Study on temperature variation and pulsation frequency of diesel-wetted wood powder fire with different fuel component ratios and burner diameters

Abstract

Temperature variation and flame pulsation behavior of diesel-wetted wood powder fire were experimentally studied. Fuel component ratios (the mass ratio of diesel to wood powder) and burner diameters were considered. The results show that due to the difference between flash/pyrolysis point of diesel and wood powder, the fuel component that mainly combusts transits from diesel to wood powder gradually. So after ignition, the temperature rises rapidly to 600 °C–800 °C, before getting stable within 200 °C–400 °C. The combustion were divided into three stages: rapid burning, transition stage and steady burning. In steady stage, cases with higher fuel component ratio and larger burner sizes have higher temperature. Transition of fuel component that mainly combusts also caused mass loss rate to decrease, which induced the flame shape to change. Generally, flame pulsation frequency is inversely proportional to burner diameter. However, with the reduction of mass loss rate, flame pulsation frequency decreases slightly. For smaller burner size (D ≤ 7 cm) and lower fuel component ratio (φ = 0.5), flame without pulsation could be observed. A dimensionless correlation regarding flame pulsation frequency for this kind of fire was proposed.

Keywords

• Temperature variation
• Flame pulsation frequency
• Diesel-wetted wood powder fire