부산대학교 도서관

In the combustion of low vapor pressure liquid fuel, it is necessary for instantaneous ignition to preheat the liquid fuel evaporator at any required time. For example, in the kerosene vaporizing type boiler for home use, electric power is consumed in the preheating kerosene vaporization to supply hot water, even on standby. To avoid the preheating process by electric power during the standby period, the technology that can vaporize liquid fuel instantaneously needs to be developed. From this viewpoint, the application of the ultrasonic atomization was proposed to ignite liquid fuel without any heating process. Similar trials had already been done but no stabilized combustion was accomplished by ultrasonic atomizing, using an MHz frequency.In this work, a kerosene pre-mixed burner equipped with a 1.7-MHz ultrasonic oscillator was manufactured and the characteristics of the atomization of kerosene, stable combustion region and NOx emission on this ultrasonic atomization burner are examined. The relatively quick ignition with a few seconds delay was realized. The atomization of kerosene was obtained at the rate of 0.75 g/min, which is proportional to the time and the average kerosene droplet size, 3.1 μm, produced by 1.7 MHz ultrasonic oscillation. 0.54 kW load was obtained by using this combustor. Stable combustion was obtained around 0.7 in the equivalence ratio. The stable combustion was defined as [CO]/[CO2] < 0.002 for combustion exhaust gas. 23 ppm of low NOx emission (O2 0% base) is accomplished in the stable combustion region as it can provide the balance between both primary and secondary air flow rates.