Fluid flows in annular regions are highly relevant in the oil industry. As a result of the ever more frequent need to increase production capacity, increasingly greater flows are applied in oil wells. However, this has led to load losses along the annular borehole/shaft, which represent a significant portion of the total energy to be supplied. Hence, the determination of these losses plays an important role in the design of these units. Using Computational Fluid Dynamics (CFD), this work investigates the field of viscoplastic fluid flows in annular spaces based on analysis of the profiles of pressure drop, entrance length, axial and tangential velocities, and on the flow path prediction. These variables are usually considered relevant for an understanding of well drilling mudflow and the particles transported by it. The predictive ability of the technique utilized here was confirmed by its congruence with the experimental pressure drop data and with the literature.

The cloth cyclone is a solid-gas separation device that consists of a Lapple cyclone whose conical section has been replaced by a conical filtering wall. The present research was undertaken with the aim of examining the influence of a conical filtering section made of three different materials on the performance of a Lapple design cyclone. The overall efficiency and pressure drops of the cloth cyclone and a conventional one were compared. The effect of the filtering medium on the behavior of the cyclone was also evaluated using an equation that correlates the cut size diameter with the operational conditions, the properties of the gas-solid system and the resistance of the filtering medium. The experimental results demonstrated that the overall efficiency of the conventional cyclone was similar to that of the proposed device, with the latter displaying a reduction in pressure drop. Consequently, energy costs are lowered when cloth cyclones are used.

The aim of this work was to analyze the main equilibrium equations used for grains to find the best way to represent the equilibrium conditions between lentil and air. The experimental study was based on the static method using saturated salt solutions. We developed criteria for distinguish between some existing equations used for grains. To distinguishing between these equations we explored some nonlinearity measures. The results obtained showed that the Halsey modified equation was the best model in terms of nonsignificance for bias and nonlinearity measures.