Improvement on Quantitative Measurement of Fly Ash Contents Using Laser-Induced Breakdown Spectroscopy

Contents of fly ash are important factors for the operation of coal-fired plants. Real-time monitoring of coal and fly ash such as unburned carbon in fly ash can be an indicator of the combustion conditions. Because of the strong signal intensity and the relative simplicity of the LIBS (Laser- Induced Breakdown Spectroscopy) technique, LIBS can be applicable for real-time composition measurement of coal and fly ash. This research presented here focused on the clarification of the effects of plasma temperature and coexisting materials on quantitative measurement of fly ash contents. Quantitative capability of LIBS was improved using the proposed plasma temperature correction method. The CO2 effect was also discussed to accurately evaluate unburned carbon in fly ash in exhausts. Using the results shown in this study, quantitative measurement of fly ash contents has been improved for wider applications of LIBS to practical fields.

Behaviors of Spherical and Nonspherical Particles in a Square Pipe Flow

The lattice Boltzmann method(LBM)for multicomponent immiscible fluids is applied to the simulations of solid-fluid mixture flows including spherical or nonspherical particles in a square pipe at Reynolds numbers of about 100.A spherical solid particle is modeled by a droplet with strong interfacial tension and large viscosity,and consequently there is no need to track the moving solid-liquid boundary explicitly.Nonspherical(discoid,flat discoid,and biconcave discoid)solid particles are made by applying artificial forces to the spherical droplet.It is found that the spherical particle moves straightly along a stable position between the wall and the center of the pipe(the Segr´e-Silberberg effect).On the other hand,the biconcave discoid particle moves along a periodic helical path around the center of the pipe with changing its orientation,and the radius of the helical path and the polar angle of the orientation increase as the hollow of the concave becomes large.

Lattice Boltzmann Simulations of Water Transport from the Gas Diffusion Layer to the Gas Channel in PEFC

Water management is a key to ensuring high performance and durability of polymer electrolyte fuel cell(PEFC),and it is important to understand the behavior of liquid water in PEFC.In this study,the two-phase lattice Boltzmann method is applied to the simulations of water discharge from gas diffusion layers(GDL)to gas channels.The GDL is porous media composed of carbon fibers with hydrophobic treatment,and the gas channels are hydrophilic micro-scale ducts.In the simulations,arbitrarily generated porous materials are used as the structures of the GDL.We investigate the effects of solid surface wettabilities on water distribution in the gas channels and the GDL.Moreover,the results of X-ray computed tomography images in the operating PEFC are compared with the numerical simulations,and the mechanism of the water transport in PEFC is considered.

Gas Transport Properties in Gas Diffusion Layers:A Lattice Boltzmann Study

The lattice Boltzmann method is applied to the investigations of the diffusivity and the permeability in the gas diffusion layer(GDL)of the polymer electrolyte fuel cell(PEFC).The effects of the configuration of water droplets,the porosity of the GDL,the viscosity ratio of water to air,and the surface wettability of the GDL are investigated.From the simulations under the PEFC operating conditions,it is found that the heterogeneous water network and the high porosity improve the diffusivity and the permeability,and the hydrophobic surface decreases the permeability.