Experimental Study of Acoustic Velocity Effects on Simulated Solid Fuel Pyrolysis

An experimental study of the effect of acoustic velocity oscillations on solid fuel pyrolysis, modeled using dry ice sublimation, was performed. Use of dry ice as a solid fuel simulant allows the fluid mechanics of the problem to be separated from the combustion process. The experimental facility was designed to model solid waste pyrolysis in an acoustically excited incinerator. Dry ice was placed in a rectangular chamber in which resonant acoustic oscillations could be driven. A mean flow of air entered from one end of the chamber, and exhaust was removed from the opposite end. Flow visualization indicated that the mass transport near the dry ice surface was greatly increased when velocity oscillations were present. When the dry ice was positioned at an acoustic velocity antinode of a 160-dB standing oscillation, the sublimation rate was nearly 60% greater than without oscillation. For the conditions studied, the effects of velocity oscillations at a constant amplitude became greater as the mean velocity was increased. Comparison of the sublimation rates measured with dry ice located at acoustic velocity and pressure antinodes shows that, at constant amplitude, acoustic velocity oscillations have a much greater effect on the sublimation rate than pressure oscillations.