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The spatial distribution of neutral gas temperature and total pressure have been measured for pure N 2 , He/5%N 2 and Ar/5%N 2 in an inductively coupled plasma (ICP) reactor, and a significant rise in the neutral gas temperature has been observed. When thermal transpiration is used to correct total pressure measurements, the total pressure remains constant regardless of the plasma condition. Neutral pressure is depleted due to the pressure balance when the plasma pressure (mainly electron pressure) becomes comparable to the neutral pressure in high density plasma. Since the neutral gas follows the ideal gas law, the neutral gas density profile was obtained from the neutral gas temperature and the corrected neutral pressure measurements. The results show that the neutral gas density at the centre of the plasma chamber (factor of 2-4×) decreases significantly in the presence of a plasma discharge. Significant spatial variation in neutral gas uniformity occurs in such plasmas due to neutral gas heating and pressure balance.

The velocity distribution function for helium in translational nonequilibrium in hypersonic free jet expansions has been investigated with an electron beam fluorescence technique. A unique computer controlled Fabry-Perot interferometer and data acquisition system has been used to observe the 5015.67 Å radiation from the 31 P-21 S transition in helium. From the spectral structure, the Doppler broadening and shift of the line due to the velocity distribution function can be determined. With this technique parallel and perpendicular gas kinetic temperatures, mean flow velocity, and relative density measurements were made along the centerline of the free jet, from near equilibrium conditions through the midpoint of transition (T‖/T⊥ = 2.0). A comparison with kinetic theory predictions of the temperatures and velocity distribution functions indicate that the adoption of the ellipsoidal model, although sufficient for fitting the measured distribution function, is inadequate for determining the parallel temperature. The experimental data have been compared with a Navier-Stokes theory, with moment solutions of the Boltzmann equation, and a rarefication parameter suggested from previous Monte Carlo calculations. Determination of an effective hardsphere diameter from the experimental data is also presented.

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h i g h l i g h t sCFD simulation of biomass gasification in a dual fluidized-bed. The CFD model predicts the gas composition and the reactor temperature distribution. The CFD model has been validated by experimental data. The effects of the particle size distribution and drag models have been investigated. a r t i c l e i n f o t r a c tA three-dimensional CFD model was developed to simulate the full-loop of a dual fluidized-bed biomass gasification system consisting of a gasifier, a combustor, a cyclone separator, and a loop-seal. This fullloop simulation includes the chemical kinetic modeling of biomass drying and pyrolysis, heterogeneous char reactions, and homogeneous gas-phase reactions. In the model, the gas phase is described using Large Eddy Simulation (LES) and the particle phase is described with the Multiphase Particle-In-Cell (MP-PIC) method. The simulation was performed using the GPU-accelerated computing and the simulation results were compared with the gas composition and temperature measurements from a pilot-scale biomass gasification power plant (1 MW th , 6 tons biomass/day). The independence of the accuracy of the model on mesh resolution and computational particle number was determined. The impacts of the particle size distributions (PSD) and drag models on the reactive flows were also investigated.