Visualization study on the in-cylinder combustion temperature and soot characteristics of biodiesel

Studies on biodiesel and diesel in an electronic-control optical engine, were conducted under the same injection strategy using the high-speed photography. From the two-color technique, the soot temperature and KL factor were obtained from flame images and were used to analyze the in-cylinder flame temperature and soot characteristics of biodiesel. Results show that the luminosity, distribution area, high temperature (above 2000 K) zone and mean soot temperature of biodiesel flame of biodiesel are reduced compared to those of diesel flame. Under the same injection strategy, the in-cylinder integrated soot summation of biodiesel is less than that of diesel during the combustion period. The relationships between flame temperature and soot concentration are similar for biodiesel and diesel. Soot concentration increase with the increase of temperature from 1650 K to 2050 K, and reaches its maximum value between 1850 K and 2050 K, and then sharply reduce between 2050 K and 2150 K.