Preventive Program for Small Bore Piping Failure At Gas Processing Plant

This project is to investigate internal erosion effect at elbow and tee joint small bore piping. This is done by using the Computational Fluid Dynamic (CFD) analysis to validate the actual case study. By creating the models and then simulating with CFD, it is found that the failure occurred at the elbow pipe and tee joint pipe as the pressure concentration occurred there

Flow system modeling with applications to fuel cell systems

Fuel cell systems have garnered much attention recently as a possible source of clean, efficient energy. These systems are presently being designed in various arrangements to combine the use of fuel cells with other efficient power producing devices such as gas turbines, producing a system which is more efficient than either the fuel cell or gas turbine alone. The accurate modeling of these types of systems is an important contribution to the increasing development of such technologies. Of particular interest is the transient behavior of these systems, including the flow and thermal behavior of the air and fuel used. The contribution of this work is the development of a numerical, one-dimensional, variable-area duct model to predict the transient flow and thermal behavior of gasses moving through the system. Additional transient models for plenum, tee, and elbow components are created, and these parts are connected with the duct model to perform simulations of simple flow systems. Some thermal and flow characteristics of these systems are analyzed and discussed. As a verification of the models created, a portion of an actual fuel cell system is modeled and the results are compared with experimental data

Golpe de ariete polifásico : modelado, experimentos e simulación

[Abstract] This thesis deals with the experimental and numerical analysis of the water hammer phenomenon generated by the discharge of a pressurized liquid into a pipeline kept under vacuum conditions. This ow configuration induces several multiphase phenomena such as cavitation and gas desorption that cannot be ignored in the water hammer behavior. The motivation of this research work comes from the liquid propulsion systems used in spacecrafts, which can undergo uid hammer effects threatening the system integrity. Fluid hammer can be particularly adverse during the priming phase, which involves the fast opening of an isolation valve to fill the system with liquid propellant. Due to the initial vacuum conditions in the pipeline system, the water hammer taking place during priming may involve multiphase phenomena, such as cavitation and desorption of a non-condensable gas, which may affect the pressure surges produced in the lines. Even though this ow behavior is known, only few studies model the spacecraft hardware configuration, and a proper characterization of the two-phase ow is still missing. The creation of a reliable database and the physical understanding of the water hammer behavior in propulsion systems are mandatory to improve the physical models implemented in the numerical codes used to simulate this ow configuration. For that purpose, an experimental facility modeling a spacecraft propulsion system has been designed, in which the physical phenomena taking place during priming are generated under controlled conditions in the laboratory using inert uids. An extended experimental campaign was performed on the installation, aiming at analyzing the effect of various working parameters on the uid hammer behavior, such as the initial pressure in the line, liquid saturation with the pressurant gas, liquid properties and pipe configuration. The in uence of the desorbed gas during water hammer occurrence is found to have a great importance on the whole process, due to the added compressibility and lower speed of sound by an increasing amount of non-condensable gas in the liquid + gas mixture. This results in lower pressure levels and faster pressure peaks attenuation, compared to uids without desorption. The two-phase ow was characterized by means of ow visualization of the liquid front at the location where the uid hammer is generated. The front arrival was found to be preceded by a foamy mixture of liquid, vapor and non-condensable gas, and the pressure wave re ected at the tank may induce the liquid column separation at the bottom end. While column separation takes place, the successive pressure peaks are generated by the impact of the column back against the bottom end. The resulting experimental database is then confronted to the predictions of the 1D numerical code EcosimPro/ESPSS used to assess the propulsion system designs. Simulations are performed with the ow configuration described before, modeling the experimental facility. The comparison of the numerical results against the experimental data shows that aspects such as speed of sound computation with a dissolved gas and friction modeling need to be improved.[Resumen] Esta tesis presenta un estudio experimental y numérico del fenómeno de golpe de ariete generado por la descarga de un líquido presurizado en una conducción bajo condiciones de vacío. Esta configuración de ujo induce varios fenómenos multifásicos, tales como cavitación y desorción de gases no condensables, que no pueden ser ignorados en el análisis del problema. La motivación de este trabajo de investigación tiene su origen en los sistemas de propulsión con combustibles líquidos utilizados en aplicaciones aeroespaciales, donde el fenómeno de golpe de ariete y el incremento de presión ocasionado puede afectar la integridad del sistema. El golpe de ariete es particularmente adverso durante la fase de cebado, donde la apertura rápida de una válvula de aislamiento permite el llenado de las líneas de combustible, las cuales se encuentran inicialmente al vacío. Debido a esto, junto al fenómeno de golpe de ariete también tiene lugar la cavitación del uido y la desorción de un gas no condensable, los cuales afectan a los incrementos de presión que se producen en las líneas. A pesar de que todos estos fenómenos han sido ampliamente tratados en la literatura científica, existen muy pocos estudios que traten la configuración de ujo descrita y que aborden todos los fenómenos multifásicos ocasionados de forma simultánea. Es por ello que la creación de una extensa base de datos, con las condiciones experimentales bien definidas, es una necesidad para validar y mejorar los modelos físicos implementados en los códigos numéricos, los cuales se utilizan para evaluar el comportamiento de los sistemas de propulsión durante la fase de diseño. Para tal fin, se ha diseñado una instalación experimental que reproduce un sistema de propulsión, de forma que todos los fenómenos físicos que tienen lugar durante el cebado del combustible se generan en el laboratorio bajo condiciones controladas. El estudio experimental llevado a cabo ha permitido analizar el efecto de diversos parámetros de trabajo en el comportamiento del golpe de ariete, tales como la presión inicial de vacío en la línea, saturación del líquido con el gas presurizante, propiedades del líquido y configuración de la conducción. Los resultados muestran como la desorción del gas no condensable afecta de forma significativa el comportamiento del uido durante el golpe de ariete, debido al incremento de compresibilidad y la reducción de la velocidad del frente de onda al aumentar la presencia de gas en la mezcla bifásica. Esto se traduce en menores incrementos de presión y atenuación más rápida de los picos de presión, en comparaci ón con el mismo uido bajo condiciones donde la desorción no tiene lugar. La visualización del ujo allí donde se genera el golpe de ariete ha permitido caracterizar el comportamiento bifásico del uido. El avance del frente líquido en la línea está precedido por una mezcla multifásica de líquido, vapor y gas no condensable, y las ondas de expansión pueden inducir la separación de la columna líquida en el extremo cerrado de la conducción donde impacta el uido. Siempre que la separación de columna tenga lugar, los sucesivos picos de presión se generan por el impacto de la columna líquida contra el extremo cerrado de la línea tras la separación. La base de datos experimental resultante se ha comparado con las predicciones del código numérico 1D EcosimPro/ESPSS simulando la configuración experimental. La comparación de los resultados numéricos con los datos experimentales muestran que es necesario reformular el cálculo de la velocidad del frente de onda cuando existe una fase gaseosa disuelta en el volumen líquido. Además, es preciso incluir en el código un modelo de fricción no estacionario que mejore las predicciones del modelo de fricción quasi-estacionario utilizado actualmente.[Resumo] Esta tese presenta un estudo experimental e numérico do fenómeno de golpe de ariete xerado pola descarga dun líquido presurizado nunha condución baixo condicións de baleiro. Esta configuración de uxo induce varios fenómenos multif ásicos, tales como cavitación e desorción de gases non condensables, que non poden ser ignorados na análise do problema. A motivación deste traballo de investigación ten a súa orixe nos sistemas de propulsión con combustibles líquidos utilizados en aplicacións aeroespaciais, onde o fenómeno de golpe de ariete e o incremento de presión ocasionado pode afectar a integridade do sistema. O golpe de ariete é particularmente adverso durante a fase de cebado, onde a apertura rápida dunha válvula de illamento permite a enchedura das liñas de combustible, as cales se encontran inicialmente ao baleiro. Debido a isto, xunto ao fenómeno de golpe de ariete tamén ten lugar a cavitación do fluído e a desorción dun gas non condensable, os cales afectan aos incrementos de presión que se producen nas liñas. A pesar de que todos estes fenómenos foron amplamente tratados na literatura científica, existen moi poucos estudos que traten a configuración de uxo descrita e que aborden todos os fenómenos multif ásicos ocasionados de forma simultánea. É por iso que a creación dunha extensa base de datos, coas condicións experimentais ben definidas, é unha necesidade para validar e mellorar os modelos físicos implementar nos códigos numéricos, os cales se utilizan para avaliar o comportamento dos sistemas de propulsión durante a fase de deseño. Para tal fin, deseñouse unha instalación experimental que reproduce un sistema de propulsión, de forma que todos os fenómenos físicos que teñen lugar durante o cebado do combustible se xeran no laboratorio baixo condicións controladas. O estudo experimental levado a cabo permitiu analizar o efecto de diversos parámetros de traballo no comportamento do golpe de ariete, tales como a presión inicial de baleiro na liña, saturación do líquido co gas presurizante, propiedades do líquido e configuración da condución. Os resultados mostran como a desorción do gas non condensable afecta de forma significativa o comportamento do fluído durante o golpe de ariete, debido ao incremento de compresibilidade e a redución da velocidade da fronte de onda ao aumentar a presenza de gas na mestura bifásica. Isto tradúcese en menores incrementos de presión e atenuación máis rápida dos picos de presión, en comparación co mesmo fluído baixo condicións onde a desorción non ten lugar. A visualización do uxo alí onde se xera o golpe de ariete permitiu caracteri zar o comportamento bifásico do fluído. O avance da fronte líquida na liña está precedido por unha mestura multifásica de líquido, vapor e gas non condensable, e as ondas de expansión poden inducir a separación da columna líquida no extremo pechado da condución onde impacta o fluído. Sempre que a separación de columna teña lugar, os sucesivos picos de presión xéranse polo impacto da columna líquida contra o extremo pechado da liña tras a separación. A base de datos experimental resultante comparouse coas predicións do código numérico 1D EcosimPro/ESPSS simulando a configuración experimental. A comparaci ón dos resultados numéricos cos datos experimentais mostran que é necesario reformular o cálculo da velocidade da fronte de onda cando existe unha fase gasosa disolta no volume líquido. Ademais, é preciso incluír no código un modelo de fricción non estacionario que mellore as predicións do modelo de fricción quasi-estacionario utilizado actualmente

Investigation and modeling of space shuttle main engine shutdown transient chugging

The space shuttle main engines experience a low frequency pressure pulsation in both the fuel and oxidizer preburners during the shutdown transient. This pressure pulsation, called chugging, has been linked to undesirable bearing loads and possible damage to the spark ignitor supply piping for the fuel preburner. The problem is briefly described and a model is proposed that includes: (1) a transient stirred tank reactor model for the combustion chamber, (2) a resistance capacitance model for the supply piping and (3) purge gas/liquid oxygen interface tracking

Gas-Liquid Separation in T-Junction

T-junctions are widely used in piping network for distributing multiphase flows, especially in oil and gas industries. Mal-distribution of the phases flowing through a T-junction poses a challenge in maintaining homogenous splitting across a T-junction at the same time, a potential as a simple, compact partial phase separator. However, the behavior of two-phase flow complicates the process of understanding the phenomena as there are many inter-related parameters that influences the mal-distribution. In order to seriously consider T-junction as a partial phase separator, its geometry and operating condition that for efficient separation must be identified. This project aims to identify the geometric and operating conditions effects on the separation efficiency of a T-junction in terms of gas fraction in branch arm. The concerned parameters under this study are the operating pressure, oil flow rate, GOR, and arms’ length of the T-junction. OLGA Multiphase Simulator is used to model the T-junction for the parametric study. The findings conclude that operating pressure as the most influential parameter in ensuring efficient separation. At the end of this project, sufficient amount of data is collected and the phenomenon of phase mal-distribution when a two-phase mixture passes through a T-junctions is well understood. Hence, redefined the potential of T-junction as a simple, cost saving, passive partial separator for separation process in the petroleum industr

Pharmaceutical water systems: a thermal-fluid analysis of pipe dead-legs

The most commonly used technique for flow exchange, fluid isolation and removal in pharmaceutical water systems, is the installation of a branch tee with a conventional two-way outlet port valve. This however can create a stagnant or “dead-leg” zone, which is particularly hazardous as bacteria can accumulate and contaminate the entire water system. This project has involved the study of the thermal and fluid dynamics considerations within pipe dead-legs and their impact on high purity water systems. A detailed literature review of the technology surrounding pharmaceutical water systems was carried out to set the background for the analysis of pipe dead-legs. An experimental test rig was designed and constructed to represent a typical single loop water system incorporating a dead-leg test section. Results were obtained for a 6d, 4d and 2d branch tee configuration under dead-leg flow conditions. The effect of the main pipe loop velocity and temperature on the dead-leg end temperature was investigated. Determination of the temperature distribution along the axis of the dead-leg branch under steady state conditions was also investigated. It was shown that the maximum dead-leg end temperature increased for an increase in loop velocity for each configuration. Reducing the dead-leg length from a 6d to a 4d and 2d configuration respectively was shown to significantly increase the dead-leg end temperature. It was found that a zone of uniform temperature and a temperature decay region were present in each branch configuration respectively. It was shown that stagnant fluid was present at the end o f the dead-leg for the 6d and 4d configurations. The 2d dead-leg was found to be the most effective configuration to achieve full loop temperature penetration and mixing of the dead-leg fluid. The 6d rule was shown to be inadequate for both fluid mixing and loop temperature penetration

COMPUTATIONAL FLUID DYNAMICS STUDY ON T-JUNCTION SEPARATOR FOR LIQUID-GAS SEPARATION

The separation of liquid-gas flow is an essential part of many industrial processes and the occurrence of multiphase flow in the petroleum industry is very common in the production and processing facilities of hydrocarbon. These separations are performed in large separator vessels under the effect of gravity containing large inventories of potentially flammable and/or toxic materials. The application of a simple defined partial phase separator (T-junction) would produce two streams, one rich in gas and the other rich in liquid. This would be beneficial to the petroleum industry especially in offshore oil platforms where safety, space, weight and cost are highly emphasized. Therefore, this project presents the study of fluid model on liquid-gas flow separation at a horizontal T-junction. Simulations were analyzed using numerical computational fluid dynamics (CFD) software. Numerical results of pressure profile and volume fraction of phases for fluid models are presented and analyzed to propose a new or improved T-junction design with better separation efficiency

CFD analysis of pharmaceutical water distribution systems: T-junctions

High pure water systems are used in pharmaceutical and chemical industries. Deadlegs are generally found at points of use in distribution systems. The FDA suggests that the 6D rule is sufficient to help prevent microbial contamination, due to stagnant water within the dead leg. However, more recently, industrial experts are designing systems with dead legs limited to 3D or less. The aim of this study is to examine the effects of entry length, drop loop bends, dead-leg length and mainflow velocity on flow patterns within a branch of a 50:50 mm equal tee. A 2D CFD analysis was carried out on a range of dead-leg configurations and the resulting data presented highlight the overall flow patterns with each branch. A rig was modified to carry out the dye injection tests, to verify CFD results. It was found that the entry length had a little effect on the flow velocity of the deadleg branch. However, when a bend was incorporated in the system, the entry length increase improved the flow patterns of all dead-leg branches. Different combinations of mainflow velocities, dead-leg lengths and length extensions were evaluated to investigate their effect on the flow pattern. It was observed that high mainflow velocities yielded better flow patterns in 2DL and 4DL when compared with 6DL. High mainflow velocities resulted in good flow patterns at only 2DL. At low mainflow velocities, 4DL and 6DL had better flow patterns compared with 2DL. Increasing the length of the extension resulted in better flow patterns in 6DL. At both, high and low mainflow velocities, 4DL sowed a reasonable flow pattern in the branch. Flow visualization studies were performed as well as a CFD simulation. The results of both studies were in good agreement in the case of 4DL branch length. However, for 2DL, an accelerated dye dispersion was observed, suggesting a higher fluid exchange between the mainstream flow and the branch

Vortexing Off A Common Suction Header

This project is the first iteration of a testing rig to determine the critical submergence of a vortex off a main suction header. The rig was designed with supplies purchased and provided by PG&E, including 4-6” schedule 40 PVC pipe and fittings, a large water tank, a pump, and a flowmeter. PG&E at Diablo Canyon Power Plant presented their problem to the Cal Poly Mechanical Engineering Senior Project class, and three mechanical engineers took up the project. The following report details the ideation, design, build, and test processes used during the 2016-17 academic year to create the vortex testing rig. We determined through testing that the location of hydraulic jump can be influenced by how open or closed the branch line valve was, which in turn influenced when gas ingestion to the pump occurred