cubic centimeters. Liquid ethanol is electrosprayed at a flow rate of 3.50 ml/h. The stable flame is observed to be in a disc shape near the mesh of the combustor when the equivalence ratios varying from 0.9 to 1.7 without external heating and catalyst. The temperatures of flame, combustor outer wall and exhausted gas are measured. Flame temperatures are within the range of 1134–1287 K. Exhausted gas components are detected by a gas chromatograph and the combustion efficiencies of ethanol are calculated, which are from 51.2% to 92.4%. Heat loss from the combustor wall is evaluated and it accounts for 29.2–43.6% of the input energy. The outer wall temperature distributions along the flow direction are obtained and a heat recirculation zone is found at about 10 mm away in the upstream of the mesh, which is beneficial to stable combustion. The mesh in the present combustor is used not only as a collector for gathering charged droplets but also a flame holder. The thermal efficiencies of the combustor are found to vary from 22.0% to 48.8%.