Severino R. Farias Neto

Transient Diffusion in Arbitrary Shape Porous Bodies: Numerical Analysis Using Boundary-Fitted Coordinates

This chapter provides information about the diffusion phenomenon (heat and mass transfer) in porous materials such as definition, classification, modeling and experiments, with particular reference to capillary-porous body with arbitrary shape. A transient three-dimensional mathematical formulation written in boundary-fitted coordinates and all numerical formalism to discretize the diffusion equation by using the finite-volume method, including grid generation and numerical analysis of the computational solution are presented. Applications to food and ceramic industries have been done with success. An optimization technique has been presented to estimation of transport properties by comparison between numerical and experimental data.

Intermittent Drying: Fundamentals, Modeling and Applications

This chapter focuses on the intermittent drying of wet porous bodies. Drying process was simulated assuming liquid diffusion as the sole mass transport mechanism and constant mass diffusion coefficient. Application has been done to ellipsoidal solids. The transient mass diffusion equation in a prolate spheroidal coordinate system was used to study the process in two-dimensional cases. Results are presented, changing the dimensionless tempering time, aspect ratio of the body and number of drying passes, by using the continuous drying process, drying rate, energy cost, drying time and quality of the product post-drying as comparison parameters.

The Effect of Droplet Diameter on the Separation of Heavy-Oil from Water Using a Hydrocyclone

The hydrocyclone is an alternative for produced water treatment in the petroleum industries, especially at offshore fields. Many parameters, such as oil droplet diameter affect the separation performance of the hydrocyclone. In this sense, the purpose of this work is study the effect of oil droplet diameter and inlet fluid on the separation efficiency of a hydrocyclone to remove dispersed heavy-oil from a water continuous stream. Results of the streamline, pressure drop, volume fraction and efficiency of separation as a function of oil droplet diameter and feed velocity are presented and analyzed.

Applying CFD in the Analysis of Heavy Oil/Water Separation Process via Hydrocyclone

In recent years most of the oil reserves discovered has been related to heavy oil reservoirs whose reserves are abundant but still show operational difficulties. This fact provoked great interest of the petroleum companies in developing new technologies for increasing the heavy oil production. Produced water generation, effluent recovered from the production wells together with oil and natural gas, is among the greatest potential factors for environmental degradation. Thus, a new scenario of the oil industry appears requiring improvement in treatment units for produced water. Among the technological improvements in the facilities, the use of hydrocyclones has been applied in the treatment of the oily water. In this sense, this study aims to investigate numerically the separation process of heavy oil from a water stream via hydrocyclone, using the computational fluid dynamics technique. In the mathematical modeling was considered a two-phase, three-dimensional, stationary, isothermal and turbulent flow. Results of streamlines, pressure and volume fraction fields of the involved phases (oil and water) into the hydrocyclone, and mechanical efficiency and pumping power of the fluids are shown and analyzed. In conclusion, it seems that with increasing fluid input velocity in the device there is an increase in pressure drop, indicating a greater pumping energy consumption of the mixture, and greatly influences the separation process efficiency.

A mathematical model for RTM process simulations in geometries with irregular shapes

Composites made by using RTM processes have attractive properties to aerospace and automotive industries. However, it is mandatory optimize all process parameters. Some mathematical models developed to predict fluid flow in porous media may be used as a support tool for laboratory studies. These models present complex sets of differential partial equations that may be solved numerically, via discretization methods. This work presents a mathematical model to predict resin and air flow in RTM processes. The finite volume method was used to discretize the equations written in boundary fitted coordinates, without the need for any front tracking algorithm. To validate the methodology, numerical results for flow front positions in rectilinear flows were compared to analytical data. The model was also employed to describe the fluid flow in geometries with arbitrary irregular boundaries.

Oily Water Treatment Using Ceramic Membrane in Presence of Swirling Flow Induced by a Tangential Inlet via CFD

In recent years, attention has been given to the processes controlling the emission of oily effluents and their environmental impact. Many industrial processes generate large volumes of water contaminated with oil, called oily waters. The oily water must be treated before its discard in order to meet the criteria established by environmental agencies (for example in Brazil, 20 mg/L). In present days, the process of separating oil/water with ceramic membranes has attracted the attention of many researchers [1,2]. In this sense, the aim of this study is to evaluate the influence of the tangential inlet shape in the oil/water separation via ceramic membranes. We use a mathematical multiphase flow model to describe the oil-water separation, based on the particle model. Here oil is the dispersed phase while water the continuous phase. To model the turbulence effect we use the RNG k-ε model. All simulations were carried out using the Ansys CFX ® commercial code. Results of streamlines and velocity, pressure and volume fraction of phase fields are present and analyzed. The numerical results indicate that no significant difference when using a circular or rectangular pipe with the same cross-sectional area.

Non-Isothermal Enhanced Recovery of Heavy Oils by Numerical Simulation

The world has been witnessing a growing interest in heavy oil fields as a result of a reduction in conventional oil reserves. In this sense, this work aims to study numerically the process of heavy oil recovering in oil reservoir via water injection. Transient three-dimensional numerical simulations, considering isothermal and non-isothermal processes, were performed using the ANSYS CFX 11 commercial code, and its effects upon the oil recovery factor evaluated. The numerical results indicated an increase of 29% (non-isothermal case) and 18% (isothermal case) in the recovery factor when water was injected on the reservoir surface as compared to the water internal injection in the reservoir.