Enivaldo Santos Barbosa

Resin Transfer Molding Process: Fundamentals, Numerical Computation and Experiments

Resin Transfer Molding (RTM) is one of the most widely known composite manufacturing technique of the liquid molding family, being extensively studied and used to obtain advanced composite materials comprised of fibers embedded in a thermoset polymer matrix. The fibrous reinforcement is considered a porous medium regarding its infiltration by the polymer resin. In this sense, this chapter aims to briefly discuss multiphase flow and heat transfer theory in RTM process, focusing on a multifluid model and the Control Volume/Finite Element (CV/FE) method. Finally, computational analysis was developed on the basis of ANSYS CFX® and PAM-RTM commercial software’s for the investigation of the fluid flow in RTM composite molding. In order to show the versatility and performance of the commercial codes, RTM experiments were carried under distinct injection pressure and fiber volume fraction conditions using plain-weave glass fiber cloth as the porous media. The transient numerical simulations provided information about volume fraction, pressure and velocity distribution of the phases (resin and air) inside the porous media.

Drying of Ceramic Hollow Bricks in an Industrial Tunnel Dryer: A Finite Volume Analysis

This paper aims to study the drying of industrial hollow bricks in a tunnel dryer cross flow type. The theoretical model is based on mass and energy conservation equations applied to air and product. To validate the methodology, numerical and experimental results for the moisture content and the temperature of brick during the drying in an industrial scale are compared and a good correlation was obtained. Results of moisture content and temperature of the product, and temperature, relative humidity and absolute humidity of drying air as a function of drying time and position in the dryer are presented and analyzed.

GBI Method: A Powerful Technique to Study Drying of Complex Shape Solids

This chapter briefly focuses on the theory and applications of drying process (heat and mass transfer) with particular reference to arbitrarily-shaped wet capillary-porous bodies. Here, a modeling based on the liquid diffusion theory and the mathematical formalism to obtain the exact solution of the governing equation via Galerkin-based integral method are presented. The model considers constant thermo-physical properties and convective boundary conditions at the surface of the solid. Applications have been done to different solids of revolution and wheat grain. Predicted results of the average moisture content, average temperature, and moisture content and temperature distributions within the porous solids are presented and discussed, and for particular situations they are compared with experimental drying data.

Multiphase Flow and Heat Transfer in Risers

Multiphase flows commonly occur in the production and transportation of oil, natural gas and water. In this type of flow, the phases can flow in different spatial configurations disposed inside the pipe, so called multiphase flow patterns. The identification of flow patterns and the determination of the pressure drop along the pipe lines for different volumetric flows are important parameters for management and control of production. In this sense, this work proposes to numerically investigate the non-isothermal multiphase flow of a stream of ultraviscous heavy oils containing water and natural gas in submerged risers (catenary) via numerical simulation (ANSYS CFX 11.0). Results of the pressure, volumetric fractions and temperature distributions are presented and analyzed. Numerical results show that the heat transfer was more pronounced when using the largest volume fraction of gas phases.

Numerical Evaluation of the Pressure Drop in Multiphase Flow of the Catenary Riser with the Presence of Leakage

The growing demand for oil brings the need for discovery of deeper reservoirs, especially of ultra-deepwater reservoirs. Thus, production in marine systems using components such as risers (flexible or rigid pipes) has been the focus of many studies in different areas. These ducts are used in the transportation of multiphase fluids (oil, water and gas) produced from the oil well located on the seabed to the platform surface. Due to the extreme conditions present in the offshore fields of production, the equipments that transport produced fluids operate close to their limits. So eventually, the flexible pipes may have structural integrity faults like leaks, which can cause production losses, accidents with victims and environmental disasters. The leak depends of a number of properties or parameters measured at the site of the leak, for example, integrity of the pipe material, release of fluids and noise emission characteristics or manifestation of some other type of signal behavior, variation of pressure drops close to the leak, among others. There are a variety of techniques available for detecting leaks, among which there is the mathematical modeling approach using computational techniques. In this context, this paper aims to study the fluid dynamics of a transient multiphase flow in a catenary riser in the presence of leakage. Herein a 3D Eulerian-Eulerian model was applied, including the turbulent model (RNG k-ε), using the commercial package ANSYS CFX® 15 to perform all simulations. The numerical results of velocity, volume fraction and pressure of the involved phases are presented and discussed.

Three-phase flow (water, oil and gas) in a vertical circular cylindrical duct with leaks: A theoretical study

This article describes the fluid dynamic behavior of a three-phase flow (water-oil-natural gas) in a vertical pipe with or without leakage. The studied pipe has 8 meters in length, circular cross-section with 25 cm in diameter and a leak, which hole has a circular shape with 10mm diameter located in the center of pipe. The conservation equations of mass, momentum and energy for each phase (continuous phase - oil, dispersed phases - gas and water) were numerically solved using ANSYS CFX software, in which the Eulerian-Eulerian model and the RNG - turbulence model were applied. Results of the pressure, velocity, temperature and volume fraction distributions of the involved phases are present and analyzed.

Separation Process by Porous Membranes: A Numerical Investigation

A major problem associated with the membrane separation processes is the permeate flux drop, limiting the widespread of industrial application of this process. This occurs due to the accumulation of solute concentration near the membrane surface. An exact quantification of the concentration polarization as a function of process conditions is essential to estimate the system performance satisfactorily. In this sense, this work aims to predict the behavior of the concentration polarization boundary layer along the length of a permeable tubular membrane, over various operation conditions. The numerical solution of the Navier-Stokes equation, coupled to Darcys and mass transfer equations, is obtained by the commercial software ANSYS CFX 12, considering a two-dimensional computational domain. The study evaluates the effects of axial Reynolds and Schmidt numbers on the concentration polarization boundary layer thickness during the cross-flow filtration process. Numerical results have shown that the mathematical model is able to predict the formation and growth of the concentration polarization boundary layer along the length of the tubular membrane.