Hydrodynamic Behavior of Biomass Micro-Particles in Counter-Flow Combustion of Dust Clouds

A mathematical model has been investigated to predict the effect of hydrodynamic forces, especially thermophoretic forces on micro organic particles in counter-flow combustion in this research. Hydrodynamic forces change the velocity and concentration of evaporative organic particles moving toward the flame and they make a particle-free distance above the flame surface. Particle evaporation creates a thrust force that affects the velocity of the particles, which can be ignored compared to other hydrodynamic forces. Also, the temperature difference between the particles, the interaction of the particles on each other is neglected.The distance between the inlet nozzle and the flame surface is divided into four zones to investigate the dynamic behavior of particles in the flame front that in each case, the dynamic particles equations are written and the effect of thermophoretic force, weight force, drag force and buoyant force are analyzed on the particles and as a result, the velocity and concentration profiles of the particles are obtained in terms of distance from the flame front at different strain rates and with different particle diameters. The particles concentration of above the flame front increases with the balance of these forces, which the increasing the particles accumulation above the flame decreases the combustibility of particles in the flame front. Then, the length of the particle-free zone is extracted under the influence of different strain rates at different temperatures. As the flame surface approaches, the temperature gradient rises and the thermophoretic force increases. Accordingly, heavier particles accumulate closer to the flame surface.

کلیدواژه ها:

Combustion ، Counter - Flow ، Biomass Dust Clouds ، Thermophoresis phenomenon