Coeficientes de perda de carga em valvulas e acessorios no escoamento laminar de fluidos nao-Newtonianos

Friction loss coefficients for laminar flow of xantan gum solutions (concentrations in the range of 0.1-0.5% by weight) through valves and fittings were experimentally determined. The rheological behavior, studied by means of a concentric cylinder rheometer, was pseudoplastic, being well described by the Ostwald-De Waele model with non-linear correlation coefficients (r) between 0.998 and 0.999. In the pressure drop measurements the following fittings were employed: completely open and half way open ball valve, completely open and half way open angle valve, tee used like coupling, tee used like a 90° elbow, short radius 90° elbow and coupling. The results showed that the friction loss coefficients increased with decreasing generalized Reynolds number. The friction loss coefficients could be well adjusted by a potential model, suggested by Kittredge & Rowley (1957) for Newtonian fluids, K f = A(Re g) -B, with correlation coefficients between 0.837 and 0.999.

Manejo médico y quirúrgico en pacientes con insuficiencia venosa mixta : comparación de características clínicas y hemodinámicas

La insuficiencia venosa superficial puede ser causa de insuficiencia venosa profunda, por tanto el manejo quirúrgico del sistema superficial puede mejorar la insuficiencia profunda En nuestro medio no se acostumbra a intervenir quirúrgicamente pacientes con insuficiencia venosa mixta bajo la creencia de exacerbar la enfermedad o generar complicaciones. METODOLOGIA: Se realizó un estudio retrospectivo, tomando pacientes con insuficiencia venosa mixta, entre el año 2006 y 2010, comparando parámetros hemodinámicos por duplex, y parámetros clínicos, según la clasificación CEAP, en los pacientes sometidos a cirugía convencional y en pacientes que recibieron manejo médico conservador. RESULTADOS: Se obtuvieron 45 pacientes, 65% con manejo quirúrgico y 35% manejo médico, con características sociodemograficas y comorbilidades comparables. Sin diferencia en el número de complicaciones (p=0,64), existió una mejoría en el 77% de los pacientes del grupo quirúrgico en parámetros hemodinámicos y de ningún paciente en el grupo de manejo médico, y en mejoría de ulceras activas de 83% y de 33%, respectivamente. DISCUSION: Nuestro estudio constituye una primera aproximación en la investigación en pacientes con esta patología en nuestro medio que son llevados a manejo quirúrgico. Estos resultados sugieren un posible beneficio en cuanto a los parámetros hemodinámicos venosos profundos y en las características clínicas, especialmente cuando existen ulcera activas, cuando los pacientes con insuficiencia venosa mixta son llevados a manejo quirúrgico. Sin embargo, se requieren de estudios futuros que permitan demostrar así estos resultados en nuestro medio.

Sistema de aquisição de dados para estudos de transiente de pressão e detecção de vazamentos em oleodutos

In February 2011, the National Agency of Petroleum, Natural Gas and Biofuels (ANP) has published a new Technical Rules for Handling Land Pipeline Petroleum and Natural Gas Derivatives (RTDT). Among other things, the RTDT made compulsory the use of monitoring systems and leak detection in all onshore pipelines in the country. This document provides a study on the method for detection of transient pressure. The study was conducted on a industrial duct 16" diameter and 9.8 km long. The pipeline is fully pressurized and carries a multiphase mixture of crude oil, water and natural gas. For the study, was built an infrastructure for data acquisition and validation of detection algorithms. The system was designed with SCADA architecture. Piezoresistive sensors were installed at the ends of the duct and Digital Signal Processors (DSPs) were used for sampling, storage and processing of data. The study was based on simulations of leaks through valves and search for patterns that characterize the occurrence of such phenomena

Estudo experimental da interação fluido-estrutura em um modelo de válvula de compressor de refrigeração

Pós-graduação em Engenharia Mecânica - FEIS

Estudo experimental da interação fluido-estrutura no escoamento em um difusor radial

Pós-graduação em Engenharia Mecânica - FEIS

Modelagem numérica do escoamento em válvulas automáticas de compressores pelo Método da Fronteira Imersa

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Investigação numérica e experimental do escoamento em válvulas de compressores herméticos

Pós-graduação em Engenharia Mecânica - FEIS

Análise de sistemas de máquinas térmicas em plantas de processos químicos

Pressure drop and energy efficiency of compressors in chemical plants are the focus of this study. Its objective is an analysis of possible sources of energy loss through the study of pressure loss in pipes, calculation of thermodynamic efficiency of the compressors. Important issues are raised for this analysis such as the types of compressors, the operating range of each compressor, compression types, as well as a study of accessories such as filters and valves. After studying these issues was carried out calculations of pressure drop step-bystep and with a software WIPCD. Followed by the calculation of efficiency of compressors and monthly energy cost of each compressor in operation. Finally, the study shows some suggestions for immediate improvements, changes and suggestions for possible future purchases of compressors

Simulação numérica do escoamento em difusores radiais com discos frontais fixos e móveis

Pós-graduação em Engenharia Mecânica - FEIS

Modelagem numérica do escoamento em válvulas de compressores alternativos pelo método da fronteira imersa com refinamento adaptativo

Pós-graduação em Engenharia Mecânica - FEIS