Pyrolysis gas jets out from the surface of a solid fuel particle when heated. This study experimentally observes the occurrence of gas jets？from heated solid fuel particles. Results reveal a local gas jet occurs from the particle’s surface when its temperature reaches the point at which a pyrolysis reaction occurs. To investigate the influence of the gas jet on particle motion, a numerical simulation of the uniform flow around a spherical particle with a nonuniform outflow or high surface temperature is conducted, and the drag force acting on the spherical particle is estimated. In the numerical study, the magnitude of the outflow velocity, direction of outflow, and Rayleigh number,？i.e., particle surface temperature, are altered, and outflow velocities and the Rayleigh number are set based on the experiment. The drag coefficient is found to decrease when an outflow occurs in the direction against the mainstream; this drag coefficient at a higher Rayleigh number is slightly higher than that at a Rayleigh number of zero.
Gomez, C.O. and Vastola, F.J. (1985) Ignition and Combustion of Single Coal and Char Particles. Fuel, 64, 558-563. https://doi.org/10.1016/0016-2361(85)90093-6
Solomon, P.R., Serio, M.A. and Suuberg, E.M. (1992) Coal Pyrolysis: Experiments, Kinetic rates and Mechanisms. Progress in Energy and Combustion Science, 18, 133-220. https://doi.org/10.1016/0360-1285(92)90021-R
Seebauer, V., Petek, J. and Staudinger, G. (1997) Effects of Particle Size, Heating Rate and Pressure on Measurement of Pyrolysis Kinetics by Thermogravimetric Analysis. Fuel, 76, 1277-1282. https://doi.org/10.1016/S0016-2361(97)00106-3
Kok, M.V., Ozbas, E., Karacan, O. and Hicyilmaz, C. (1998) Effect of Particle Size on Coal Pyrolysis. Journal of Analytical and Applied Pyrolysis, 45, 103-110.
https://doi.org/10.1016/S0165-2370(98)00063-1
Zajdlík, R., Jelemensky, L’., Remiarová, B. and Markos, J. (2001) Experimental and Modelling Investigations of Single Coal Particle Combustion. Chemical Engineering Sciences, 56, 1355-1361. https://doi.org/10.1016/S0009-2509(00)00358-4
Bejarano, P.A. and Levendis, Y.A. (2008) Single-Coal-Particle Combustion in O2/N2 and O2/CO2 Environments. Combustion and Flame, 153, 270-287.
https://doi.org/10.1016/j.combustflame.2007.10.022
Franchetti, B.M., Cavallo Marincola, F., Navarro-Martinez, S. and Kempf, A.M. (2013) Large Eddy Simulation of a Pulverized Coal Jet Flame. Proceedings of the Combustion Institute, 34, 2419-2426. https://doi.org/10.1016/j.proci.2012.07.056
Warzecha, P. and Boguslawski, A. (2014) LES and RANS Modeling of Pulverized Coal Combustion in Swirl Burner for Air and Oxy-Combustion Technologies. Energy, 66, 732-743. https://doi.org/10.1016/j.energy.2013.12.015
Haider, A. and Levenspiel, O. (1989) Drag Coefficient and Terminal Velocity of Spherical and Nonspherical Particles. Powder Technology, 58, 63-70.
https://doi.org/10.1016/0032-5910(89)80008-7
Holzer, A. and Sommerfeld, M. (2009) Lattice Boltzmann Simulations to Determine Drag, Lift and Torque Acting on Non-Spherical Particles. Computers & Fluids, 38, 572-589. https://doi.org/10.1016/j.compfluid.2008.06.001
Zastawny, M., Mallouppas, G., Zhao, F. and Wachem, B. (2012) Derivation of Drag and Lift Force and Torque Coefficients for Non-spherical Particles in Flows. International Journal of Multiphase Flow, 39, 227-239.
https://doi.org/10.1016/j.ijmultiphaseflow.2011.09.004
Lee, H. and Balachandar, S. (2010) Drag and Lift Forces on a Spherical Particle Moving on a Wall in a Shear Flow at Finite Re. Journal of Fluid Mechanics, 657, 89-125. https://doi.org/10.1017/S0022112010001382
Kurose, R., Makino, H., Komori, S., Nakamura, M., Akamatsu, F. and Katsuki, M. (2003) Effects of Outflow from the Surface of a Sphere on Drag, Shear Lift, and Scalar Diffusion. Physics of Fluids, 15, 2338-2351. https://doi.org/10.1063/1.1591770
Katoshevski, D., Zhao, B., Ziskind, G. and Bar-Ziv, E. (2001) Experimental Study of the Drag Force Acting on a Heated Particle. Journal of Aerosol Science, 32, 73-86.
https://doi.org/10.1016/S0021-8502(00)00057-4
