Carbonate acidizing: Modeling, analysis, and characterization of wormhole formation and propagation

This paper presented the recent development of heat transfer enhancement through facing step and corrugated channels. Numerical simulation findings of the convective heat transfer with and without nanofluids have been investigated. The experimental trials to augment heat transfer in the facing step and corrugated channels by using conventional fluids and nanofluids are reported. Both of the laminar and turbulent flows through facing step and corrugated channels are introduced. There were good agreements among numerical and experimental studies to augment heat transfer. The significant applications of the engineering field have led many investigators to use nanofluid in the heat exchanger for heat transfer augmentation. New design of the corrugated facing step channel to enhance heat transfer is being proposed. The utilization of nanofluids will be useful in the new channel to enhance the heat transfer numerically and experimentally. The heat transfer enhancement was estimated up to 60% when using nanofluid in the facing step channel. Regression equations can correlate relationships among the responses and the input parameters. It is needed to compare the dimensions of the new channels that includes height of step, height of corrugated and shape of corrugated that might give an optimum heat transfer enhancement with a slight friction factor.

Review of forced convection nanofluids through corrugated facing step

https://file.scirp.org/pdf/ENG20120400009_32908670.pdf

CFD Analysis of Single and Multiphase Flow Characteristics in Elbow

Computational fluid dynamics (CFD) analysis was performed in four different 90 degree elbows with air-water two-phase flows. The inside diameters of the elbows were 6.35mm and 12.7mm with radius to diameter ratios (r/D) of 1.5 to 3. The pressure drops at two different upstream and downstream locations were investigated using empirical, experimental, and computational methods. The combination of three different air velocities, ranging from 15.24 to 45.72 m/sec, and nine different water velocities, in the range of 0.1-10.0m/s, was used in this study. CFD analysis was performed using the mixture model and a commercial code, FLUENT. The comparison of CFD predictions with experimental data and empirical model outputs showed good agreement.

/pdf/cfd-analysis-of-the-effect-of-elbow-radius-on-pressure-drop-bjcmgsu24j.pdf

CFD analysis of the effect of elbow radius on pressure drop in multiphase flow

Scarcity of fossil fuels and rapid escalation in the energy prices around the world is affecting efficiency of established modes of cargo transport within transportation industry. Extensive research is being carried out on improving efficiency of existing modes of cargo transport, as well as to develop alternative means of transporting goods. One such alternative method can be through the use of energy contained within fluid flowing in pipelines in order to transfer goods from one place to another. Although the concept of using fluid pipelines for transportation purposes has been in practice for more than a millennium now, but the detailed knowledge of the flow behaviour in such pipelines is still a subject of active research. This is due to the fact that most of the studies conducted on transporting goods in pipelines are based on experimental measurements of global flow parameters, and only a rough approximation of the local flow behaviour within these pipelines has been reported. With the emergence of sophisticated analytical tools and the use of high performance computing facilities being installed throughout the globe, it is now possible to simulate the flow conditions within these pipelines and get better understanding of the underlying flow phenomena.


The present study focuses on the use of advanced modelling tools to simulate the flow within Hydraulic Capsule Pipelines (HCPs) in order to quantify the flow behaviour within such pipelines. Hydraulic Capsule Pipeline is the term which refers to the transport of goods in hollow containers, typically of spherical or cylindrical shapes, termed as capsules, being carried along the pipeline by water. A novel modelling technique has been employed to carry out the investigations under various geometric and flow conditions within HCPs.


Both qualitative and quantitative flow diagnostics has been carried out on the flow of both spherical and cylindrical shaped capsules in a horizontal HCP for on-shore applications. A train of capsules consisting of a single to multiple capsules per unit length of the pipeline has been modelled for practical flow velocities within HCPs. It has been observed that the flow behaviour within HCP depends on a number of fluid and geometric parameters. The pressure drop in such pipelines cannot be predicted from established methods. Development of a predictive tool for such applications is one of the aims that is been achieved in this study. Furthermore, investigations have been conducted on vertical pipelines as well, which are very important for off-shore applications of HCPs. The energy requirements for vertical HCPs are significantly higher than horizontal HCPs. It has been shown that a minimum average flow velocity is required to transport a capsule in a vertical HCP, depending upon the geometric and physical properties of the capsules. The concentric propagation, along the centreline of pipe, of heavy density capsules in vertical HCPs marks a significant variation from horizontal HCPs transporting heavy density capsules.


Bends are an integral part of pipeline networks. In order to design any pipeline, it is essential to consider the effects of the bends on the overall energy requirements within the pipelines. In order to accurately design both horizontal and vertical HCPs, analysis of the flow behaviour and energy requirements, of varying geometric configurations, has been carried out. A novel modelling technique has been incorporated in order to accurately predict the velocity, trajectory and orientation of the capsules in pipe bends.


Optimisation of HCPs plays a crucial rule towards worldwide commercial acceptability of such pipelines. Based on Least-Cost Principle, an optimisation methodology has been developed for single stage HCPs for both on-shore and off-shore applications. The input to the optimisation model is the solid throughput required from the system, and the outputs are the optimal diameter of the HCPs and the pumping requirements for the capsule transporting system. The optimisation model presented in the present study is both robust and user-friendly.


A complete flow diagnostics and design, including optimisation, of Hydraulic Capsule Pipelines has been presented in this study. The advanced computational skills being incorporated in this study has made it possible to map and analyse the flow structure within HCPs. Detailed analysis on even the smallest scale flow variations in HCPs has led to a better understanding of the flow behaviour.

Computational fluid dynamics based diagnostics and optimal design of hydraulic capsule pipelines

The comparison of experimental data and results obtained from four global models – homogeneous, Dukler, Martinelli and Chisholm, used to evaluate the two-phase flow pressure drop in circular 90° horizontal elbows – is presented in this paper. An experimental investigation was carried out using three galvanized steel 90o horizontal elbows (E1, E2, E3) with internal diameters of 26.5, 41.2 and 52.5 mm, and curvature radii of 194.0, 264.0 and 326.6 mm, respectively. According to the experimental results, the model proposed by Chisholm best fitted them, presenting for each elbow an average error of E1= 18.27%, E2= 28.40% and E3= 42.10%. Based on experimental results two correlations were developed. The first one is the classical Chisholm model modified to obtain better results in a wider range of conditions; it was adjusted by a dimensionless relationship which is a function of the homogeneous volumetric fraction and the Dean number. As a result, the predictions using modified Chisholm model were improved presenting an average error of 8.66%. The second developed correlation is based on the entire two-phase mass flow taken as liquid and corrected by the homogeneous volumetric fraction ratio. The results show that this last correlation is easier and accurate than the adjusted Chisholm model, presenting an average error of 7.75%. Therefore, this correlation is recommended for two-phase pressure drop evaluation in horizontal elbows.

http://www.scielo.org.mx/pdf/imtd/v3n4/v3n4a2.pdf

Pressure Drop Models Evaluation for Two-Phase Flow in 90 Degree Horizontal Elbows

En este trabajo se presentan los resultados de la simulacion numerica por medio de la tecnica de discretizacion de los volumenes finitos de las estructuras de flujo tridimensional en un ducto rectangular con un escalon al frente. Se emplea el algoritmo SIMPLE para asociar la distribucion de presion y el campo de velocidad dentro del dominio computacional. El ducto que se propone es de forma rectangular y encierra un escalon, de tal forma que la relacion de expansion y la relacion de aspecto son iguales a dos y cuatro respectivamente. La longitud total del canal en la direccion principal del flujo es igual a 60 veces la altura del escalon, mientras que la orilla del escalon se localiza a una distancia igual a 20 veces la altura del mismo corriente abajo de la entrada del canal. A la entrada se considera que el flujo es tridimensional y completamente desarrollado. Resultados de la linea de reacomodo, linea de separacion, asi como perfiles de velocidad a diferentes planos dentro del ducto se presentan para diferentes parametros de Reynolds.

http://www.scielo.org.mx/pdf/rmf/v53n2/v53n2a2.pdf

Numerical simulation for the flow structures following a three-dimensional horizontal forward-facing step channel

A real-time virtual monitoring system of the skin factor for matrix acidizing treatments

Emission and elastic strain in InAs dot-in-a well InGaAs/GaAs structures

Gravity granular flows of cohesionless materials emerging from bottom exits and from lateral exit holes, both in vertical bins, and from face walls in tilted bins were modeled and measured. The models are based on continuum mechanics, whereas friction and gravity are the main involved forces. Measurements of the granular mass flow rates were obtained from temporal measurements of weights by using force sensors. In vertical and tilted bins the face wall thicknesses were considered in the governing correlations. Measurements are in good agreement with the theoretical predictions.

F. Sánchez Silva

Papers

Pressure Drop Models Evaluation for Two-Phase Flow in 90 Degree Horizontal Elbows

Numerical simulation for the flow structures following a three-dimensional horizontal forward-facing step channel

A real-time virtual monitoring system of the skin factor for matrix acidizing treatments

Emission and elastic strain in InAs dot-in-a well InGaAs/GaAs structures

Flows from Bins: New Results