Particle effects on gas optical properties and radiation heat transfer in an MHD furnace

The effect of particles on the optical properties of the flue gas in the oxidizing zone of the furnace at the Coal Fired Flow Facility (CFFF) is being studied to determine the effect of particles on radiation heat transfer, and also to determine how particles influence line reversal temperature measurements at the Superheater Test Module (SHTM) entrance. Equilibrium chemistry calculations were performed to estimate the equilibrium amounts of condensed potassium species present in the flue gas as a function of gas temperature and K[sub 2]/S ratio. Mie scattering calculations were then performed to estimate the transmissivity across a four-foot path length for radiation at the sodium line reversal measurement wavelength, assuming that particles are present in the amounts predicted by the equilibrium chemistry calculations. The results were compared with measured line reversal transmissivity data and were found to be in reasonable agreement. Finally, a Monte Carlo technique was used to estimate the effect of particles on radiation heat transfer in the furnace. Results of these calculations indicate that radiation heat transfer from the furnace walls to the gas is increased by about 30 percent when the particles are present, as compared to the heat transfer from gas only.