Phase I included the development of a mathematical model, a cold flow parametric test series in a 0.746 Nm/sup 3//s GBF, and investigations of potential dust plugging problems at the inlet screen. Collection efficiencies of 99% and filter outlet loadings less than 0.0074 g/m/sup 3/ were demonstrated. The objectives of Phase II are to investigate the effects of elevated temperature and coal combustion particulate on GBF filtration performance; to update the analytical model developed in Phase I to reflect high temperature effects; to optimize filter internal configuration; to perform parametric and long duration tests to characterize the effects of filter design improvements on filtration efficiencies. Hot flow testing to date has confirmed that the GBF configured with inlet and outlet screens has exhibited a tendency for extensive and irreversible ash plugging. The potential advantages of a screenless configuration, having higher filtration efficiency, has been confirmed. This report describes the continuation of work pertinent to the development and design improvement of the GBF system, specifically addressing: (1) the development of governing equations derived for the 3-dimensional GBF mathematical model; (2) the initial results of subcontracted experiments to establish correlations of particulate capture mechanisms for use in the numerical 3-dimensional model; and (3) the design and physical modifications incorporated into the Model 4 GBF hot test setup for the final series of hot gas tests.