Studying the diesel flame structure in superheated water vapor jets by using IR thermography

The use of water and water vapor in fuel combustion positively affects both environment parameters and the device stability. This is effective in the disposal of low-grade liquid hydrocarbons. The work is devoted to the experimental study of thermal characteristics of flame (effective emissivity and temperature) during the combustion of liquid fuel sprayed by a superheated steam jet, which is to supplement information on the steam effect on key parameters of fuel combustion. The measurements were carried out in a new burner at different operating parameters (fuel and steam mass flow rates and steam temperatures). During the first step of the research, high-quality liquid hydrocarbon (diesel fuel) is chosen, which is usually used in burners. In the study, we used a JADE J530SB FLIR thermal imaging camera and a type B platinum-rhodium-platinum-rhodium thermocouple. Instantaneous and average temperature fields were obtained; the peak flame temperature attained 1440 degrees C. It is found that the effective emissivity value (epsilon = 0.3 divided by 0.4) depends on the steam and fuel flow rate that is connected with the completeness of fuel combustion and soot concentration in the flame. An increase in the steam flow rate decreases the flame temperature by more than 200 degrees C, which prevents the formation of thermal nitrogen oxides. The thermal imaging measurements well agree with thermocouple data (within 9%).