A. G. B. de Lima

Heat and Mass Transfer in Porous Materials with Complex Geometry: Fundamentals and Applications

This chapter provides information related to simultaneous heat and mass transfer and dimension variations in unsaturated porous bodies of arbitrary shape during transient problems. Two mathematical approaches are presented and discussed: lumped and distributed-parameters models. Here, applications have been given to some engineering processes (cooling, heating and drying). A two-dimensional distributed model written in a orthogonal curvilinear coordinate system and which assumes the pure diffusion as the sole mechanism of heat and moisture transport within the solid is applied to ellipsoidal porous bodies (prolate spheroid). A lumped-parameter model written in any coordinate system which includes effects such as shape of the body, heat and mass generation, evaporation and convection is presented, and analytical solution of the governing equations, limitations of the modeling and general theoretical results are discussed.

Secagem e retração volumétrica de tijolos cerâmicos maciços e vazados: uma investigação teórica e experimental

The ceramic industry presents industrial processes with a large consumption of energy and high environmental impact. These industries are developing products of low quality due to inadequate drying and firing processes. Therefore, the purpose of this study is to contribute for the improvement of drying process by presenting a drying experimental study of the samples of clay for red ceramics (hollow and solid bricks) with different dimensions and initial moisture contents. In the drying processes, several air temperatures and air relative humidity were used, and thus several curves of the drying kinetics and volumetric retraction are shown and analyzed. Mathematical equations for predict lost of water and dimension variations during the process were obtained. It was verified that drying process takes place in the falling rate period and shrinkage happens in two distinct periods.

Influence of Geometric Parameters of the Hydrocyclone and Sand Concentration on the Water/Sand/Heavy-Oil Separation Process: Modeling and Simulation

In the oil exploitation, produced fluids are composed of oil, gas, water and sand (depending on the reservoir location). The presence of sand in flow oil leads to several industrial problems for example: erosion and accumulation in valves and pipeline. Thus, it is necessary to stop production for manual cleaning of equipments and pipes. These facts have attracted attention of academic and industrial areas, enabling the appearing of new technologies or improvement of the water/oil/sand separation process. One equipment that has been used to promote phase separation is the hydrocyclone due to high performance of separation and required low cost to installation and maintenance. In this sense, the purpose of this work is to study numerically the effect of geometric parameters (vortex finder diameter) of the hydrocyclone and sand concentration on the inlet fluid separation process. A numerical solution of the governing equations was obtained by the ANSYS CFX-11 commercial code. Results of the streamlines, pressure drop and separation efficiency on the hydrocyclone are presented and analyzed. It was observed that the particles concentration and geometry affect the separation efficiency of the hydrocyclone.