The characteristics of puffing of the carbonated emulsified fuel

This paper presented the characteristics of puffing of carbonated emulsified fuel. Emulsified fuel saturated with CO2 under PCO2=92kPa and Te = 288 K and the degassed emulsified fuel were used in the experiment. An emulsified fuel droplet suspended from a thermocouple was inserted into an electric furnace. Puffing behavior was observed by using a high-speed video camera. The waiting time and the superheat temperature for the occurrence of puffing were measured. The mean waiting time of the emulsified fuel saturated with CO2 decreased by about 25% compared with that of the degassed emulsified fuel. When the degassed emulsified fuel was used, there was a peak of puffing occurrence at the superheat temperature of 60 K. When the emulsified fuel saturated with CO2 was used, there was a peak of puffing occurrence at the superheat temperature of 45 K. The superheat temperature at the peak decreased by 15 K. Puffing behavior of the carbonated emulsified fuel was more violent than that of the degassed emulsified fuel. These were because the dissolved CO2 caused a reduction in the bubble nucleation energy. Moreover, a new equation which described the waiting time for puffing was proposed. This equation was based on the assumption that puffing occurred when the inner droplet temperature increased linearly. The calculated results of the waiting time were in good agreement with the experimental ones when puffing occurred near the initial linear region.